The Journal of Raptor Research Volume 38 Number 2 June 2004 Published by The Raptor Research Foundation, Inc, THE RAPTOR RESEARCH FOUNDATION, INC. (Founded 1966 ) http://biology.boisestate.edu/raptor/ OFFICERS PRESIDENT: Brian A. Millsap SECRETARY: Judith Henckel VICE-PRESIDENT: David M. Bird TREASURER: Jim Fitzpatrick BOARD NORTH AMERICAN DIRECTOR #1: Jeff Smith NORTH AMERICAN DIRECTOR #2: Gary Santoi.o NORTH AMERICAN DIRECTOR #3: Ted Swem INTERNATIONAL DIRECTOR #1: Beatriz Arroyo INTERNATIONAL DIRECTOR #2: Ruth Tingay OF DIRECTORS INTERNATIONAL DIRECTOR #3: Steve Redpath DIRECTOR AT LARGE #1: Jemima ParryJones DIRECTOR AT LARGE #2: Eduardo Inigo-Elias DIRECTOR AT LARGE #3: Michael W. Collopy DIRECTOR AT LARGE #4: Carol McIntyre DIRECTOR AT LARGE #5: John A. Smallwood DIRECTOR AT LARGE #6: Daniel E. Varland EDITORIAL STAFF EDITOR: James C. Bednarz, Department of Biological Sciences, PO. Box 599, Arkansas State University, State University, AR 72467 U.S.A. ASSOCIATE EDITORS James R. Belthoff Juan Jose Negro Clint W. Boal Marco Restani Michael I. Goldstein Eabrizio Sergio Joan L. Morrison Ian G. Warkentin BOOK REVIEW EDITOR: Jeffrey S. Marks, Montana Cooperative Research Unit, University of Montana, Missoula, MT 59812 U.S.A. SPANISH EDITOR: Cesar Marquez Reyes, Instituto Humboldt, Colombia, AA. 094766, Bogota 8, Colombia EDITORIAL ASSISTANTS: Jennifer L. Norris, Jaimie Varner, Joan Clark The Journal of Raptor Research is distributed quarterly to all current members. Original manuscripts dealing with the biology and conservation of diurnal and nocturnal birds of prey are welcomed from throughout the world, but must be written in English. Submissions can be in the form of research articles, short communications, letters to the editor, and book reviews. Contributors should submit a typewritten original and three copies to the Editor. All submissions must be typewritten and double-spaced on one side of 216 X 278 mm (8V2 X 11 in.) or standard international, white, bond paper, with 25 mm (1 in.) mar- gins. The cover page should contain a title, the author’s full name(s) and address (es). Name and address should be centered on the cover page. If the current address is different, indicate this via a footnote. A short version of the title, not exceeding 35 characters, should be provided for a running head. An abstract of about 250 words should accompany all research articles on a separate page. Tables, one to a page, should be double-spaced throughout and be assigned consecutive Arabic numer- als. Collect all figure legends on a separate page. Each illustration should be centered on a single page and be no smaller than final size and no larger than twice final size. The name of the author (s) and figure number, assigned consecutively using Arabic numerals, should be pencilled on the back of each figure. Names for birds should follow the A.O.U. Checklist of North American Birds (7th ed., 1998) or another authoritative source for other regions. Subspecific identification should be cited only when pertinent to the material presented. Metric units should be used for all measurements. Use the 24-hour clock (e.g., 0830 H and 2030 H) and “continental” dating (e.g., 1 January 1999). Refer to a recent issue of the journal for details in format. Explicit instructions and publication policy are outlined in “Information for contributors,” J. Raptor Res., Vol. 37(4), and are available from the editor. Submit manuscripts to J. Bednarz at the address listed above. COVER: Northern Aplomado Falcon {Falco femoralis septentrionalis) . Graphite and color pencil drawing by Craig Farquhar (farquhar@grandecom.net) . Contents Aplomado Falcon Abundance and Distribution in the Northern Chihuahuan Desert of Mexico. Kendal E. Young, Bmce C. Thompson, Alberto Lafon Terrazas, Angel B. Montoya, and Raul Valdez 107 Blood-Lead and ALAD Activity Levels of Cooper’s Hawks {Accipiter cooperii) Migrating Through the Southern Rocky Mountains. Tobias j. McBride, jefFP. Smith, Howard P. Gross, and Michael J. Hooper 118 An Assessment of Cage Flight as an Exercise Method for Raptors. Dana M. Greene, Mathias Engelmann, and Todd R. Steck 125 Modeling Habitat Use and Distribution of Hen Harriers {Circus cyaneus) and Montagu’s Harrier {Circus pygargus) in a Mountainous Area in Galicia, Northwestern Spain. Luis Tapia, Jesus Dominguez, and Luis Rodriguez 133 Current Status of the Osprey in the Cape Verde Islands. Luis Palma, joao Ferreira, Rogerio Cangarato, and Pedro Vaz Pinto 141 Short Communications Development of Hunting Behavior in Hacked Aplomado Falcons, jessi l. Brown, William R. Heinrich, J. Peter Jenny, and Brian D. Mutch 148 Summer Roadside Raptor Surveys in the Western Pampas of Argentina. Michael i. Goldstein and Toby J. Hibbitts 152 Peregrine Falcons Nesting on Lake Bluffs on the Arctic Coastal Plain of Northern Alaska. Robert j. Ritchie, Ann M. Wildman, and Clayton M. White 158 Unusual Nesting of the Lesser Kestrel {Falco naumanni) in Thessaly, Greece. Christos Vlachos, Dimitris Bakaloudis, and Evangelos Chatzinikos 161 Fat Stores of Migrant Sharp-shinned and Cooper’s Hawks in New Mexico. John p DeLong and Stephen W. Hoffman 163 Spanish Ringing and Recovery Records of Booted Eagle {Hieraatus pennatus) . Ignacio S. Garcia Dios 168 Diet Shift of Barn Owls ( Tyto alba) after Natural Fires in Patagonia, Argentina. Mercedes Sahores and Ana Trejo 174 Trophic Relationships Between White-tailed Kites {Elanus leucurus) and Barn Owls ( Tyto alba) in Southern Buenos Aires Province, Argentina. Lucas M. Leveau, Carlos M. Leveau, and Ulyses FJ. Pardinas 178 Relative Abundance and Diversity of Winter Raptors in Spokane County, Eastern Washington. Howard L. Ferguson 181 Nesting of the White-throated Hawk {Buteo albigula) in Deciduous Forests of Central Chile. Eduardo F. Pavez, Christian Gonzalez, Benito A. Gonzalez, Cristian Saucedo, Sergio Alvarado, Juan P Gabella, and Alejandra Arnello 186 Letters Observation of the Chimango Caracara (Milvago chimango) Feeding on Common Lesser Toads {Bufo fernandezae) . Leandro Alcalde and Sergio D. Rosset 190 Consumption of a Ringed Kingfisher (Megaceryle torquata) by a White-tailed Hawk {Buteo albicaudatus) in Southeastern Brazil. Jose Carlos Motta-Junior and Marco Antonio Monteiro Granzinolli 191 Golden Eagle {Aquila chrysaetos) Predation Attempts on Merriam’s Turkeys {Meleagris gallpavo merriami) in the Southern Black Hills, South Dakota. Chad P Lehman and Dan J. Thompson 192 A Record of the Ornate Hawk-Eagle (Spizaetus ornatus) in Nayarit, Mexico. Carlos A. Lopez Gonzalez, Eduardo Ponce Guevara, Karla Pelz Serrano, Hugo Luna Soria, and Rodrigo Sierra Corona 193 The Raptor Research Foundation, Inc. gratefully acknowledges funds and logistical support provided by Arkansas State University to assist in the publication of the journal. THE JOURNAL OF RAPTOR RESEARCH A QUARTERLY PUBLICATION OF THE RAPTOR RESEARCH FOUNDATION, INC. VoL. 38 June 2004 No. 2 J Raptor Res. 38(2): 107-11 7 © 2004 The Raptor Research Foundation, Inc. APLOMADO FALCON ABUNDANCE AND DISTRIBUTION IN THE NORTHERN CHIHUAHUAN DESERT OE MEXICO Kendal E. Young^ and Bruce C. Thompson^ New Mexico Cooperative Fish and Wildlife Research Unit and Fishery and Wildlife Sciences Department, Box 30003, MSC 4901, New Mexico State University, Las Cruces, NM 88003 U.S.A. Alberto Lafon Terrazas Facultad de Zootecnia, Universidad Autonoma de Chihuahua, Chihuahua, Mexico Angel B. Montoya The Peregrine Fund, Boise, ID 83709 U.S.A. Raul Valdez Fishery and Wildlife Sciences Department, Box 30003, MSC 4901, New Mexico State University, Las Cruces, NM 88003 U.S.A. Abstract. — The northern Aplomado Falcon {Falco femoralis septentrionalis) historically occupied coastal prairies, savannas, and desert grasslands from southern Mexico north to southern and southwestern Texas, southern New Mexico, and southeastern Arizona. Current resident Aplomado Falcon populations are primarily in Mexico, with isolated populations in southern Texas and from northern Chihuahua to southern New Mexico. We conducted surveys in semidesert grasslands/ savannas and associated habitats in northern Chihuahua to locate Aplomado Falcons and to better delineate their distribution and abundance in the northern Chihuahuan Desert during 1998-99. Data were collected by surveying large tracts, transects in nonrandomly selected grasslands, and from a falcon monitoring study. Based on all survey effort, the minimum known population of adult Aplomado Falcons in the study area in northern Chihuahua was 79 individuals. Aplomado Falcons were primarily associated with grassland communities. Most falcon nests (88%) were found in grassland communities with soaptree yucca (Yucca data) or Torrey yucca (E torreyi). Aplomado Falcons were found fairly clustered in the north-central to north- eastern part of the study area. We found falcons nesting ca. 50 km west of the Texas border (ca. 120 km south of El Paso) in northern Chihuahua. Because Aplomado Falcons are associated with grassland communities, continued degradation of Chihuahuan Desert semidesert grasslands will continue to in- fluence their distribution. Keywords: Aplomado Falcon; Falco femoralis; Chihuahuan Desert, Chihuahua, Mexico; distribution. ABUNDANCIA Y DISTRIBUCION DEL HALCON PERDICERO EN EL DESIERTO NORTENO DE CHIHUAHUA EN MEXICO Resumen. — El Halcon perdicero del norte (Falco femoralis septentrionalis) historic amente ha ocupado praderas costeras, sabanas, y pastizales deserticos desde Mexico meridional al norte, hasta el sur y sur occidente de Texas, el sur de Nuevo Mexico y el sur oriente de Arizona. Las poblaciones residentes actuales del halcon perdicero se encuentran principalmente en Mexico, con poblaciones aisladas en el ^ E-mail address: kyoung@nmsu.edu ^ Present address: New Mexico Department of Game and Fish, P.O. Box 25112, Santa Fe, NM 87504 U.S.A. 107 108 Young et au. VoL. 38, No. 2 sur de Texas y desde el Chihuahua del norte hasta el sur de Nuevo Mexico. Conducimos estudios en pastizales/sabanas semideserticas y habitats asociados en el Chihuahua del norte para localizar Halcones perdiceros y para hacer un mejor bosquejo de su distribucion y abundancia en el Desierto Norteno de Chihuahua durante 1998-99. Los datos fueron colectados estudiando distancias largas por medio de transeptos en pastizales seleccionados (no al azar) y a partir de un estudio de monitoreo de halcones. Con base en todo el esfuerzo de estudio, la poblacion minima conocida de halcones perdiceros adultos en el area de estudio en el norte de Chihuahua fue de 79 individuos. Los halcones perdiceros estuvieron asociados principalmente con comunidades de pastizales. La mayoria de los nidos de halcon (88%) fueron encontrados en comunidades de pastizales con arboles de yucca ( Yucca data) o yucca Torrey ( Y. torreyi). Los halcones perdiceros se encontraron ligeramente concentrados en la parte norcentral a nororiental de la zona de estudio, Encontramos halcones anidando aproximadamente 50 km al occi- dente de la frontera de Texas (ca. 120 km al sur de El Paso) en el Chihuahua del norte. Debido a que los halcones perdiceros estan asociados con comunidades de pastizales, la continua degradacion de los pastizales semideserticos del Desierto de Chihuahua continuara influenciando su distribucion. [Traduccion de Cesar Marquez] The northern Aplomado Falcon (Falco femoralis septentrionalis) occupied coastal prairies, savannas, and desert grasslands historically from southern Mexico north to southern and southwestern Texas, southern New Mexico, and southeastern Arizona (Oberholser 1974, American Ornithologists’ Union 1998, Keddy-Hector 2000). In Mexico, Aplo- mado Falcons historically occurred along the east coast from Tamaulipas to Yucatan, and along the west coast in lowlands from Sinaloa and Nayarit to Oaxaca (Lawrence 1874, Cade et al. 1991, Keddy- Hector 2000; Fig, 1). The U.S. Fish and Wildlife Service (1990) and Howell and Webb (1995) sug- gested that Aplomado Falcons occurred through- out the northern Mexican Plateau. However, the lack of documented occurrences leaves the falcon’s historical distribution in the Chihuahuan Desert and elsewhere in interior northern Mexico un- clear. Aplomado Falcon reports in Durango are limited to one falcon sighted in 1950 at high ele- vation in a pine forest west of Durango City (Web- ster and Orr 1952). There were no documented reports of Aplomado Falcons in Sonora pre-1966 (Van Rossem 1945, Russell and Monson 1998). Al- den (1969) and Gallucci (1981) reported falcon sightings in Sonora in 1966 and 1979; however, Russell and Monson (1998) claimed these sightings were unsubstantiated. In Chihuahua, historical Aplomado Falcon reports were sparse. Bailey (1928) mentions a falcon was taken in 1892 at the playas of Palomas, Chihuahua, near the New Mex- ico border. Further, a nest was located in Chihua- hua, Mexico, southwest of Antelope Wells, New Mexico by Arnold Bayne in 1952 (Truett 2002). There was better documentation of early falcon reports in the United States’ (U.S.) portion of the Chihuahuan Desert (Williams 1997, Truett 2002, R. Meyer, C. Perez, and S. Williams III unpubl. data). Early reports in the northern Chihuahuan Desert indicated Aplomado Falcons were found in open plains with sparse woody vegetation (e.g., Bendire 1892, Visher 1910, Bailey 1928, Ligon 1961), Specimen records and documented sight- ings indicated that falcons were common through- out their range in the U.S. until ca. 1930 (Bent 1938, Hector 1987). Arnold Bayne located the last known historical falcon nest in southern New Mex- ico in 1952 (Ligon 1961). The last known historical falcon nest in southeastern Arizona was pre-1940s (Phillips et al. 1964, Monson and Phillips 1981). There were occasional Aplomado Falcon sight- ings in the Chihuahuan Desert in the 1960s, 1970s, and 1980s; however, these sightings were usually discounted because the species was believed to be extirpated from the Chihuahuan Desert. Williams and Hubbard (1991) considered the origin of an Aplomado Falcon photographed in southern New Mexico in 1991 a mystery, citing falcons in the sa- vannas of Veracruz as the closest known popula- tion. The resident population in northern Chihua- hua was not discovered until 1992. Current resident northern Aplomado Falcon populations are primarily in Mexico (Fig. 1). Ex- tant populations exist along the Gulf of Mexico to the Yucatan Peninsula (Howell and Webb 1995, Keddy-Hector 2000). Also, an Aplomado Falcon population exists in the northern Chihuahuan De- sert from north-central Chihuahua to southern New Mexico (Montoya et al. 1997, Truett 2002, Williams 2002, Young et al. 2002, R. Meyer, C. Perez, and S. Williams III unpubl. data). Since the 1990s, there have been occasional sightings of Aplomado Falcons in northern Chihuahua, Mexi- co near the New Mexico border, and near Lagunas June 2004 Aplomado Falcon Distribution 109 Year-round I I Occasional or Annual Sightings ( 1990 to Present) [ \ Historical Fxtent Unk. Not Reported ( I \t l ‘ ni}cctton \ - U > S 3 . /.I GRS I9S0 S^yih^rntii Figure 1. Distribution of northern Aplomado Falcons in the United States and Mexico. Map redrawn from infor- mation provided by Lawrence (1874), Webster and Orr (1952), Phillips et al. (1964), Alden (1969), Oberholster (1974), Gallucci (1981), Monson and Phillips (1981), Cade et al. (1991), Howell and Webb (1995), Montoya et al. (1997), Williams (1997), Russell and Monson (1998), Peterson and Zimmer (1998), U.S. Fish and Wildlife Service (1990), Keddy-Hector (2000), Williams (2002), Truett (2002), Meyer (unpubl. data), E, Ihigo-Elias (pers. comm.), and data collected during this study. Babicora, Mexicanos, and Bustillos, and La Perla (Benitez et al. 1999, Lafon Terrazas unpubl. data) . Further, an Aplomado Falcon was sighted in Coa- huila in the late 1990s (E. Ihigo-Elias pers. comm.). In the U.S., there are annual falcon sightings in southern New Mexico and occasional sightings in western Texas (Fig. 1) (Williams 1993, 1994, 1996, 1997, 2000, Peterson and Zimmer 1998, Truett 2002, R. Meyer, C. Perez, and S. Williams III un- publ. data). The first successful nest recorded in New Mexico since 1952 fledged three young in 2002 (Williams 2002, R. Meyer, G. Perez, and S. Williams III unpubl. data). Along the southern Texas coast, a population of Aplomado Falcons was no Young et al. VoL. 38, No. 2 initiated from reintroduction efforts (Cade et al. 1991). In addition, Aplomado Falcons were re- leased in western Texas in 2002. The Aplomado Falcon was first considered a can- didate for endangered status in 1973 (U.S. De- partment of the Interior 1973) and was listed as endangered in March 1986 (U.S. Fish and Wildlife Service 1986). At the time of listing, critical habitat was not designated because there were no known nests in the U.S. for at least 25 yr (U.S. Fish and Wildlife Service 1986). The Aplomado Falcon was added to the endangered list due to its loss as a breeding bird in the U.S. and continued threats within its range. Factors that attributed to the fal- con’s decline were primarily habitat degradation due to woody plant encroachment, and secondar- ily, egg and specimen collecting, and continued pesticide contamination (DDT) within the range of the falcon (Kiff et al. 1980, U.S. Fish and Wild- life Service 1986, Cade et al. 1991). The Mexican government listed the northern Aplomado Falcon as endangered in Mexico in May 1994 (DOF-Semarnat 1994, Ceballos and Marquez Valdelamar 2000). However, because information about population-level status of each species was lacking, governmental agencies, scientific institu- tions, and societies collaborated to review infor- mation and produce a new threatened and endan- gered species list for Mexico. This list was published in March 2002, and the status of the northern Aplomado Falcon was changed from “en- dangered” to “subject to special protection” (DOF-Semarnat 2002). Subject to special protec- tion status is given to a species or population which could become threatened from factors that nega- tively affect their viability; thus, there exists a need to promote their recovery and conservation (DOF- Semarnat 2002). Increases in reliable falcon sightings in the Chi- huahuan Desert in the early 1990s prompted ad- ditional interest in recovery of the species in New Mexico (Williams 1997, R. Meyer, C. Perez, and S. Williams III unpubl. data). We conducted raptor surveys in semidesert grasslands/ savannas and as- sociated habitats in northern Chihuahua, Mexico to locate Aplomado Falcons and to better delineate their distribution and abundance in the northern Chihuahuan Desert. We surveyed a variety of dom- inant vegetation communities to identify habitat as- sociations. We recorded presence of raptors and ravens (Corvus spp.) to investigate the association of Aplomado Falcons with presence of primary nest builders (U.S. Fish and Wildlife Service 1990). Study Area and Methods Our study area (100 735 km^) consisted of a 160-km belt south of the U.S. /Mexico border in Chihuahua, Mexico (Fig. 2). Municipalities in the study area included Ahumada, Aldama, Ascension, Buenaventura, Camargo, Casas Grandes, Chihuahua, Coyame, Delicias, Galeana, Guadalupe, Janos, Juarez, Julimes, Manuel Benavides, Nuevo Gasas Grandes, Ojinaga, Praxedis G. Guerrero, and Zaragoza. Land ownership included private and communal (ejido) land. Annual precipitation is 200-300 mm, the majority (>80%) of which occurs during July- September (COTECOCA 1978). Topography is charac- terized by disjunct north-southeast-oriented mountain ranges with maximum elevations of ca. 2200 m. Plains, lowlands, and basins are prevalent throughout the study region and are ca. 1200 m above sea level. Semidesert-basin-grassland communities consist pri- marily of alkali sacaton {Sporobolus airoides) and tobosa {Pleuraphis mutica) (COTECOCA 1978, Brown 1994, Young et al. 2002) . Lowlands predominantly contain to- bosa with honey mesquite {Prosopis glandulosa) and soap- tree yucca {Yucca data). Plains are comprised of blue grama {Bouteloua gracilis), black grama {B. eriopoda), fluff grass {Dasyochloa pulchella) , burrograss {Scleropogon brevi- folius), alkali sacaton, and sand dropseed {Sporobolus cryp- tandrus) (COTECOCA 1978, Young et al. 2002). Com- mon woody plants in plains consist of honey mesquite, creosote bush {Larrea tridentata), acacia {Acacia spp.), soaptree yucca, mariola {Parthenium incanum), and tar- bush {Flourensia cernua). Sloped areas support sideoats grama {B. curtipendula) , fluff grass, burrograss, creosote bush, lechuguilla {Agave lechuguilla) , and sotol {Dasylirion wheeleri) (COTECOCA 1978, Brown 1994, Young et al. 2002 ). Falcon Surveys. Aplomado Falcon distribution and abundance were described from surveys conducted in large sample tracts and in linear transects in northern Chihuahua during 1998-99. We also included distrihu- tion and abundance information from a separate study designed to monitor falcon habitat and productivity in northern Chihuahua (Macias Duarte 2002). Frequency of occurrence (percent of tracts in which a species occurred) analyses were restricted to raptors and ravens observed during tract surveys. We dehne a falcon nest site as a location where Aplomado Falcons nested, either successfully or unsuccessfully. We refer to a falcon detection site as a location where a nest was not found, but either a single or pair of falcons were found one or more times. Reproductive activity was not always determined for detection sites. We use the term site to refer to a spa- tially and temporally independent falcon location (in- cludes both nest and detection sites). As such, falcons located during both years of the study in the same or proximate area were only counted once. Tract surveys. Survey tracts in northern Chihuahua were selected in two ways; (1) a stratihed random sample in- dicated on the amount of dominant vegetation derived from a 1:250 000 printed vegetation map (INEGI 1982), and (2) a simple random sample of prospective areas identified during an aerial flight of the study area. For samples derived from the vegetation map, ca. amounts of dominant vegetation were estimated hy tracing poly- gon boundaries with a planimeter. A 9 X 9 km grid was placed on the vegetation map, and 60 grids (representing June 2004 Aplomado Falcon Distribution 111 Approximate Area Occupied by Af>Iomado Falcons Study Area Hucnavonliini C hihualuia Tracts • Surveyed • Not S urveyed } iudad Juiirc/ Figure 2. Distribution of tracts surveyed for Aplomado Falcons (upper right corner) and approximate areas occu- pied by Aplomado Falcons in northern Chihuahua during 1998-99. survey tracts) were randomly selected in proportion to the percent of vegetation calculated (Table 1). We also flew the entire study area in December 1998 to locate prospective survey areas that represented vegetation communities known to be used by Aplomado Falcons. Prospective areas for sampling were recorded with a Global Positioning System (GPS) receiver for subsequent falcon surveys. We randomly selected 30 of the 58 pro- spective grassland areas observed for tract placement. Af- ter a survey area was located in the field, observers estab- lished the largest tract size possible to conduct Aplomado Falcon surveys. Each tract received a complete, systematic survey by placing point stations at 0. 3-1.0 km intervals along roads, depending on vegetation and topography. Observers spent 3—5 min at each point station where they recorded all raptors and ravens detected using 8X binoculars and a 20X spotting scope. In areas vdth limited road access, observers walked and established point stations to ensure complete coverage of the tract. Between point stations on roads, observers drove <6 km/hr and recorded all individual raptors observed. Likelihood of double count- ing individual raptors was minimized by observers re- cording raptor and raven flight direction and movements during the survey. Actual surveyed area in tracts was estimated by buff- ering survey point stations 600-m (ca. maximum observ- able distance from most point stations) in ArcView 3.2 (Environmental Systems Research Institute, Inc. 2000). As such, tract size and configuration depended on jux- taposition and number of survey stations established. Transect surveys. Transect surveys were road surveys Table 1 Dominant vegetation zones derived from a 1:250 000 vegetation map and number of survey tracts randomly placed in each vegetation zone in the northern Chihuahua study area in Mexico. VoL. 38, No. 2 112 Young et al. Z H -D I— ( GO t-H CO (M or iR o R (SO R J> O OS a QO T-H 05 O L' 00 GO O O CO GO iR or H (/) GX iC o M s z X 3 o ;z; w CM I— I CD O I— I CO o o to o (M CO tn t— I CM rH no \/ T3 0 O u OJ Cl 1-1 O ctS ^ M .a a T3 — s cti ^ l/i t; ri rs Ih o u y !=! ? O N "2 2 ■? OJ ^ Sd .S 3 C 3 u CJ (U V) s ^ fi 8 1 ^ CCS 13 ^ -cC H • pH -W js R ^ 3 Rj 1/5 • pH > yj C/l ^ 3 Ul Oh ■3 •§ ” I 1> rO I ^ L g -R ^ — c O -R E o 05 flj 3 V3 .« Td 3 ^ 2 r: 2^3 be c 03 o > liH R o cti ^ o R TR u GR qj R 'O cR 'O Gh CJ -2 O CC .2 cti O R JC 13 13 N N P U D p ^ J-H 13 13 u ^ O O O <5 c/5 ^0 qj tO R 'O O 2 2 CC3 3 ^ fR s s Sh .2 *c/l OJ u R 13 c Im Ct! p O ;> U c^r oo 03 O Z 0 y 'S qj cc C J3 ai 0 O R O Gh o a cq B a o a _o 'O u _y "o u 3 13 R be fi 'C T3 b ca R flj at ^ G G> rt 42 6 tT o G o CM xC5 Cm go CM i^uci't'GO j>a5oooo 5 S 1 ( 1 ( T ^ CO iZ H o [3 Zi H Z H P 0 u 0 1 o o Q o ^ o 05 ^ 05 1 — I 1 — t GO CO GO >— I ^ ^ GO GO 00 o GO 05 O'! C^f CM lO CM O) lO CM ^ O O CM 1 — I O 05 O OM 0OX>^GM CDCMCDqo CM ' — I 1 — 1 1 — I ^ CM GO o CO lO ^ I-I CM CM O CM 0\| 05 CM f — I ^ CM CO gM CO 05 U IW y ^•e QJ \ O 1) tU -w u O -!-> U5 Oh O 15 O s-H c/5 U • ^ • i-H T3 T3 73 0 0 0 c/5 c/5 c/5 C/5 C/5 C/5 ^ U U o o o 0 cr c/5 V 15 2 H-l " *0 o- ^ o^ o ^ 5! 1) O >-3-0 0 O O cS .Eh -O c/5 0 02 0 .O "3 ^ HH ■> -2 Cl T3 xl IJ 0 « h O 4_J (J « b TO « 15 0 Ti K O D rS O Q u =! «5 V U % u n3 Oi CTJ I 00 O) G . oo "0 1) I-H ^ - > c G ¥ ^ f- s ^ r1 m w o ^ rJ C fa 1 O. o ^ 'I“< xrx G OJ M £ G M HH the flight of the study area) due to restricted land access or time constraints (Fig. 2). During May-October 1998, four field crews spent 308 hr surveying 47 tracts. Tract area aver- aged 26.4 ± 1.1 km^, but ranged from 7.0-41.8 km^. In 1998, we surveyed 1242 km^ in the tracts and a total of ca. 1300 km^ including transect sur- veys. During February-October 1999, five field crews surveyed 31 tracts representing 438 hr of survey time. Tract area averaged 38.1 ± 2.9 km^, but ranged from 16.4—77.7 km^. In 1999, we surveyed 1182 km^ in the tracts and a total of ca. 1467 km^ including transect surveys. Larger tracts were not feasible to establish and survey because of vegeta- tion heterogeneity, restricted land access, and time constraints. Tracts surveyed in 1998 were primarily shrub- dominated communities (84%), comprised of cre- osote bush-tarbush, mesquite-acacia, or creosote- tarbush/mesquite-acacia. Conversely, in 1999, tracts surveyed were primarily in grassland com- munities (75%), represented by grasslands with or without complexes of mesquite-acacia, creosote bush-tarbush, or yucca (Table 2). Aplomado Falcon Abundance and Distribution. Aplomado Falcons were detected in 17 (25%) of the 68 tracts surveyed. Tract surveys yielded four nests and 14 detection sites, representing 11 falcon pairs and seven singles, for a total of 29 birds. No additional falcons were found in tracts surveyed in both years. An additional three pairs (one nest and two detection sites) were located during transect surveys. The monitoring study located 13 falcon nests and nine detection sites representing 22 pairs. Based on combined survey effort, the mini- mum known population of adult Aplomado Fal- cons identified in the study area during the survey period was 79 individuals (43 independent sites; 18 nest and 25 detection sites). However, given that detection rates for Aplomado Falcons was low (e.g., >40 survey hr per site was needed for each detec- tion), additional falcons probably would be located with additional surveys. Aplomado Falcons were associated with most vegetation types, but they were detected most often in grass-dominated communities (Table 3). Specif- ically, 16 (88%) Aplomado Falcon nests and 10 (40%) detection sites were found in grassland com- munities with soaptree yucca or Torrey yucca (T torreyi). Of the 79 individuals found in northern Chihuahua, only three single birds were located in 114 Young et al. VoL. 38, No. 2 o u ■>< V CS 0 j:: Cd 3 IB u c !h OJ X ■M o S3 5 3 o d Q a ;z H 2; w Q Z w w p Z V) w H J> CM 00 01 lO CM O) J> «3 in m CM GM on e o u P o (U bjo OJ > 4-1 G P O t3 43 u c^ V 0 d 2 c/2 P P O z c55 C/5 pcS a C^I CM GO Cn CO ^ G^( «3 CO "O 43 ■N 4-1 P 0/ 03 ri P T3 ,P T3 P P cn P c/2 W H c55 p o d ;z z o 1 -^ H O w h p Q c /2 H c /2 W CO o in ofi CM in (M 43 00 P O u 13 ij-i o ~a p 6 ’&4 u V rO £ p p GO P 02 02 I 00 -4 ^P 02 f— I ^ Z D S O U Z 0 p CP z I— I s o Q P 43 u ^ \ p p (U 4J S3 O ■P Ph o p p O s-4 CT) U "O "O "O p p p C /5 iZJ i /5 c/3 C/3 C/5 ^ ^ ^ o o o p cr V3 1) p s •p o^ P c« p []j o P 33 5^ 2 33 P ’o ^ P P o 43 \ P • ^ P P P Tj P H P P 43 43 43 43 C/) p p p p •s -s ^ S P « C rr 5-1 P « ‘3 in 'P S i.4 P P O P 43 ■rt Cfi Sh == cr .n t« I- p p -B 02 CO P ^ O ^ 43 0) ^ 8 p p p p 43 43 -W • ^ ■ 1 -^ 5 3: t3 t3 P P _P _P 3 3 p P p p 43 43 V2 [O 4 M a; o; ^ c/3 C/} OJ QJ O P P H shrub-dominated communities. No falcon detec- tions occurred in creosote bush/tarbush commu- nities (Table 3). Aplomado Falcons were fairly concentrated in the north-central to northeastern part of the study area (Fig. 2). This distribution coincides closely with the distribution of extensive grasslands in northern Chihuahua identihed from our aerial flight. We found falcons nesting ca. 50 km west of the Texas border (ca. 120 km south of El Paso, TX) in northern Chihuahua. Also, single Aplomado Falcons were detected in the same area ca. 12-18 km south of the New Mexico border near Palomas, Chihuahua, in each survey yr. Reproductive status for these detections was not determined. Aplomado Falcons rely on nests constructed by other raptors or corvids. Potential nest builders present in northern Chihuahua included ravens (primarily Corvus cryptoleucus) , Swainson’s Hawk {Buteo swainsoni), Red-tailed Hawk {Buteo jamaicen- sis), Harris’s Hawk {Parabuteo unicinctus), and White-tailed Kite {Elanus leucurus). Except Harris’s Hawk and White-tailed Kite, these nest builders were common in tracts where Aplomado Ealcons were detected (>70% frequency; Table 4). Swain- son’s Hawks, Red-tailed Hawks, and ravens were more commonly detected in tracts with Aplomado Falcons than in tracts without Aplomado Falcons (X^ = 34.56, df = 3, P < 0.001). Discussion and Conservation Implications Aplomado Falcons are fairly conspicuous when foraging or perching on tall substrates. However, locating new falcons required >40 survey hr per site (estimated from tract surveys), and determin- ing nesting status required additional time. As such, methods that require complete surveys of large areas are more likely to detect falcons. We detected falcons in 25% of tracts surveyed, locating 18 falcon sites which were not previously known. Given the short duration of surveys, we feel the tract survey method provided reasonable results. Before the 1980s, information on Aplomado Fal- cons in the Chihuahuan Desert was limited to a few incidental and historical accounts. The state of knowledge has developed from the perception that Aplomado Falcons were extirpated from the Chi- huahuan Desert, to documenting a population that exists from north-central Chihuahua to southern New Mexico. However, it seems that the falcon population on the Mexican Plateau is geographi- cally isolated from coastal populations (Fig. 1). Ad- ditional research is necessary to better define pop- June 2004 Aplomado Falcon Distribution 115 Table 4. Association of raptor species observed in 17 survey tracts with Aplomado Falcon detections and 51 tracts without Aplomado Falcon detections in northern Chihuahua, Mexico in 1998-99. Number of Tracts With Aplomado Falcons'* Without Aplomado Falcons Number Percent Number Percent Swainson’s Hawk 17 100 33 65 Ravens 16 94 49 96 Red-tailed Hawk 12 71 25 49 White-tailed Kite 2 12 1 2 Harris’s Hawk 1 6 1 2 '* Detection of Aplomado Falcons was highly associated with tracts where hawks and ravens were detected (x^ = 34.56, df = 3, P = <0.001); White-tailed Kite and Harris’s Hawk detections were combined for analyses. ulation dynamics and connectivity between falcon populations in Mexico. The U.S. Fish and Wildlife Service (1990) stated that critical information regarding falcon distribu- tion, abundance, and habitat requirements in Mex- ico was needed to aid in recovery of the species. Our study, as well as studies by Montoya et al. (1997), Truett (2002), and R. Meyer, C. Perez, and S. Williams III (unpubl. data), will aid resource managers in developing recovery strategies for the falcon in the Chihuahuan Desert by providing baseline information on the current distribution of the falcon. The Chihuahuan Desert is the largest desert (ca. 629 000 km^) in North America (Beck and Gibbens 1999, Dinerstein et al. 2001) and is among the most biologically diverse desert ecoregions world- wide (Ricklefs and Schluter 1993). Most of the Chi- huahuan Desert is located in the states of Chihua- hua and Coahuila in Mexico, but portions extend into eastern Arizona, southern New Mexico, and western Texas. This vast and unique arid region supports a wide variety of habitats including grass- lands, scrublands, shrub communities, and yucca woodlands as well as mixed conifer forests and oak woodlands at higher elevations (Gehlbach 1993). About 14% of Mexico’s land area is covered by grasslands of which 90% occur in arid and semi- arid regions (Burquez et al. 1998). Although lim- ited in area, grasslands are vital to certain species and to the biodiversity of the Chihuahuan Desert (Beck and Gibbens 1999). The Mexican government created the National Commission for the Knowledge and Use of Biodi- versity (CONABIO) in 1992 that established a net- work of regional areas that were important for bio- diversity conservation. In the Chihuahuan Desert portion of the Aplomado Falcon’s range, four pri- ority areas for biodiversity conservation in grass- land habitats were identified (Arizmendi and Mar- quez 1999). CONABIO also established areas that were considered important for the conservation of birds (AICAS) in Mexico. However, within the range of the Aplomado Falcon in the Chihuahuan Desert, there was only one area designated near Janos, Chihuahua. Although there are occasional falcon sightings in this AICAS, there were no AI- CAS designated in areas of known year-round Aplomado Falcon habitation. Given the falcon’s status of “subject to special protection” in Mexico, updated information on Aplomado Falcon distri- bution may assist in evaluating areas for future AI- CAS in Chihuahua, Mexico and promote falcon re- covery and conservation. The U.S. Fish and Wildlife Service (1986) impli- cates habitat degradation due to brush encroach- ment as the main factor responsible for disappear- ance of Aplomado Falcons from the U.S. The Chihuahuan Desert has undergone considerable transition in vegetation communities since the mid-1800s, primarily from perennial grassland to shrubland (Buffington and Herbel 1965, Allred 1996, Beck and Gibbens 1999). Over the past cen- tury, factors such as climatic changes, diversion of surface water for agricultural purposes, livestock grazing, erosion, introduction of exotic plant and animal species, and increased urban development have profoundly and negatively impacted the nat- ural processes of the Chihuahuan Desert (Lloyd et al. 1998, Beck and Gibbens 1999). Changes in bird assemblages, including raptors, associated with al- tered vegetation structure and climatic conditions 116 Young et ai.. VoL. 38, No. 2 have been detected and discussed by Raitt and Pimm (1976, 1977) and Lloyd et al. (1998) for Chi- huahuan Desert environments. Change in grass- lands will naturally affect species that are grassland adapted. The current state of knowledge on Aplo- mado Falcons indicates that this falcon is likely to be detrimentally affected by alteration and loss of grassland habitat. Further, key raptor or raven spe- cies relied upon by Aplomado Falcons to provide nest structures have substantial association with grassland dominated communities (Desmond et al. in press). Grassland conservation is paramount in conserving Aplomado Falcons and other grassland birds in the Chihuahuan Desert. Acknowledgments Research was funded by the Bureau of Land Manage- ment, White Sands Missile Range, Fort Bliss Military Res- ervation, U.S. Fish and Wildlife Service, Seville ta Nation- al Wildlife Refuge, The Peregrine Fund, Border Wildlife Consultants, T & E, Inc., La Tierra Consulting, World Wildlife Fund, and Geo-Marine Inc. Additional financial support was provided by the New Mexico Agricultural Ex- periment Station. We greatly appreciate the Secretaria de Medio Ambiente Recursos Naturales y Pesca for provid- ing the necessary permits to conduct research in Mexico. We thank A. Alvarez, E. Carreon, E. Carrillo, C. Mendez, R Meyer, J. Montoya, C. Morales, F. Pinion, R. Rodriguez, C. Sanchez, and E. Zamarron for their assistance in col- lecting data. S. Lanham, Environmental Flying Services, Tucson Arizona, provided a productive flight over north- ern Chihuahua. We thank M. Howard, B. Locke, R. Mey- er, C. Perez, and S. Williams for helpful critiques of this manuscript. We thank the numerous private landowners in Chihuahua, Mexico with a special thanks to A. Borun- da and E. Baeza for providing land access. Literature Cited Alden, P. 1969. Finding the birds in Western Mexico; a guide to the States of Sonora, Sinaloa, and Nayarit. Univ. Arizona Press, Tucson, AZ U.S.A. Allred, K.W. 1996. Vegetative changes in New Mexico rangelands. N.M. J. Sci. 36:169-231. American Ornithologists’ Union. 1998. Checklist of North American birds, 7th Ed. American Ornitholo- gists’ Union, Washington, DC U.S.A. Arizmendi, M.C. and V.L. Marquez. 1999. Areas de im- portancia para la conservacion de las aves de Mexico. 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New Mexico Cooperative Fish and Wildlife Research Unit, Las Cruces, NM U.S.A. Received 26 March 2003; accepted 12 November 2003 / Raptor Res. 38 (2) :1 18-124 © 2004 The Raptor Research Foundation, Inc. BLOOD-LEAD AND ALAD ACTIVITY LEVELS OE COOPER’S HAWKS (ACCIPITER COOPERII) MIGRATING THROUGH THE SOUTHERN ROCKY MOUNTAINS Tobias J. McBride^ The Institute of Environmental and Human Health, Environmental Toxicology Department, Texas Tech University, Eubbock, TX 79409 US.A. Jeff R Smith and Howard P. Gross^ HawkWatch International, 1800 South West Temple, Salt Lake City, UT 84115 U.S.A. Michael J. Hooper The Institute of Environmental and Human Health, Environmental Toxicology Department, Texas Tech University, Lubbock, TX 79409 U.S.A. Abstract. — Predatory or scavenging raptors can be exposed to lead contamination through the inges- tion of hunter-injured or killed game species that contain residual lead bullets, pellets, or fragments thereof, or prey contaminated by lead from other anthropogenic sources. We studied the incidence of lead exposure in Cooper’s Hawks {Accipiter cooperii) by sampling southward and northward migrating populations. Cooper’s Hawks have been regularly captured for biological data collection at two long- term monitoring and banding stations in north-central New Mexico. We identified blood-lead concen- trations, erythrocyte ALAD activity, and hematocrit levels in fall migrating adults and Juveniles (N = 45 and 15, respectively), and spring migrating adults (N = 38; no juveniles were captured in spring). Blood- lead concentrations of spring migrating adults (x = 0.063 ± SE 0.011 |xg/g) were significantly greater than both fall adults and juveniles (0.032 ± 0.003 (xg/g and 0.028 ± 0.004 (xg/g, respectively). Blood- lead concentrations did not reach levels sufficient to inhibit erythrocyte ALAD activity or depress he- matocrit levels. ALAD activity appeared to be age-dependent, however, as activity in fall juveniles (74.9 ± 2.2 units) was significantly greater than in both fall and spring adults (63.0 ± 2.9 units and 54.0 ± 3.1 units, respectively). Hematocrit values indicated no detectable differences between migration season or age. Our findings suggested that Cooper’s Hawks were exposed to higher environmental levels of lead in their winter range than they were in the breeding range, though not at concentrations known to cause detrimental health effects. Key Words: Cooper’s Hawk, Accipiter cooperii; lead', ALAD', migration; toxicology. PLOMO SANGUINED Y NIVELES DE ACTIVIDAD ALAD EN HALCONES DE COOPER MIGRATO- RIOS {ACCIPITER COOPERII) EN EL SUR DE LAS MONTANAS ROCOSAS Resumen.— Las rapaces de predadoras o carroneras pueden estar expuestas a contaminacion con Plomo a traves de la ingestion de especies de caza, heridas o matadas, que contienen plomo residual de balas, perdigones, fragmentos de los misraos, o presas contaminadas con plomo a partir de otras fuentes antropogenicas. Estudiamos la potencialidad a la exposicion al plomo en los gavilanes de Cooper {Ac- cipiter cooperii) tomando rauestras de sus poblaciones migratorias hacia el sur y hacia el norte. Los Halcones de Cooper han sido capturados regularmente para colectar datos biologicos en dos estaciones de monitoreo y marcaje a largo plazo en el Norte-centro de Nuevo Mexico. Las concentraciones de plomo sanguineo, la actividad ALAD de los eritrocitos, y los niveles de hematocrito fueron identificados en adultos y juveniles emigrantes de otono {N = 45 y 15, respectivamente), y adultos migrantes de primavera {N = 38; ningun juvenil fue capturado en la sesion de primavera). Las concentraciones de plomo en la sangre de los adultos migratorios de primavera {x = 0.063 ± ES 0.011 |xg/g) fue incre- * E-mail address: toby.mcbride@tiehh.ttu.edu ^ Present address: National Parks Conservation Association, P.O. Box 1836, Yucca Valley, CA 92286 U.S.A. 118 June 2004 Blood-lead in Migrating Cooper’s Hawks 119 menlando significativamente en comparacion tanto con los adultos como con los juveniles de otono (0.032 ± 0.003 pg/g y 0.028 ± 0.004 pg/g, respectivamente) . Las concentraciones de plomo en la sangre no alcanzaron niveles suficientes para que inhibieran reconociblemente la actividad ALAD de los eritrocitos o deprimieran los niveles de hematocrito. Sin embargo, la actividad ALAD parecio de- pender de la edad, como actividad en los juveniles de otono (74.9 ± 2.2 unidades) fue significativamente mas alta que para los adultos de otono y primavera (63,0 ± 2.9 unidades y 54.0 ± 3.1 unidades, respectivamente) . Los valores de hematocritos indicaron diferencias no detectables entre la estacion de migracion o la edad. Los resultados sugieren que los gavilanes de Cooper estan expuestos a niveles ambientales mas altos de plomo en su rango sur que en el del norte, aunque no en concentraciones conocidas que causen efectos lesivos a la salud. [Traduccion de Cesar Marquez] The toxicological risks to waterfowl from spent lead shot used in hunting are well documented (Bellrose 1959, Stout and Cornwell 1976, Zwank et al. 1985, Sanderson and Bellrose 1986), and have led to the elimination of lead-based ammunition used for waterfowl hunting in United States and Canada. Investigations have also assessed the dan- gers of lead-based ammunition in upland game and mammal hunting. A risk assessment of lead effects in upland-bird species concluded that lead is likely to accumulate in birds following accidental ingestion of lead shot (Kendall et al. 1996). Lead artifacts and sinkers have been ingested as grit in high hunting-use and high fishing-use areas (Bur- ger et al. 1997, Lewis et al. 2001), resulting in pro- longed release of lead within the gizzard. Game birds may also be injured or killed during hunting attempts, but remain uncollected in the field. Sub- sequently, scavengers and raptors may be exposed to lead contamination through ingestion of these incapacitated birds. Investigations of expelled castings collected from two wild raptor populations in Spain found lead shot artifacts in 6% and 11% of those collect- ed (Mateo et al. 2001). Prevalence as high as 70% was reported in Bald Eagle {Haliaeetus leucocephal- us) castings in Utah (Platt 1976). Both of these cas- es indicate exposure from an array of food items. Lead toxicosis and exposure to lead shot have been recognized in a variety of wild raptors includ- ing eagles, goshawks, vultures, and kites (Garner 1991, Miller et al. 1998, Platt et al. 1999, Wayland et al. 1999, Mateo et al. 2001). Documented lead- artifact-induced mortalities of Golden Eagles {Aq- uila chrysaetos). Red-tailed (Buteo jamaicensis) and Rough-legged hawks (Buteo lagopus) , and Peregrine (Falco peregrinus) and Prairie falcons (Falco mexican- us) , species not known to rely heavily on waterfowl for prey items, further imply a secondary risk of lead toxicosis from upland-bird and mammal prey (Locke and Friend 1992). Lead poisoning result- ing from the ingestion of lead fragments in con- sumed carcasses likely contributed to the historic decline of the California Condor (Gymnogyps cah- fornianus; Pattee et al. 1990, Meretsky et al. 2000). More recently, lead contamination has impacted the condor reintroduction program with the deaths of at least four birds in northern Arizona (Cilek et al. 2000) caused ostensibly by lead-artifact ingestion. Lead toxicity induces effects on vascular, ner- vous, renal, immune, reproductive, and hemato- poietic systems, as well as behavioral abnormalities (Eisler 1988, Burger 1995). At lower tissue concen- trations, several biomarkers have been used to as- sess sublethal effects. Delta-aminolevulinic-acid de- hydratase (ALAD) is a widely studied, heme-related enzyme that is altered by lead contamination at low exposure levels. This zinc-dependent enzyme is easily inhibited by lead substitution and has been extensively characterized as a sensitive indicator of low-level lead exposure (Hoffman et al. 1981, Goe- ring et al. 1986, Scheuhammer 1987, Pain 1996, McBride 2002). With increased exposure and ALAD inhibition, detrimental health effects may occur with decreases in hemoglobin production and erythrocyte concentrations. Blood-sample col- lection and analysis, thus, provides a sensitive, non- lethal means for monitoring health effects and lead-body burden. Cooper’s Hawks (Accipiter cooperii) are a medium- sized raptor, breeding throughout much of the United States, southern Canada, and northern Mexico. Inhabiting primarily coniferous and mixed forests (Rosenfield and Bielefeldt 1993), they can become habituated to human disturbance and may use urban and suburban areas that pro- vide appropriate habitat (Stahlecker and Beach 1979, Boal and Mannan 1999). Cooper’s Hawks routinely feed on avian prey as a primary food 120 McBride et al. VoL. 38, No. 2 source, with small game birds such as dove (e.g., Zenaida spp.) and quail (e.g., Colinus virginianus) being potential prey (Rosenfield and Bielefeldt 1993, Boal 1997). This places the hawks at risk of ingesting spent-lead shot imbedded in injured game birds. Consequently, the Cooper’s Hawk is a species of primary concern for lead exposure due to its predation on upland game birds (Kendall et al. 1996). Migratory Cooper’s Hawks are regularly cap- tured for biological data collection each yr at two long-term monitoring and banding stations in north-central New Mexico (Hoffman et al. 2002). We investigated lead exposure and related health effects in the breeding and wintering ranges of mi- gratory Cooper’s Hawks by sampling their south- ward and northward migrating populations, re- spectively, at these sites. Study Area and Methods Cooper’s Hawks were trapped during migration at two relatively close research sites in the Cibola National For- est of north-central New Mexico. Blood sampling oc- curred during normal processing of captured birds for banding and data collection. Samples were collected at the Manzano Mountains station (34°42.25'N, 106° 24.67'W) during fall migration from 15 September-21 October 2001 and at the Sandia Mountains station (35°05.21'N, 106°25.93'W) during spring migration from 11-14 April 2002. These two sites are located ca. 40 km apart along the same migratory-flight path, and have been situated to better sample migrants during each re- spective season. Samples were taken from all birds cap- tured, regardless of gender or age class. Migrating birds were trapped using captive lure birds and an assortment of bow-nets, dho-gaza traps, and mist nets (Hoffman et al. 2002) - Blood samples were collected nonlethally via brachial veni-puncture, and separated into aliquots of ca. 150 pi for ALAD activity determina- tions, with the remaining sample stored in chemically clean vials for metal analysis. Samples were packed in ice and returned to lab facilities where they were stored at — 80°C until analysis. Packed cell volumes (PCVs) of the samples were determined at the time of collection using 100 pi microhematocrit capillary tubes. Sample preparation for lead analysis used a modifica- tion of U.S. Environmental Protection Agency (1996) method No. 3050B. Blood samples were placed in Teflon beakers and digested with 5 ml nitric acid on 120°C hot plates. Upon complete digestion, the nitric acid was evap- orated to ca. 1-2 ml. Aliquots of 1.5 ml hydrogen per- oxide (30%) were added and the samples were heated until fully reacted. Samples were transferred to 10 ml volumetric flasks and brought up to final volume using ultra-pure (MilliQ®, Millipore, Billerica, MA U.S.A.) wa- ter All samples were analyzed for lead utilizing a Perkin Elmer® (Perkin Elmer, Wellesley, MA U.S.A.) AAnalyst 600 atomic absorption spectrophotometer with graphite furnace (GFAA) and all data captured by Perkin Elmer® AAWinLab (version 3.71) instrument control software. Five-point calibration curves were developed using trace- able NIST standards. The method-detection limit for lead in blood samples, on a wet-weight basis, was 0.034 |xg Pb/ g blood. Samples falling below the detection limit (BDL) were assigned a value of one-half the detection limit (0.017 pg/g). Erythrocyte ALAD enzyme activity was measured using a modification of Pain (1987). Three 25 pi aliquots of previously frozen whole blood were each added to 725 pi ultra-pure water prior to incubation. The assay was started by the addition of 500 pi of 8-aminolevulinic acid (ALA; 100 mM final concentration, or FC) in sodium phosphate buffer (pH 6.4), and incubated in the 38°C water bath for 1 hr. Enzyme activity was halted with the addition of 500 pi of trichloroacetic acid solution (612 mM FC) . Precipitated proteins were separated by centri- fugation (2000 rpm for 10 min) and 100 pi aliquots of the supernatant solution containing the reaction prod- uct, porphobilinogen, were pipetted into the appropriate wells of a 96-well microtiter plate. Ehrlich’s indicator re- agent (100 pi) was then added to each well, which was then covered and analyzed immediately. Absorbance was read every min for 10 min, at 555 nm (kinetic mode) using a SPECTROMax Plus 96-well spectrophotometric plate reader controlled by Molecular Devices® SOETmax Pro software (Molecular Devices Corp., Sunnyvale, CA U.S.A.) . The maximum value (background corrected) was selected for use in the activity determination. Enzyme activity was calculated using the equation: Activity = (11580 X Max. Absorbancc 555 ) /Hematocrit where 1 1 580 is a conversion factor based on the molar- extinction coefficient specific to the porphobilinogen/jP dimethylaminobenzaldehyde complex (62 000 M^^ cm“^), as well as stoichiometric calculations and dilution factors. Max. Absorbancc 555 was mea.sured in absorbance units and Hematocrit was expressed as a percent. ALAD activity units were expressed as nmoles ALA X min“’^ X ml RBC k Statistical analyses were performed using SigmaStat for Windows (Jandel Corporation, SPSS Inc., Chicago, IL U.S.A.). Hematocrit values and ALAD activity were ana- lyzed for significant differences between ages and be- tween migration seasons using a one-way analysis of var- iance (ANOVA). Blood-lead concentrations were not normally distributed due to numerous samples assigned the BDL value of one-half the detection limit. Therefore, data sets were tested using a Kruskal-Wallis analysis of ranks test. No sex-dependent differences were identified for any of the tested parameters (P> 0.28); thus, genders were combined for the final statistical analyses. Linear regression equations were calculated to examine the re- lationships between detectable blood-lead concentrations and ALAD activity. Eor all tests, results were considered significant if P ^ 0.05. Results We collected 98 blood samples over the two mi- gratory seasons. We collected 60 samples during fall migration: 15 from juveniles, 45 from adults June 2004 Blood-lead in Migrating Cooper’s Hawks 121 (Fig. lA) . We collected 38 samples from adults dur- ing spring migration. We were unable to capture any juveniles during the spring collection period. Fall juvenile lead concentrations varied from 0.017 (half detection limit) to 0.071 p-g/g {x = 0.028 ± SE 0.004 pg/g, median = 0.017 pg/g). Only six of 15 samples were above detectable limits (x = 0.045 ± 0.005 pg/g). Fall adult lead concentrations var- ied from 0.017 to 0.112 pg/g {x - 0.032 ± 0.003 pg/g, median = 0.017 pg/g). Nineteen of 45 val- ues were above detectable limits (x = 0.052 ± 0.004 pg/g). Spring adult values (N — 38) varied from 0.017 (half detection limit) to 0.356 pg/g (x = 0.063 ± 0.011 pg/g, median ^ 0.047 pg/g). Twenty-five of 38 values were above detectable lim- its (x — 0.086 ± 0.015 pg/g). Blood-lead levels showed significant variation between migration season and age (F = 0.005), with higher concen- trations in spring adults than either fall adults or fall juveniles. Due to storage and volume constraints, only 47 of 98 (46%) blood samples were analyzed for erythrocyte AIAD enzyme activity (Fig. IB). Fa ll juvenile samples (N = 9) showed activities ranging from 67.2-84.2 units (x = 74.9 ± 2.2 units). Fall adult samples (N = 20) showed activities ranging from 43.8-100 units (x = 63.0 ± 2.9 units). Spring adult samples varied from 16.4-67.1 units (x = 54.0 ±3.1 units). Enzyme activity appeared to be age- dependent; fall juvenile values were significantly higher than fall adult and spring adult values (P = 0.001). Eurther, spring adult ALAD enzyme activity was reduced 28% and 14% when compared to fall juvenile and fall adult samples, respectively. We assessed packed cell volumes for 58 of 98 (59%) blood samples (Eig. 1C). Eall juvenile values (N = 10) varied from 42-48% (x = 45.9% ± 0.6). Eall adult hematocrit values (N — 20) varied from 41—50% (x = 46.4% ± 0.5). Values for spring adult samples (N= 28) ranged from 37-56% (x = 47.6% ± 1.0). Packed cell volumes did not vary signifi- cantly between seasons or ages. In examining the relationship between blood- lead concentration and health effects, individual- ALAD activity was regressed as a function of cor- responding blood-lead concentration. However, only 2% of the variability in enzyme activity could be explained by the concentration of lead in the blood (F = 0.02). Discussion Blood-lead levels in Ealconiformes are consid- ered “subclinical” at levels between 0.2 and 1.5 A 1 'Si 'Sk 3 a e ■« A A B IV=45 \= 3 » • SubcHnlcai g U I e s 0.1 : A 1 0.01 Figure 1. A. Blood-lead concentration (pg/g) of juve- nile and adult Cooper’s Hawks during fall and spring migration. Mean (dashed line), median (solid line), 25th and 75th percentiles (box limits), standard deviation (er- ror bars), and outliers (individuals points) of blood-lead concentrations. Subclinical effects level (Franson 1996) indicated for reference. Groups with the same letter in common are not significantly different (P ^ 0.05). B. ALAD enzyme activity in juvenile and adult Cooper’s Hawks during migration. C. Hematocrit values of juvenile and adult Cooper’s Hawks during migration. 122 McBride et al. VoL. 38, No. 2 |JLg/g (Franson 1996). These levels are elevated above background concentrations (defined as <0.2 iJLg/g) and are indicative of initiating physi- ological effects (Franson 1996). In all, three of 98 (3%) blood samples analyzed equaled or exceeded this background level, with all such samples col- lected during spring migration. Though the ma- jority of Cooper’s Hawks tested demonstrated little evidence of significant lead intoxication, these three individuals exhibited sufficiently increased blood-lead concentrations that suggested exposure to either contaminated food items or ingestion of lead artifacts. Mallards {Anas platyrhynchos) dosed with a single No. 4 shot exhibited similar blood- lead levels of 0.317 |xg/g 1 mo post-dose, and 0.207 |xg/g 3 mo post-dose (Dieter and Finley 1978), demonstrating the potential for blood concentra- tions to stay elevated for extended periods from a single lead-artifact exposure. In acute exposure, in- gested lead quickly equilibrates between blood and soft tissues, remaining elevated in both for several weeks to months following exposure (Pain 1996). Blood-lead concentrations may take up to 4 mo to return to normal levels (Dieter and Finley 1978), thus the potential exists that the three notable Cooper’s Hawks had much higher blood-lead lev- els prior to leaving for their northward migration. Increased blood-lead levels during spring migra- tion indicated that Cooper’s Hawks migrating along the central Rocky Mountain Flyway were be- ing exposed to higher environmental lead levels while in their winter ranges (specifically southern New Mexico, southwest Texas, and northwest Mex- ico; Hoffman et al. 2002). Hunting seasons for most avian and mammal game species occur dur- ing late fall and winter in the United States and Mexico. Thus, risk of exposure for these raptors to spent-lead shot likely increases in their wintering range and may explain higher blood-lead levels in spring migrant hawks. Interestingly, an analysis of Cooper’s Hawk banding data from several western migration sites showed that more than half of the banded hawks recovered during winter had been shot, with the majority recovered in Mexico (Hoff- man et al. 2002). This suggests that wintering Coo- per’s Hawks occupy an environment where the risk of direct hunting injury as well as secondary lead contamination may be higher than during their breeding season. Due to the historic use of lead in gasoline and its presence in industrial waste, lead is ubiquitous throughout the environment, resulting in back- ground levels that may be detected in almost all animal tissues (Eisler 1988). Cooper’s Hawks may inhabit urban centers that provide habitat (Boal and Mannan 1999), and may be exposed to in- creased environmental lead as a result of localized anthropogenic sources. Increased exposure to lead in urban areas has been noted in several avian spe- cies, including Rock Pigeon {Columba livia), Euro- pean Starlings (Sturnus vulgaris), House Sparrows {Passer domesticus) , and American Robins {Tardus migratorius; Getz et al. 1977, Kendall and Scanlon 1982, Grue et al. 1986), all potential prey species of Cooper’s Hawks (Rosenfield and Bielefeldt 1993). Increased tissue-lead concentrations also have been noted in other urban-dwelling avian predators, including Peregrine Falcons (DeMentet al. 1986). Even without the risks associated with eating hunter-injured prey items. Cooper’s Hawks inhabiting urban centers would likely be exposed to lead-contaminated food items. The inhibition of erythrocyte ALAD activity is a well-established biochemical alteration associated with lead exposure in birds (Hoffman et al. 1985, Beyer et al. 1985, Henny et al. 1991). Nestling American Kestrels {F. sparverius) exhibited ALAD inhibition at 0.12 (xg/g (McBride 2002), and showed 55% ALAD activity inhibition with mean blood-lead levels of 0.25|xg/g (Henny et al. 1994). The 14-28% reduction in ALAD activity seen be- tween fall and spring migrants is feasibly influ- enced by lead-induced-enzyme depression. With greater sampling, we would expect to see a dose- dependent decrease in enzyme activity occurring at lead levels greater than the background thresh- old of 0.2 |xg/g established by Franson (1996) . The generally low blood-lead levels likely obscured an identifiable dose-response inhibition of ALAD ac- tivity, as the lowest ALAD activities detected did not correlate to the three notable high blood-lead in- dividuals. Levels of enzyme inhibition seen were not indic- ative of levels sufficient to significantly inhibit erythrocyte production (Fig. 1C). Franson et al. (1983) noted no significant change in hematocrit of American Kestrels dosed with 50 ppm of lead in the diet for 5 mo, despite a 20% ALAD inhibition. Hematocrits of breeding Cooper’s Hawks in Ari- zona (male: x = 53.7%; female: x = 50.7%; Boal et al. 1998) were higher than fall-migrating Coo- per’s Hawks captured in Utah (x = 49.2% ± 2.6; Gessaman et al. 1986), suggesting a potential sea- sonally or reproductively-induced fluctuation; how- June 2004 Blood-lead in Migrating Cooper’s Hawks 123 ever, no seasonal differences were identified in this study. This study is the first effort in an investigation of secondary exposure to lead-based ammunition and lead-based fishing sinkers in raptors, and will be followed by further assessments of other migra- tory and nonmigratory raptors from other major U.S. migratory flyways. In a similar investigation of migrating Sharp-shinned Hawks {Accipiter striatus) in the eastern United States (Pennsylvania and New Jersey), liver-lead concentrations from 19 in- dividuals {x = 0.007 pg/g wet weight) were found to be within background levels, indicating little ac- cumulation risk for this related species (Bohall- Wood et al. 1996). Though migratory Cooper’s Hawks do not appear to be at significant risk from lead-artifact ingestion in the Rocky Mountain Fly- way, hunting practices and density vary widely in the U.S. and the potential for increased exposure resulting from greater hunting and fishing pres- sures in other regions of the country exists. Addi- tionally, individuals experiencing higher exposure levels may be precluded from successful migration, and may not be identified in studies such as these. Further investigation of a greater variety of raptor species is required before an assessment of the true risks to raptors will be possible. Acknowled gments HawkWatch International banding crews in the Sandia Mountains (A. Peterson, C. Noel Nies, and W. Lehman) and Manzano Mountains (R. Smith, K. Jacobson, D. John- son, K. Bagnall, L. Greenwood, and P. McKann) assisted with animal capture, handling, and sample collections. M. Baird and C. McFarland assisted with laboratory anal- yses. P. Grindrod and W. Sanborn provided useful edi- torial comments. The project described was supported in part by grant No. P42 ES04696 from the National Insti- tute of Environmental Health Sciences, NIH. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the NIEHS or NIH. Funding to support the HawkWatch International banding projects was provided by Cibola National Forest, New Mexico Game and Fish — Share with Wildlife Pro- gram, Intel Corporation, U.S. Fish and Wildlife Service — Region 2, National Fish and Wildlife Foundation, LaSalle Adams Fund, Bureau of Reclamation — Upper Colorado Region, Kerr Foundation, New Belgium Brewing Co., Central New Mexico Audubon, and HawkWatch Inter- national members. Literature Cited Bellrose, EC. 1959. Effects of ingested lead shot upon waterfowl populations. Trans. N.A. Wildl. Conf 16:123- 135. Beyer, W.N., O.H. Pattee, L. Sileo, DJ. Hoffman, and B.M. Mulhern. 1985. Metal contamination in wildlife living near two zinc smelters. Environ. Pollut. 38:63— 86 . Boal, C.W. 1997. An urban environment as an ecological trap for Cooper’s Hawks. Dissertation, Univ. Arizona, Tucson, AZ U.S.A. , K.S. Hudelson, R.W. Mannan, and T.S. Esta- RROOK. 1998. Hematology and hematozoa of adult and nestling Cooper’s Hawks in Arizona. /. 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Periph- eral neuropathy in a Turkey Vulture with lead toxi- cosis. /. Am. Vet. Med. 214:1218-1220. Rosenfield, R.N. and J. Bielefeldt. 1993. Cooper’s Hawk {Accipiter cooperii). In A. Poole and F. Gill [EdS.], The birds of North America, No. 75. Birds of North America, Inc., Philadelphia, PA U.S.A. Sanderson, G.C. and F.C. Bellrose. 1986. A review of the problem of lead poisoning of waterfowl: special publications 4. Illinois Natural History Survey, Cham- paign, IL U.S.A. Scheuhammer, A.M. 1987. The chronic toxicity of alu- minum, cadmium, mercury, and lead in birds: a re- view. Environ. Pollut. 46:263-295. Stahlecker, D.W. and a. Beach. 1979. Successful nesting by Cooper’s Hawks in an urban environment. Inland Bird Banding 51:56— 57 . Stout, LJ. and G.W. Cornweiu. 1976. Nonhunting mor- tality of fledged North American waterfowl. J. Wildl. Manage. 44:525-527. United States Environmental Protection Agency. 1996. Method 3050B: acid digestion of sediments, sludges, and soils. 10 November 2002, www.epa.gov/ epaoswer/hazwaste/ test/ pdfs/3050b.pdf. Wayiand, M., E. Neugebauer, and T. Bolijnger. 1999. Concentrations of lead in liver, kidney, and bone of Bald and Golden eagles. Arch. Environ. Contam. Toxicol. 37:267-272. ZwANK, P.J., V.L. Wright, PM. Siiealy, and J.D. Nelson. 1985. Lead toxicosis in waterfowl on two major win- tering areas in Louisiana. Wildl. Soc. Bull. 13:17-26. Received 1 April 2003; accepted 23 November 2003 Associate Editor: Clint W. Boal J. Raptor Res. 38(2):125-132 © 2004 The Raptor Research Foundation, Inc. AN ASSESSMENT OF CAGE FLIGHT AS AN EXERCISE METHOD FOR RAPTORS Dana M. Greene^ Department of Biology, University of North Carolina, Charlotte, NC 28223 U.S.A. Mathias Engelmann Carolina Raptor Center, RO. Box 16443, Charlotte, NC 28297 U.S.A. Todd R. Steck^ Department of Biology, University of North Carolina, Charlotte, NC 28223 U.S.A. Abstract. — There are a number of methods used for exercising muscles during the rehabilitation of raptors, such as outdoor-creance flight, indoor-hall flight, outdoor-cage flight, and combinations of any of the above. Previous studies measured blood-lactate levels after cessation of exercise to assess muscle fitness and found that creance flight was an effective means of exercise. Physical fitness was inversely correlated with the time it took for postexercise blood-lactate levels to decrease. Using criterion for muscle fitness previously established for creance flight, we examined the effectiveness of caged flight to increase muscle fitness during rehabilitation of six species of raptors: Barn Owl ( Tyto alba) , Barred Owl {Strix varia). Broad-winged Hawk {Buteo platypt^us). Eastern Screech-Owl {Megascops asio). Great Horned Owl {Bubo virginianus) , and Red-tailed Hawk {Buteo jamaicensis). Examination of blood-lactate levels after exercise indicated that caged flight may be sufficient to increase muscle fitness in Great Horned Owls and Broad-winged Hawks and may be a useful method to increase muscle fitness in three of the remaining four raptor species examined. However, there was a difference in the recovery of lactate values related to the type of injury and species of raptor injured, suggesting the effectiveness of flight cages are species specific and that additional rehabilitation techniques, as well as longer rehabil- itation durations may be needed for full recovery. Keywords; Raptor rehabilitation', muscle fitness', cage-flight exercise, creance-flight exercise. UNA EVALUACION DE LAS ENCIERROS DE VUELO COMO UN METODO DE EJERCICIO PARA AVES RAPACES Resumen. — Hay un numero de metodos usados para ejercitar los musculos durante la rehabilitacion de rapaces, tales como el vuelo con fiador en exteriores, el vuelo en un salon interior, el vuelo en un encierro exterior, y combinaciones de algunos de los anteriores. Estudios previos han medido los niveles de lactato en la sangre luego de cesar el ejercicio para evaluar la aptitud del musculo y encontraron que el vuelo con fiador fue un medio efectivo de ejercicio. La aptitud fisica fue correlacionada inver- samente con el tiempo invertido para que los niveles de lactato en la sangre decrecieran despues del ejercicio. Usando un estandar para la aptitud del musculo establecida previamente para el vuelo con fiador, examinamos la efectividad del vuelo en jaula para aumentar la aptitud del musculo durante la rehabilitacion de seis especies de rapaces: Lechuzas {Tyto alba), buhos barrados {Strix varia), gavilanes de ala ancha {Buteo platypterus) , buhos chirreadores orientales {Megascops asio), el gran buho cornado {Bubo virginianus), y gavilanes de cola roja {Buteo jamaicensis) . El examen de los niveles de lactato en la sangre despues del ejercicio indico que el vuelo en jaulas puede ser suficiente para incrementar la aptitud del musculo en buhos cornados y gavilanes de ala ancha y puede ser un metodo util para incrementar la aptitud del musculo en tres de las restantes cuatro especies de aves rapaces examinadas. Sin embargo, no hubo diferencia en la recuperacion de los valores de lactato relacionado con el tipo de lesion y la especie de ave rapaz herida, sugiriendo que la efectividad de las jaulas de vuelo es ^ Present address: University of Alaska Fairbanks, 902 Koyukuk Drive, Fairbanks, AK 99775 U.S.A. ^ Corresponding author’s email address: trsteck@email.uncc.edu 125 126 Greene et al. VoL. 38, No. 2 especifica a la especie y que las tecnicas de rehabilitacion adicionales, al igual que los tiempos de rehabilitacion mas extensos pueden ser necesarios para una recuperacion total. [Traduccion de Cesar Marquez] The goal of raptor rehabilitation is to treat, re- habilitate, and release injured birds of prey into the wild. During convalescence, the skeletal-muscle fitness of a raptor can significantly decline. To im- prove survival after release, muscle fitness should be restored to a degree that would allow a raptor to hunt successfully. However, there is little known about the effectiveness of various exercise methods used by rehabilitators. Several main methods are used for exercising muscles during the rehabilitation of raptors (Chap- lin et al. 1989). Hall flights are performed indoors with the bird flying unrestrained from one perch to another and usually these short flights are re- peated several times. Creance flight is performed by attaching a tether to leather anklets placed on the bird’s legs. The bird is then taken out into a large open field and allowed to fly the length of the tether a number of times as determined by the rehabilitator. Chaplin et al. (1989, 1993) estab- lished that creance flight increases the flight fitness of injured raptors. Hall flight and creance flight are often used together, starting first with hall flights and progressing to creance flight. Another method for rehabilitation is outdoor-cage flights. A raptor that has healed from its injury is placed in an outdoor-flight cage to build muscle strength ini- tially by moving between low perches. Once the raptor is able to move easily between these perches without signs of stress (i.e., panting), it is then moved to a larger flight cage. Flight cages are usu- ally long and narrow with high perches only at the ends in order to encourage full flights from one perch to the next. The cages are also built to spe- cies-specific dimensions (Read 1990). Unlike cre- ance flight, there have been no studies examining the effectiveness of outdoor-cage flight. Wildlife rehabilitation principles include limit- ing human contact to prevent habituating birds to humans to improve their success as independent predators in the wild, and to reduce stress from human contact (Patton and Crawford 1985). There are certain advantages and disadvantages associat- ed with each of the exercise methods mentioned above. The advantages of cage flight are that a bird is handled much less than with creance flight, mul- tiple birds can be exercised at one time and by one rehabilitator, and the exercise can be completed in a matter of minutes. This is beneficial to rehabili- tation facilities dependent upon trained volunteers and a limited staff. However, an advantage of cre- ance flight may be that it allows for longer contin- uous flight, up to 60 m or more, and construction of flight cages is not required. Evaluating these exercise methods requires a means to assess exercise effectiveness. One assess- ment tool used to measure the physical fitness of raptors during their exercise regimen is based on physical fitness being inversely correlated with the time it takes for postexercise blood-lactate levels to decrease (Persson 1983). Lactate is a good indica- tor of overall skeletal-muscle fitness because it re- flects how efficiently the animal is converting glu- cose into energy (Persson 1983). Lactate is increased during exercise when skeletal muscles are forced, by a lack of oxygen, to undergo anaer- obic respiration. The kinetics of the change in blood-lactate levels during and after exercise have been used to inves- tigate the effectiveness of creance flight as a meth- od for rehabilitation of Red-tailed Hawks {Buteoja- maicensis; Chaplin et al. 1989, Mueller and Chaplin 1990). Skeletal-muscle fitness was examined by quantifying the lactate concentration present in the blood at 2-min and 10-min postexercise. These workers found that over a 2-5 wk exercise regimen. Red-tailed Hawks had a decrease in the overall lac- tate concentration present in the blood postexer- cise, indicating that skeletal-muscle fitness was im- proving. A follow-up study using similar criteria found that creance flight was an effective means of rehabilitation for seven additional species of rap- tors: Northern Saw-whet Owl (Aegolius acadicus), Eastern Screech-Owl {Megascops asio), Long-eared Owl (Asio otus), Barred Owl {Strix varia), Great Horned Owl {Bubo virginianus) , American Kestrel {Falco sparverius) , and Northern Harrier ( Circus cy- aneus; Chaplin et al, 1993). As part of Chaplin’s et al. (1993) research, the basal-lactate levels for these species of raptor were established for differing lev- els of exercise using creance flight. Using the muscle-fitness-evaluation method de- scribed by Chaplin et al. (1989), we examined the effectiveness of cage flight to improve the fitness June 2004 Cage Flight as Exercise for Raptors 127 Table 1 . Injuries of raptors used in the study. Raptor Species Injury Type Broad-winged Hawks {N = 4) 2 broken talons Old keel fracture, dehydration, bruising Left eye trauma, bruised left wing Orphaned, no injuries Red-tailed Hawks {N = 7) Eractured right wing (radius) Fractured right wing (humerus) , emaciation Fractured left wing (ulna) Right eye trauma, fractured left tibiotarsus, emaciation Tissue damage left leg, emaciation Fractured right humerus Tissue damage right leg, emaciation Barn Owls {N = 4) Fractured left metacarpals Wound on right wrist Fractured left metacarpals, emaciation Orphaned, no injuries Eastern Screech-Owls (N = 4) Concussion Eye trauma (both eyes) Right eye trauma, concussion Unknown Barred Owls {N = 2) Fractured right ulna, right eye removed, left eye trauma Healed fracture left metatarsus, left eye trauma Great Horned Owls (A^ = 4) Orphaned, no injuries Orphaned, no injuries Emaciation, right leg wound, toe injuries Orphaned, no injuries of injured Red-tailed Hawks, Broad-winged Hawks {Buteo platypterus) , Eastern Screech-Owls, Barred Owls, Barn Owls (Tyto alba) and Great Horned Owls. Methods Exercise Regimen. The injured and orphaned birds used in this study were admitted to the Carolina Raptor Center and confined to indoor cages for 3-30 wk during injury treatment (Table 1). Raptors were then placed in small outdoor cages (3 m X 5 m X 3 m) containing multiple perches of varying heights (0.3-1. 6 m tall). Birds were fed a diet of either rats (Rattus norvegicus) or mice (Mus musculus) 6 d/wk. They were moved to a flight cage after they were able to move among the low perches without difficulty, and based upon inspection of respira- tion and feather condition. Only raptors of the same spe- cies were housed together in flight cages, with 6—8 birds per cage. The flight cages were species specihc (Table 2), and large enough to accommodate flight during the en- tire period of rehabilitation. The flight cages at the Car- Table 2. Approximate cage and perch measurements for selected rehabilitation cages. Each species of raptor studied were housed in outdoor flight cages for the 3 wk of study. Dimensions within each cage are variable because ground slopes in most cases, leaving one end of the cage taller than the other. Perches represent the tallest available to birds and the ones they select most of the time while exercising. Raptor Housed Cage Dimensions Ground-to- Perch Perch-to- Ceiling Broad-winged Hawks 14 m L X 3 m W X 3.5 m H 2.5 m 1 m Barn Owls 17 m L X 3 m W X 3.5 m H 2.5 m 1 m Barred Owls IVmLX 3mWX 3.5 m H 2.5 m 1 m Eastern Screech-Owls 10.5 mLX3mWX3mH 2.5 m 0.5 m Red-tailed Hawks 27.5 m L X 4.5 m W X 4.5 m H 3 m-3.5 m 1 m-1.5 m Great Horned Owls 14mLX 3mWX 3.5 m H 2.5 m-3 m 1 m-1.5 m 128 Greene et al. VoL. 38, No. 2 Table 3. Slopes of lactate concentrations for six species of raptors with and without inclusion of orphans over a 3- 5 wk exercise period. Raptor samples with no orphans are indicated with N/A. Data with All Birds Data without Orphans Raptor Species 2-min 10-min 2-min 10-min Red-tailed Hawks (N= 7) -1.87 -6.79 N/A N/A Great Horned Owls (N = 4), no orphans (N = 1) -12.02* -15.28* -16.18" -39.08" Barred Owls (N= 2) 10.25 12.63 N/A N/A Barn Owls (N = 4), no orphans (N = 3) 0.58 7.96 -5.48 5.74 Broad-winged Hawks (N = 4), no orphans (N = 3) -22.04 3.44 -36.66* 0.24 Eastern Screech-Owls (N= 4) -9.45 -4.12 N/A N/A Indicates a significant decrease in lactate concentrations (P ^ 0.05). ^ Indicates no analysis was possible because there was only one Great Horned Owl in this group. olina Raptor Center were built based upon the experi- ence of the rehabilitators, and built as large as possible based on the birds’ needs and available funding. The perches were situated high at opposite ends to encourage full flights the length of the cage (Table 2). Once the birds acclimated to their surroundings (2-5 d), they were exercised daily by a rehabilitator walking from one end of the cage to the other end, encouraging the birds to fly. The numbers of flights were gradually increased by 2-5 flights per wk, depending on the species of raptor and the rehabilitator’s opinion of the individual fitness of each bird at the beginning of the regimen. Re- spiratory rate, feather condition, and flight form were used as indices of physical fitness. Red-tailed Hawks were initially exercised by flying 8-10 laps/d (one lap is equiv- alent to flight from one end of the cage and back to the starting point) and increased to 20 laps/d by the end of their recovery (3-5 wk) before release. Rest time was kept to a minimum (less than 15 sec) between laps. Broad- winged Hawks began with 5—8 laps, which was increased to 15 laps. Barn Owls, Barred Owls and Great Horned Owls began with 4—6 laps, which were increased to 10 laps. The criteria used for increasing a bird’s exercise regimen (increasing laps) was determined by the num- ber of laps each bird could fly without rapid respirations (panting) and if the bird was able to make full flights between perches. Blood-Lactate Level Determination. Once a wk the birds were caught using a large net. Capture was per- formed immediately after exercise in order to prevent additional flights and to ensure all birds in the same cage had the same number of flights. After capture, the birds were dorsally restrained in weight wrappers that enclosed their body and covered their heads so that the birds re- mained calm and immobile throughout the subsequent procedure (Engelmann and Marcum 1993, Miller 2000). For this assessment, it is imperative to keep stress levels to a minimum because lactic-acid values can increase due to stress. Blood samples were drawn from the brachial veins at 2-min postexercise and then at 10-min postex- ercise. In the time between blood sampling, stress levels were reduced by keeping the birds covered and motion- less in a quiet environment. Whole blood (0.02-0.10 ml) was stored on ice for up to 1 hr prior to extracting pro- teins using twice the volume of 8% perchloric acid. Sam- ples were then centrifuged for 10 min at 2700 X g. The supernatant (clear) was removed and kept at 4°C for up to 10 d until performing the lactate assay. The lactate assay was performed per manufacturer’s instructions using the Lactate Diagnostic Kit (Sigma Chemical Co., St. Louis, MO U.S.A.), using a Benchmark Microplate Reader (Bio-Rad Laboratories, Hercules, CA U.S.A.) and Microplate 5.2 data analysis software (Bio- Rad Laboratories, Hercules, CA U.S.A.). Data Analysis. Data were analyzed by linear regression, and the means of the 2-min and 10-min lactate values were analyzed using a one way Analysis of Variance (AN- OVA), followed by Tukey’s studentized range test, when appropriate (SAS statistical software, version 5.0, Cary, NC U.S.A.). Results The rate of the decrease in blood lactate over the 3—5 wk exercise period for six species of raptors is indicated by the slope of the regression line through each of the averaged lactate values for the 2-min and the 10-min postexercise times (Fig. 1). A negative slope of the regression trend line would suggest an increase in skeletal-muscle fitness. Four (including orphans) or five (excluding or- phans) of the six raptor species examined exhib- ited a decrease in overall blood-lactate concentra- tions at one of the time points over the 3-5 wk 129 June 2004 Cage Flight as Exercise for Raptors A Red-tailed Hawks Great Homed Owls t=i o is S o § U o o as Barred Owls Barn Owls Time Figure 1. Change in lactate concentrations for six species of raptors over an exercise period (see Methods). Blood- lactate levels were measured postexercise at 2-min ( ♦ ) and 10-min ( 0 ) intervals. Data are expressed as the overall blood-lactate levels at the end of each wk, and regression lines (gray solid lines) were calculated to represent the mean change in blood-lactate concentration over time. Panel A — Red-tailed Hawks {N = 7). Panel B — Great Horned Owls (N = 4). Panel C — Barred Owls (N = 2). Panel D — Barn Owls (N = 3) regression data exclude one orphan. Panel E — Broad-winged Hawks {N = 3) regression data exclude one orphan. Panel F — Eastern Screech-Owls. exercise period (Table 3) . Great Horned Owls had a significant decrease in their lactate values (P = 0.03, p23,.^ ~ 4.18, N = 4; Fig. IB). Eastern Screech- Owls had a decrease in both their lactate values; however, the decrease did not reach significance (P - 0.17, P23.5 = 1-91, 4; Fig. IF). Red-tailed Hawks had a decrease in both the 2-min and 10- min values, but again this pattern was not signifi- cant (P = 0.40, P41 5 - 0.95, 7; Fig. lA). Broad- winged Hawks showed a decrease in their 2-min values, but not in their 10-min values; the decrease was not significant (P = 0.25, Pgs.s ~ 1.50, N — 4; Fig. IE). However, when the orphaned raptor in this group was removed, the decrease in lactate at 2-min was significant (P = 0.05, P17 5 = 3.86, N — 3) . There was also a significant interaction between the 2-min and 10-min lactate values (P= 0.05, = 3.98, N — 3); analysis of the treatment weeks showed that wk 1 and wk 3 were significantly dif- ferent from each other for the 2-min lactate values (P 0*05) j but riot for the 10“miri l3,ct^te V3.1ues (P > 0.05) (Fig. IE, Table 3). Barn Owls did not 130 Greene et al. VoL. 38, No. 2 Table 4. Effectiveness of cage flight is influenced by injury type. Linear regression slopes were calculated based on injury type for each species group. One injury or mild injuries include broken talons, tissue damage, mild concussion, or non-blinding eye traumas. Multiple injuries or severe injuries include fractures that are accompanied with other injuries such as emaciation, tissue damage, and eye trauma or eye removal. N/A denotes no birds qualified for this sample group. Raptor Species One Injury or Mild Injuries Multiple Injuries or Severe Injuries Orphaned with No Injuries 2-min 10-min 2-min 1 0-min 2-min 1 0-min Red-tailed Hawks -17.64 -8.28 32.55 7.98 N/A N/A N 5 5 2 2 Great Horned Owls -12.02 -15.28 N/A N/A -1.48 -2.63 N I 1 3 3 Barred Owls N/A N/A 10.25 12.63 N/A N/A N 4 4 Barn Owls -5.47 -5.74 N/A N/A 18.75 14.63 N 3 3 1 1 Broad-winged Hawks -36.66 0.24 N/A N/A 21.80 13.05 N 3 3 1 1 Eastern Screech-Owls -9.45 -4.12 N/A N/A N/A N/A N 4 4 show a decrease in lactate values over time (P = 0.46, 7^23 5 = 0.82, N — 4). When the orphan in this group was removed, the 2 -min lactate value de- creased, giving a negative regression slope, but this trend was not significant {P = 0.58, 7^7 5 = 0.55, N = 3; Fig. ID, Table 3). Barred Owls showed a slight nonsignificant increase in lactate values (P — 0.05, 7^15.7 ^ 4.01, 2; Fig. 1C). Discussion Our results indicated that the use of flight cages as a form of rehabilitation exercise may be an ad- equate method for increasing skeletal-muscle fit- ness and improving aerobic conditioning of cer- tain species of injured raptors. Of the six raptor species studied, five exhibited a negative linear-re- gression slope in at least one of the two time points studied (Table 3) . The Great Horned Owls showed a statistically significant improvement in lactate re- covery with cage flight, indicating that cage flight was sufficient to improve muscle fitness in this spe- cies. Red-tailed Hawks and Eastern Screech-Owls showed decreases in both 2 -min and 10 -min lactate values; however, these trends were not significant. Broad-winged Hawks and Barn Owls (excluding or- phans) showed a decrease in the 2 -min time lactate values, but these trends were not significant. Fur- ther analysis of the Broad-winged Hawks that in- volved exclusion of the orphaned raptor resulted in a significant decrease in the lactate values, sug- gesting that cage flight is useful for the adult in- jured raptors of this species. These data indicated that use of cage flight may be a valuable method to improve muscle fitness in certain species, such as the Great Horned Owls and Broad-winged Hawks, but may need to be combined with other rehabilitation methods in other species. Chaplin et al. (1989) proposed guidelines for 2- min and 10 -min lactate values postexercise for cre- ance rehabilitation of certain species (e.g., screech- owls, Great Horned Owls, Red-tailed Hawks). The lactate values of the cage-exercised raptors were comparable to the guidelines set by Chaplin (1989); however, the decreases were not as dra- matic as seen in this earlier work. There are several reasons that may account for this difference. In flight cages, there was a possibility the raptors did not obtain enough sustained wing flaps, probably coasting to the other perch involving less muscle exertion. Coasting was not observed by the reha- bilitators during this study; however, there was a short rest period between flights, which was kept to a minimum (the time for a rehabilitator to walk from one end of the cage to the other; <15 sec). This rest period may account for the decreased ef- fectiveness of the flight cages for these raptors. Fu- ture studies should be performed that reduce or eliminate this rest time. June 2004 Cage Flight as Energise eor Raptors 131 The difference in response of raptors of differ- ent species may also be due to differing wing me- chanics and hunting behaviors. Great Horned Owls are a perch-and-watch predator and once prey are detected, they pursue their prey by de- scent or a short-sprint flight. Cage flight may du- plicate these hunting flights and could be the rea- son that the Great Horned Owls responded well to this method of rehabilitation. Other species that are more endurance fliers when hunting, such as Barn Owls, may need longer sustained flights for skeletal-muscle improvement. In this case, cage flight may be a good preliminary exercise method for these species, if it is then followed by other methods such as creance flight. One confounding factor in this study was the ex- tent of injuries sustained by the raptors (Table 1). The greater number and more complex the inju- ries sustained, the raptors were less responsive to exercise (Table 4). Raptors with multiple and se- vere injuries tended to have a positive linear-re- gression slope for the lactate concentrations over time, as compared to those with one injury or mild injuries, which had negative slopes (Table 4) . The differences in injury types may contribute to the variation of responses in the other raptor species, as well as the lack of response to treatment in the Barred Owls, which had severe injuries. In cases of severe injuries, cage flight may be suitable as a pre- liminary form of exercise. However, it may be nec- essary to exercise the birds for a longer duration than used in this experiment and use other exer- cise methods, such as creance flight. A third, perhaps related, factor was whether the raptor was an orphan. Orphaned raptors did not show an increase in muscle fitness. This may be due to a lack of injuries, and an absence of prior flight experience. The raptor orphans in this study tended to have shallower negative linear lactate re- gression slopes, or positive slopes as compared to the adult raptors rehabilitated for mild injuries (Table 4). The Broad-winged Hawks demonstrate this pattern. The adult Broad-winged Hawks showed a significant decrease in lactate values, but the orphaned hawk of this species did not show improvement with cage flight. These results are similar to previous research that compared lactate dehydrogenase kinetics between untrained and previously flight-trained Rock Pigeons ( Columba liv- ia) that were either cage confined, or wing re- strained for several wk before retraining (Chaplin et al. 1997). The untrained Rock Pigeons had slow- er clearance of lactate than did the trained birds, which was similar to what we observed with the orphaned raptors (Table 4). Our results indicated that raptor orphans may need special flight train- ing and for a longer duration than injured adults. We note that the sizes of the flight cages are im- portant when replicating these findings. The sizes of the flight cages used in this study were deter- mined by the rehabilitation staff at the Carolina Raptor Center based upon previous experience with these raptor species, as well as the amount of available funds. Most of the flight cages were built larger than many current guidelines set forth by the National Wildlife Rehabilitation Association and International Wildlife Rehabilitation Council for unlimited activities (Eastern Screech-Owl, 2.4 m X 2.4 m X 2.4 m; Barn Owl, 3 m X 9 m X 3.6 m; Barred Owl 3 m X 15.2 m X 3.6 m; Great Horned Owl 3 m X 15.2 m X 3.6 m; Broad-winged Hawk, 3 m X 9 m X 3.6 m; and Red-tailed Hawk, 3 m X 15.2 m X 3.6 m; Miller 2000). The fitness criteria used in this study are proposed by Chaplin et al. (1989, 1993) and represent a standard deter- mined using falconry-trained Red-tailed Hawks. This standard may differ for other types of raptors, especially those with very different wing mechanics and flight habits. Acknowledgments We thank the many volunteers at the Carolina Raptor Center who assisted with this research, and Dr. Robert Bierregaard, Dr. Marina Castillo, Dr. Abel Bult-Ito, Pat Rivera, Ron Tavernier, and the two manuscript referees for invaluable comments. This work was supported by a Ronald E. McNair Post-Baccalaureate Achievement Pro- gram Scholarship (to D. Greene). Literature Cited Chaplin, S.B., L. Mueller, and L. Degernes. 1989. Phys- iological assessment of rehabilitated raptors prior to release. Wildl. J. 12:7—18. , , AND . 1993. Physiological assess- ment of flight conditioning of rehabilitated raptors. Pages 167-173 in P.T. Redig [Ed.], Raptor biomedi- cine. Univ. Minnesota Press, Minneapolis, MN U.S.A , M.M. Munson, and S.T. Knuth. 1997. The effect of exercise and restraint on pectoral muscle metabo- lism in pigeons./. Comp. Physiol. 167:197-203. Engelmann, M. and P. Marcum. 1993. Raptor rehabili- tation: a manual of guidelines offered by the Carolina Raptor Center. Carolina Raptor Center, Charlotte, NC U.S.A. Miller, E.A. (Ed.). 2000. Minimum standards for wildlife rehabilitation, 3rd Ed. National Wildlife Rehabilita- tors Association, St. Cloud, MN U.S.A. 132 Greene et al. VoL. 38, No. 2 Mueller, L.R. and S.B. Chaplin. 1990. Flight condition- ing in raptors; a physiological test of aerobic fitness. WildlRehab. 8:135-141. Patton, K.T. and W.C. Crawford, Jr. 1985. Stress in cap- tive birds of prey. Wildl. Rehab. 4:43-48. Persson, S.G.B. 1983. Evaluation of exercise tolerance and fitness in the performance horse. Pages 441-457 in D.H. Snow, S.G.B. Persson, and J.R. Rose [Eds.], Equine exercise physiology. Burlington Press, Gam- bridge, U.K. Read, N. 1990. Species specific cage design for raptors. WiUl Rehab. 8:73-80. Received 1 November 2002; accepted 13 February 2004 Associate Editor: Ian G. Warkentin J. Raptor Res. 38(2): 133-1 40 © 2004 The Raptor Research Foundation, Inc. MODELING HABITAT USE AND DISTRIBUTION OF HEN HARRIERS {CIRCUS CYANEUS) AND MONTAGU’S HARRIER ( CIRCUS PYGARGUS) IN A MOUNTAINOUS AREA IN GALICIA, NORTHWESTERN SPAIN Luis Tapia^ and Jesus Dominguez Dpto. de Bioloxia Animal, Facultade de Bioloxia, Universidad de Santiago de Compostela, Campus sur, s/n, 15782 Galicia, Spain Luis Rodriguez Dpto. de Edafoloxia e Quimica agricola, Facultade de Bioloxia, Universidad de Santiago de Compostela, Campus sur, s/n, 15782 Galicia, Spain Abstract. — To evaluate the effect of habitat characteristics on the sympatric populations of Hen Har- riers {Circus cyaneus) and Montagu’s Harriers {Circus pygargus) , we have developed predictive models (logistic regression) for the presence/ absence and distribution of harriers in the Site of Community Importance Baixa-Limia, northwestern Spain. We have used habitat and topographical variables mea- sured on digital 1:50 000-scale cartography. We have developed spatial prediction on suitable habitat availability for harriers by means of Geographical Information System Analysis of 2 X 2 km plots. The final models explained 11% of the variance for Hen Harrier, 18% of the variance for the Montagu’s Harrier, and 12% of the variance for both species simultaneously. Altitude was a variable that influenced the presence of both harrier species, which were more common over 800 m. The presence of Montagu’s Harrier in a plot was positively associated with the presence of gradual relief of Atlantic heathland. The most important threats to harrier populations are human infrastructures (e.g., roads, tracks), prolifer- ation of human activities such as afforestation and intense deliberate wild-fires that change the habitat conditions for both species. Key Words: Hen Harrier, Circus cyaneus; Montagu’s Harrier, Circus pygargus; habitat use, modeling, Spain. MODELIZACION del USO del hAbITAT Y DISTRIBUCION del AGUILUCHO PALIDO {CIRCUS CYANEUS) Y AGUILUCHO CENIZO {CIRCUS PYGARGUS) EN UN ArEA MONTANOSA DE GALICIA (NO ESPANA) Resumen. — Con el objetivo de evaluar el efecto de las caracteristicas del habitat sobre poblaciones simpatridas de aguilucho palido ( Circus cyaneus) y aguilucho cenizo ( Circus pygargus) , desarrollamos modelos estadisticos predictivos (Analisis de Regresion Logistica) para la presencia/ausencia y distri- bucion de los aguiluchos en el LIC (Lugar de Interes Comunitario) Baixa-Limia (NO Espana) . Usamos variables ambientales medidas sobre cartografia digital a escala 1:50 000, utilizando un Sistema de In- formacion Geografica con la reticula de 2 X 2 km. Los modelos finales explicaron un 1 1 % de la varianza para el aguilucho palido, un 18% para el aguilucho cenizo y un 12% para ambas especies simultanea- mente. La altitud fue un factor que influyo en la presencia de ambas especies, siempre por encima de 800 m. La presencia de aguilucho cenizo en una cuadricula se relaciono positivamente con la presencia de areas con relieve suave de brezal atlantico. Las amenazas mas importantes son infraestructuras como carreteras y pistas de tierra, repoblaciones y grandes incendios forestales intencionados, modificadores de las condiciones del habitat de ambas especies. [Traduccion de los autores] Determination of the variables that influence most important objectives of ecology (Cody 1985, the distribution of species has been one of the Wiens 1989). Studies of habitat selection have tra- ditionally analyzed the relations of one species rel- ative to the characteristics of its habitat; often lead- ^ E-mail address: baltapia@usc.es ing to the development of predictive models 133 134 Tapia et al. VoL. 38, No. 2 (Morrison et al. 1998). These models are particu- larly important in efforts to preserve threatened species, as for example in the case of some Iberian raptor species (e.g., Donazar et al. 1993, Gil-San- chez et al. 1996, Bustamante 1997, Sanchez-Zapata and Calvo 1999), even though they are not exempt from severe limitations (Fielding and Haworth 1995, Beutel et al. 1999, Seoane and Bustamante 2001). Raptors are usually highly selective with re- gard to their habitat, especially regarding the avail- ability of suitable areas for breeding and hunting (Janes 1985). The spatial scale involved is important to under- standing the implications and limitations of pre- dictive models (e.g., Litvaitis et al. 1994, Pribil and Pieman 1997, Rotenberry and Knick 1999, Mitchell et al. 2001). In this respect, the models on scales similar to or greater than the home range seem to establish relations amongst raptors with regard to the selection of macrohabitat and associations with ecosystem mosaics (Sanchez-Zapata and Calvo 1999, Rico-Alcazar et al. 2001). The Hen Harrier (Circus cyaneus) and the Mon- tagu’s Harrier (Circus py gar gus) have declining pop- ulations in Europe (Tucker and Evans 1997). On the Iberian peninsula, these harriers usually use ce- real crop lands as nesting habitat (Ferrero 1996), even though in the northwestern part of the pen- insula they usually breed in areas of natural vege- tation (Pinilla et al. 1994, Vazquez-Pumariho 1995, Ferrero 1996). Studies of habitat selection and pre- dictive modeling for these species are scarce, both for the European continent and in the Iberian peninsula (Salamolard 1997, Martinez et al. 1999, Madders 2000). In Galicia (northwestern Spain), both harrier species are sympatric, occurring in an area dominated by Atlantic-heathland shrubs. The objective of the present study was to estab- lish models of habitat selection using the infor- mation obtained from an atlas of nesting birds. The atlases of the distribution of species are very limited with respect to the information they pro- vide (Donald and Fuller 1998, Sutherland 2000), but they may be used as a very important source of information to create predictive models of dis- tribution for different species of vertebrates (e.g., Osborne and Tigar 1992, Jaber and Guisan 2001, Rojas et al. 2001). These models will become a tool which will contribute to the management of a pro- tected area relating to two high priority species in- cluded in Annex I of the Birds Directive 79/ 409/ 79 European Economic Community. Annex I lists species of birds in Europe which are of priority for habitat conservation (Tucker and Evans 1997). Study Area and Methods The study area is 40 000 ha, the majority of which (34 627 ha) is the Site of Community Importance (SCI) Baixa Limia. It extends along the southwestern sierras of the province of Ourense, bordering the National Portu- guese Park of Peneda-Geres (Fig. 1). Both protected ar- eas, the Spanish and the Portuguese, cover in total an area of 106 627 ha. It is a mountain range of medium altitude, with sum- mits of up to 1500 m, comprised predominantly of gran- ite rocks. Currently, human population in the area is quite low, even though the landscape has been intensely affected by human actions. From the climatic point of view, this area has a temperate sub-Mediterranean oce- anic climate of 8-1 2°C, with an annual precipitation of 1200-1600 mm, and a significant water shortage in the summer (Martinez- Cortizas and Perez-Alberti 1999). The most common types of vegetation are the shrub com- munities (Ulex sp., Chamaespartium tridentatum, Erica sp., Genista sp., and Cytisus sp.), which constitute the greatest percentage of vegetation. Woods are very fragmented, and are dominated by oaks (Quercus robur, Q. pyrenaica) and pines (Pinus pinaster, P. sylvestris) . All plant commu- nities in the study area are impacted by frequent delib- erate fires, sometimes affecting large areas. The harrier’s distribution in the study area was ob- tained from field work carried out in the spring seasons, 1997-2000. This work consisted of systematic surveys throughout the study area, although the entire study area was only covered in spring 2000 considering the sampling effort necessary for the detection of harrier species (Pin- illa and Arroyo 1995). Evidence of occupancy by a nest- ing harrier included; a nest containing eggs or young, adults seen carrying food, and hearing the begging calls of young birds (Bibby et al. 1992). With the help of Glob- al Positioning System (GPS), all the observations were located in the corresponding 1X1 km square (maps 1: 25 000) . This sampling was carried out with the aim of completing an atlas for breeding harriers. Harrier’s presence for any breeding category was the dependent variable used in the analysis (Hagemeijer and Blair 1997). Breeding categories included: possible breeding (harriers observed in potential nesting habitat) , probable nesting (pair observed in suitable nesting hab- itat, courtship, display, or nest building) and confirmed breeding (nest contained eggs or young) (Hagemeijer and Blair 1997). Presence was obtained from the final distribution atlas, derived from cumulative observed data for the 1997—2000 period. Atlas data indicated that the local Montagu’s Harrier population in Baixa-Limia was 15-20 pairs, and the Hen Harrier population was 8-10 pairs. For the analysis of habitat selection a 2 X 2 km grid was used, integrating the information obtained in the 1 X 1 km squares. The 2X2 km squares which had less than 50% of their surfaces within the limits of the SGI or more than 50% in Portugal were discounted. For anal- ysis we used the 2X2 km grid, due to the low proportion of grid squares in which harriers were present based on a 1 X I km grid, and also because the cartography used June 2004 Habitat Use in Harriers 135 Figure 1. Study site (Baixa Limia) in Galicia (northwestern Iberian peninsula). lost resolution at small scales (Sanchez-Zapata 1999, Zu- berogoitia 2002). The independent variables were selected because they represented different uses of the land, degree of human- ization, topographic irregularity, and habitat heteroge- neity (Table 1), and values for each variable were as- sumed for each 2X2 plot studied. The information relating to the different environmental variables was tak- en from 1:50000 digital cartography via a Geographic Information System (GIS-ArcView 3.1, Environmental Systems Research Institute, Inc., Redlands, CA U.S.A.). The digital cartography used had a resolution of 250 X 250 m. Continuous variables (i.e., slope and altitude) were ob- tained from analysis of the variable of each square using a digital elevation model with a resolution of 250 X 136 Tapia et al. VoL. 38, No. 2 Table 1. Independent variables included in the logistic regression for the habitat models of Hen Harrier and Montagu’s Harrier in the Site of Community Importance Baixa-Limia. Label Description of the Variable No. settlements Number of human settlements Area of settlements Area of human settlements Road length (m) Length of paved roads Mm. altitude (m) Minimum altitude Max. altitude (m) Maximum altitude Max.-min. altitude (m) Maximum altitude-minimum altitude Mean altitude (m) Average altitude Mm. slope (grades) Minimum slope Max. slope (grades) Maximum slope Max.-min. slope (grades) Maximum slope-minimum slope Mean slope (grades) Average slope Scrub-pasture area (km^) Area of scrubland and pastureland Forest area (km^) Area of forests Dam area (km^) Area of dams Scrub-forest edge (m) Meters of edge between scrubland-forests Scrub-dam edge (m) Meters of edge between scrubland-dam Forest-dam edge (m) Meters of edge between forest-dam 250 m. The remaining variables were obtained directly with CIS using vectorial data. Scrubland and pasture sur- faces are often intermixed. They were treated as one cov- er type because they could not be distinguished at the spatial resolution used. All forest types were also treated as the same variable independent of their tree species composition. Forests and scrubland-pastures represented close to 90% of the total study area. A Mann-Whitney Latest was used to establish which var- iables were significantly different between plots in which both species (independently) were present or absent. Those variables that showed significant differences were included in the stepwise-logistic regression analysis (Jov- ell 1995). The significance of the variables included in the final regression model was determined by the Wald test (Jovell 1995). The level of signihcance used was P < 0.05. We used SPSS package (SPSS II, McGraw-Hill, Ma- drid, Spain) for statistical analysis. Results Within the study area, the Hen Harrier was de- tected in 62 l-km^ plots of 397 (15.6%) and in 32 4-km^ squares of 93 (34.4%). With regard to the Montagu’s Harrier, its presence was detected in 123 1-km^ plots (31%), and in 60 4-km^ plots of 2 X 2 km (64%). Both species were detected in 31 l-km2 (7.8%), and in 27 4-km2 plots (29%). At the 4-km^ plot scale, the areas occupied by the Hen Harrier differed from the unoccupied ones in that the former had fewer human settle- ments. Hen Harrier plots were located at higher altitudes and on more gradual slopes than unoc- cupied squares (Table 2) . For the Montagu’s Har- rier, occupied plots had a greater extent of scrub- land and were located significantly higher than unoccupied squares (Table 3) , although they were rarely present above 1000 m above sea level. Considering both species simultaneously, the ar- eas occupied differed from the unoccupied ones in that the former had fewer human settlements. Also, occupied plots were located at greater alti- tude and more gradual slopes than the unoccupied squares (Table 4). The analysis of logistic regression only included the variables of minimum altitude for both species and scrubland and pastureland area for the Mon- tagu’s Harrier; both related positively to occupan- cy. For both species simultaneously, the model in- cluded minimum altitude related positively to occupancy (Table 5). The final model developed for the Hen Harrier was: occupancy — 1/1 + altitude)^ explained 11% of the variance. The overall correct classification was 65.6%. The final model developed for the Montagu’s Harrier was: occupancy = 1/1 + 02.81 8-4.96xlO-7(Scrub and pasture area) -0.00.S( min altitude) ex- plained 18% of the variance. The overall correct classification was 64.5%. The final model developed for both species simultaneously was: occupancy = 1/1 + 03.359-0.003 (min altitude)^ explained 12% of the vari- ance. The overall correct classification was 71%. June 2004 Habitat Use in Harriers 137 Table 2. Comparison of mean values of variables, using Mann-Whitney tests, in 2 X 2 km plots occupied and unoccupied by Hen Harrier in the Site of Community Importance Baixa-Limia (Mean ± SD). Occupied Unoccupied Squares Squares Label 2 X 2 km (N = 32) 2 X 2 km (N= 61) U P No. settlements 0.1563 H- 0.5741 0.4262 0.8054 782.0 0.03U Area of settlements 6073 + 26 763 24440 + 52 130 774.5 0.026* Road length (m) 374 + 737 887 H- 1314 812.0 0.131 Mm. altitude (m) 831 H- 176 695 -+- 244 606.0 0.003** Max. altitude (m) 1165 -+- 131 1077 -h 228 707.0 0.030* Max.-min. altitude (m) 334 -+- 120 381 + 138 732.0 0.048* Mean altitude (m) 1009 + 151 889 243 651.0 0.009** Mm. slope (grades) 0.24 + 0.17 0.31 0.23 826.5 0.227 Max. slope (grades) 32.36 7.47 35.27 -+- 9.94 756.5 0.076 Max.-min. slope (grades) 33.11 -h 7.38 34.95 -h 9.9 768.0 0.093 Mean slope (grades) 9.47 3.31 10.93 3.67 681.5 0.017* Scrub-pasture area (km^) 2.94 + 0.92 2.63 0.95 785.5 0.131 Forest area (km^) 0.75 0.80 0.92 -h 0.87 876.0 0.419 Dam area (km^) 0.03 -+- 0.13 0.12 H- 0.42 909.0 0.314 Scrub-forest edge (m) 10978 -+- 7518 11 731 -+- 9073 953.5 0.856 Scrub-dam edge (m) 110 -h 538 488 + 1496 919.0 0.369 Forest-dam edge (m) 37 212 123 H- 447 895.0 0.178 * Significandy different at P < 0.05. ** Significantly different at P < 0.01. Table 3. Comparison of unoccupied by Montagu’s mean values of variables, using Mann-Whitney tests, in 2 X 2 km plots occupied and Harrier in the Site of Community Importance Baixa-Limia (Mean ± SD) . Label Occupied Squares 2 X 2 (N = 60) Unoccupied Squares 2 X 2 (N= 33) U P No. settlements 0.2667 ± 0.7334 0.4545 ± 0.7538 828.5 0.075 Area of settlements 14 055 ± 39 823 25 510 ± 54 765 827.0 0.074 Road length (m) 571 ± 1056 964 ± 1334 844.0 0.181 Min. altitude (m) 793 ± 212 650 ± 238 654.0 0.007** Max. altitude (m) 1145 ± 176 1039 ± 234 746.0 0.050* Max.-min. altitude (m) 352 ± 134 389 ± 130 820.0 0.172 Mean altitude (m) 978 ± 198 844 ± 241 683.0 0.014* Mm. slope (grades) 0.28 ± 0.22 0.31 ± 0.21 880.5 0.379 Max. slope (grades) 33.33 ± 10.04 35.97 ± 7.35 799.0 0.125 Max.-min. slope (grades) 33.05 ± 9.98 35.66 ± 7.33 802.5 0.132 Mean slope (grades) 10.02 ± 3.70 11.17 ± 3.34 803.5 0.134 Scrub-pasture area (km^) 2.89 ± 0.90 2.46 ± 0.99 701.0 0.020* Forest area (km^) 0.79 ± 0.79 1.0 ± 0.94 836.0 0.216 Dam area (km^) 0.08 ± 0.33 0.11 ± 0.4 969.0 0.754 Scrub-forest edge (m) 11002 ± 8227 12 326 ± 9139 908.0 0.510 Scrub-dam edge (m) 296 ± 1122 471 ± 1494 951.0 0.547 Forest-dam edge (m) 69 ± 271 139 ± 534 979.0 0.856 * Significantly different at P < 0.05. ** Significantly different at P < 0.01. 138 Tapia et al. VoL. 38, No. 2 Table 4. Comparison of mean values of variables, using Mann-Whitney test, in 2 X 2 km plots occupied and un- occupied by both species simultaneously in the Site of Community Importance Baixa-Limia (Mean ± SD). Label Occupied Squares 2 X 2 (A = 27) Unoccupied Squares 2 X 2 (A = 66) U P No. settlements 0.1481 ± 0.6015 0.4091 ± 0.7840 706.0 0.032* Area of settlements 7074 ± 29 103 22 639 ± 50 485 703.5 0.030* Road length (m) 432 ± 790 825 ± 1282 785.0 0.307 Min. altitude (m) 847 ± 178 699 ± 237 515.0 0.001** Max. altitude (m) 1164 ± 139 1084 ± 222 660.0 0.051 Max.-min. altitude (m) 317 ± 118 384 ± 135 581.0 0.009** Mean altitude (m) 1016 ± 155 895 ± 236 582.0 0.009** Min. slope (grades) 0.22 ± 0.16 0.32 ± 0.23 664.5 0.055 Max. slope (grades) 31.19 ± 7.21 35.53 ± 9.7 600.5 0.014* Max.-min. slope (grades) 30.97 ± 7.15 35.20 ± 9.66 613.0 0.019* Mean slope (grades) 9 ± 3.25 11.01 ± 3.60 531.5 0.002** Scrub-pasture area (km^) 2.74 ± 0.95 2.67 ± 0.96 751.5 0.238 Forest area (km^) 0.80 ± 0.85 0.89 ± 0.85 825.0 0.576 Dam area (km®) 0.04 ± 0.15 0.11 ± 0.41 849.0 0.509 Scrub-forest edge (m) 11508 ± 7863 11457 ± 8854 863.5 0.816 Scrub-dam edge (m) 130 ± 585 451 ± 1443 856.5 0.569 Forest-dam edge (m) 44 ± 230 113 ± 431 830.0 0.288 * Significantly different at P < 0.05. ** Significantly different at P < 0.01. Discussion The Hen Harrier had a strong tendency to oc- cupy relatively-level areas in higher altitude of the study area, dominated by Atlantic-heathland vege- tation with scarce human presence. These harriers did not have a tendency to occupy heterogeneous habitats at the scale examined. At finer scales, in- dividuals may be influenced by the structure of shrub formations within their home ranges, when exploiting different trophic resources (Preston 1990, Madders 2000). The Montagu’s Harrier seemed to show a pref- erence for natural shrub formations (e.g., Ahcdsp., Ulex sp., Cytisus sp. and pasture), just as in other areas of the northwestern Iberian peninsula (Vaz- quez-Pumarino 1995), where there was a lack of large areas of cereal cultivation. Our data also in- dicated a tendency for Montagu’s Harriers to occur in zones of higher altitude. For both species simultaneously, the final logistic model included only one variable, minimum alti- tude. This result suggests that preserving the nat- ural Atlantic-heathland vegetation above 800 m may aid in the conservation of the harrier popu- lations of the Baixa-Limia, as well as those in other mountain range areas in Galicia. A greater part of the harrier population in northwestern Spain de- pends on this habitat, which together with the de- cline of many European populations (Etheridge and Hustings 1997, Krogulec 1997), justifies the need for habitat management to improve species viability. The frequency of deliberate small fires in the heathland areas studied, particularly during winter, may favor the creation of a mosaic of scrub types, with bordering areas which might provide suitable habitat for these and other raptors (Dodd 1988, Kochert et al. 1999). On the other hand, the pro- liferation of intense fires, particularly in spring and summer, may endanger nesting and cause declines of some prey species (Camprodon and Plana 2001 ). The abundant presence of livestock grazing in some of these mountain zones reduces the devel- opment of shrub vegetation, potentially influenc- ing the abundance of some prey and their vulner- ability to capture by raptors (Kochert et al. 1988, Thirgood et al. 2002). The maintenance of tradi- tional agricultural practices such as extensive graz- ing, and heterogeneous cultivation, are key to the maintenance of the fauna in some European hab- itats (Tucker and Evans 1997). June 2004 Habitat Use in Harriers 139 Table 5. Logistic regression models for the probability of finding Montagu’s Harrier, Hen Harrier and both species simultaneously in the Site of Community Importance Baixa-Limia. B SE Wald P Hen Harrier Intercept -2.812 0.888 Min. altitude 0.003 0.001 6.749 0.009 Montagu’s Harrier Intercept -2.818 1.054 Scrub-pasture area 4.96 X 10-^ 0.000 4.174 0.041 Min. altitude 0.003 0.001 7.391 0.007 Both species simultaneously Intercept -3.359 0.981 Min. altitude 0.003 0.001 7.264 0.007 The most significant threats for the mountain- ous habitats observed in the study area are the pro- liferation of roads and the massive afforestation of zones of scrub-pasture land. These changes result in the progressive destruction of suitable hunting and nesting habitats for harriers and other species of raptors adapted to open habitats (Tucker and Evans 1997, Petty 1998, Madders 2000). To con- serve harriers effectively, we recommend restric- tions on the proliferation of roads and managing to improve scrubland habitats. Acknowledgments This study was financed with funds from the Consel- leria de Medio Ambiente and the project PGIDT99 PXI20002B (Xunta de Galicia) . 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CURRENT STATUS OF THE OSPREY IN THE CAPE VERDE ISLANDS Luis Palma^ and Joao Ferreira CCMAR, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal Rogerio Gangarato Centro de Estudos de Avifauna Iberica, Rua do Raimundo 119, Apart. 535, 7000-506 Evora, Portugal Pedro Vaz Pinto Centro de Estudos e Investigafdo Cientifica, Universidade Catolica de Angola, R. Nossa Senhora da Maxima n° 29, C.P 2054, Luanda, Angola Abstract. — In 1998 and 1999, we carried out a systematic survey of the Osprey {Pandion haliaetus) in the Cape Verde Islands, to evaluate its population and conservation status. Some poorly surveyed areas were revisited in the summer of 2001 to complete our status assessment. We found an estimated 72-81 pairs on the archipelago, of which 94% were concentrated in the northern Barlavento (windward) islands group. In this area the species is common and seems to be recovering from a presumed decline, probably caused by a long-term overharvesting of eggs and nestlings by humans during past decades. On the contrary, in the southern Sotavento (leeward) islands the species is currently scarce, seemingly still on the decline and already extirpated in the southwesternmost islands. The high percentage of abandoned near-shore nests in the eastern “flat” islands is probably associated with the increasing tourism activities. Key Words: Osprey; Pandion haliaetus; Cape Verde Islands; survey; status. ESTADO actual del AGUILA PESCADORA PANDION HALIAETUS EN LAS ISLAS DE CABO VERDE Resumen. — Durante el aho 1998 y la primavera de 1999 se hizo una prospeccion sistematica del aguila pescadora {Pandion haliaetus) en las islas de Cabo Verde con la intencion de actualizar la informacion sobre su estado poblacional y de conservacion. Algunas areas peor prospectadas fueran visitadas en el verano de 2001 para confirmar datos anteriores. Se obtuvo como estimacion mas probable el numero de 72-81 parejas reproductoras en todo el archipielago, largamente (94%) concentradas en el grupo de islas septentrionales del Barlavento. En este area, la especie es bastante comun y parece estar recu- perandose de un presunto declive durante las decadas pasadas, como resultado probable de un continuo expolio de huevos y polios para la alimentacion humana. A1 contrario, en las islas del grupo sureho del Sotavento, la especie es actualmente muy escasa y sigue aparentemente en declive y incluso ya extinguida en las islas del extreme suroccidental. El incremento del turismo costero constituye una araenaza adi- cional para los nucleus poblacionales de las islas “lianas” orientales al echar la especie de sus sitios vulnerables de nidificacion costera, como lo indica el alto porcentaje de nidos abandonados a lo largo del litoral. [Traduccion de los autores] The breeding distribution of the Osprey {Pan- dion haliaetus) in the Western Palearctic is patchy. Northern populations, especially those of Fenno- scandia and Russia, are large and secure, while those of the south, in the Mediterranean region and Macaronesia, are relict and endangered (Sau- ^ E-mail address: lpalma@ualg.pt rola 1997, Schmidt 1998). Formerly, the species bred in all Macaronesian islands, except for the Azores. In the Canary Islands the Osprey has un- dergone a marked decline (Gonzalez et al. 1992), whereas in the Madeira Islands it was extirpated long ago (Palma 2001). Yet, several toponymic ref- erences remain along sea cliffs as evidence of the Osprey’s occurrence in the past. In the Cape Verde Islands, the Osprey was prob- 141 142 Palma et al. VoL. 38, No. 2 Santo Antao 18 - 23 . S§o Vicente 8 Santa Luzia V, 5^ Branco 1-2 Raso 4-5 14 ^ ^5?ii Sdo Nicolau 17 Rombos F090 Boavista Santiago Maio ’D 40 eokm Figure 1. Geographic location of the Cape Verde Islands and distribution of Osprey breeding territories: confirmed (black squares), probable (gray squares), possible (open squares), and deserted (open triangles). Figures indicate the estimated number of pairs per island. ably common during the 19th century and the first half of the 20th century, as suggested by the scanty and imprecise references available (e.g., Alexander 1898, Murphy 1924, Bourne 1955). Naurois (1987) estimated the population during the 1960s at 45- 70 pairs, plus one possible extra pair in the islets of Rombos, based on an old nest observed. How- ever, these figures resulted from general ornitho- logical observations, and not from a species-target- ed census. Also from incidental observations, Hazevoet (1995) estimated about 50 pairs for the period 1988-93. More recently, R. Dennis and S. Hille (pers. comm.) estimated the slightiy higher number of 55-65 pairs, extrapolated from the pairs and occupied nests observed in 1996-97. Here, we present the results of an Osprey survey carried out in the Gape Verde Islands in 1998-99, with further surveys of some poorly covered areas in June-July 2001. We assessed the current popu- lation and conservation status to provide up-to- date data for the species’ conservation. Prelimi- nary results from this survey were presented by Ferreira and Palma (2000). Study Area and Methods The Cape Verde archipelago (4026 km^; 1047 km coastline perimeter) is made up of 10 islands and six larger islets, about 500 km off continental west Africa be- tween 14°48'-17°12'N and 22°44'-25°22'W (Fig. 1). With the exception of Santa Luzia and the islets, all the islands are inhabited. The islands’ physiography varies widely, ranging from the highly rugged Santo Antao, Sao Nicolau, Santiago, Fogo, and Brava to the relatively flat Sal, Boavista, and Meiio. The coast of the mountainous islands is steep with high rocky cliffs and sea stacks interspersed by smeill to medium-sized pocket beaches, whereas in the low islands the littoral zone is predominantly bordered by extensive sandy beaches and low near-shore islets. Preliminary Data Collecting. Prior to fieldwork, we gathered all available data on the species in Cape Verde from the literature, mapped toponymy as well as unpubl. data from various observers, mainly C. Hazevoet and S. June 2004 Ospreys in the Cape Verde Islands 143 Table 1. Osprey survey effort, and checking of toponymies, literature references, and pers. comm, indicating Osprey locations in the Cape Verde Islands (1998-2001). Islands Altitude"^ Survey Effort^ Toponymies Referenc;es Verified Unverified Verified Unverified Santo Antao 1979 0.326 (44) 2 1 5 0 Sao Vicente 774 0.315 (29) 5 1 8 0 Santa Luzia*^ 395 — 0 0 0 2 Branco‘S 327 — 0 0 1 1 Raso 164 0.210 (2) 0 0 4 0 Sao Nicolau 1304 0.103 (14) 4 0 4 0 Sal 406 0.124 (11) 1 0 7 0 Boavista 390 0.183 (22) 5 0 15 0 Maio 436 0.075 (6) 0 0 4 0 Santiago 1392 0.174 (35) 1 1 8 0 Fogo 2829 0.131 (11) 6 0 4 0 Brava 976 0.217 (9) 0 0 1 0 Rombos*^ 96 — 0 0 0 2 Total (183) 24 3 61 5 ^ Maximum altitude in meters. No. man-d (in brackets) /km of coastline. No systematic survey carried out by the authors. Hille (pers. comm.). We considered toponymy valuable information because the common name of the Osprey in both Portuguese and Capeverdean Creole (“guin- cho”) can be considered a reliable reference to tradi- tional Osprey nest sites. Such toponymies are common m current and presumed former breeding areas along the coasts of southwestern Portugal, the Madeira archi- pelago, the Canaries, and the Cape Verdes. Examples from the latter are “Tope do Guincho” (Top of the Os- prey), “Ponta Ninho do Guincho” (Point of the Osprey Nest), and “Ninho do Guincho” (Osprey Nest), among 27 sites (Table 1) that were checked for their current occupancy status. Field Surveys. We carried out a comprehensive field survey, searching for territorial pairs and nest sites from December 1997— April 1999 throughout the archipelago, with the exception of Santa Luzia and the Islets of Branco and Rombos. Fieldwork was designed to encompass the Osprey extended breeding season in the islands that be- gins in late November (Naurois 1987, Hazevoet 1995). We conducted an overall search in 1998. The following yr, we followed this effort with more intensive searches in the rugged islands of Santo Antao and Sao Nicolau, and checking of previously detected territories in Sao Vi- cente, Sal, Boavista, Maio and Santiago. From May— Sep- tember 2001, we further verified some unconfirmed sites m Santo Antao. We looked for birds and nests systematically, trying to cover the whole of both the coast and the hinterland of the islands, whether or not there were historic sites. Pri- marily, the search was done by motorcycle, car, and foot with binoculars and telescope, either along roads, tracks and footpaths or from lookouts. Whenever needed and feasible, the coasts were also viewed by boat from the sea. Regularly, we interviewed local residents in rural and fishing communities to collect information on the loca- tion of current and old nest sites, and areas where the species was observed commonly in the recent past. In- formation was complemented by that of other observers in the cases of Branco (March 1999; T. Clarke pers comm.), and Santa Luzia and Rombos (October 1999 and February 2001, respectively; P.L. Suarez pers comm.). Birds and nests found were mapped on 1:25 000 to- pographic maps of the Republic of Cape Verde published by the Portuguese Army Geographical Institute. Breeding territories were mapped on an ArcView GIS (Environ- mental Systems Research Institute, Inc., Redlands, CA, U.S.A) simplified overlay (Fig. 1) of the 1:500 000 digital map of the Cape Verde Islands of the Portuguese Army Geographical Institute. Each territory was plotted by the geographic coordinates of the center of the correspon- dent 2X2 km UTM square, read from the 1:25000 to- pographical maps. Survey Effort. We calculated an index of the relative survey effort on each island, relating the number of man- d of fieldwork per island with its perimeter, measured with a curvimeter on the 1:25 000 topographic maps (No. man-d/km of coastline). Santa Luzia, Branco, and Rom- bos were not included in these estimates because infor- mation was mainly based on incidental data collected by other observers. Population Status and Trends. We classified Osprey breeding territories as confirmed, probable, or possible, ac- cording to birds’ observed behavior, frequency and type of sightings at a given location (foraging activities were discarded), and nest occupancy. Confirmed — adults or young on nest, pairs seen (>3 times) within a restricted area, solitary adults seen (>3 times) close to unoccupied nests or where information collected strongly supports 144 Palma et al. VoL. 38, No. 2 Table 2. No. of individual sightings, nests observed, and nest occupancy status of the Osprey in the Cape Verde Islands (1998-2001). Islands Osprey Sightings Nests Verified Percent Nests Occupied Percent Nests Unoccupied Percent Nests Abandoned Santo Antao 78 16 56 38 6 Sao Vicente 70 12 58 42 0 Santa Luzia — 5^ — — — Branco — 0 — — — Raso 12 7 71 29 0 Sao Nicolau 63 10 60 10 30 Sal 14 lO*’ 40 20 40 Boavista 75 25*^ 32 32 36 Maio 3 1 0 0 100 Santiago 7 4 50 50 0 Fogo 0 3 0 0 100 Brava 0 0 0 0 0 Rombos 0 — — — — Total 324 93*= 47 29 24 M. Semedo and P. L. Suarez (pers. comm.)- ’’ Includes nests reported by Barone and Delgado (1998; see text). Occupancy totals calculated from 88 nests (i.e., excluding Santa Luzia). breeding. Probable — pairs seen (<3 times) where infor- mation supports breeding, a pair and solitary adults ob- served on different occasions within a restricted area, sol- itary adults seen twice close to unoccupied nests, or solitary adults observed 2—3 times where information sup- ports breeding. Possible — a pair seen displaying, a pair and a solitary adult observed on different occasions with- in a restricted area, solitary adults seen once near an un- occupied nest, or areas with no adults or nests seen but with supporting information suggesting breeding. To categorize each nest as occupied (with eggs or young, or at least attended [i.e., repaired and ornamented], un- occupied (i.e., presently unattended, but still well pre- served), or abandoned (decaying) we spent only the time needed to view its contents and condition, and to assess presence or absence of birds. We assumed that unoccu- pied nests were either (1) alternate nests, thus one oc- cupied nest should exist within the territory, or (2) tem- porarily not occupied, i.e., observed out of the breeding season or not occupied due to breeding failure during the study period. In evaluating trends, we calculated a minimum change in number of nests per island, comparing the mean val- ues of two estimates (Naurois 1987 and this study). The difference found is presented as a percentage of the mean value of Naurois’s estimate. Results Survey Effort and Land Coverage. During 183 man-days of fieldwork, about 94% of 988-km (the total coastal perimeter of the archipelago, exclud- ing Santa Luzia, Branco, and the Rombos) was sur- veyed. In general, survey effort was higher in is- lands of rougher ground (e.g., Santo Antao; Table 1) to compensate for the lower conspicuousness of birds and nests. Sao Nicolau and Fogo were excep- tions due to the relatively high accessibility of the coastal belt. Santiago, despite over 30 man-d of sur- vey, remained at a comparatively low effort rate due to the large size of the island (Table 1). We checked 89% of all toponymies and 92% of histor- ical references for the presence of Ospreys. Birds and Nests Observed, and Nest Occupancy. Our surveys yielded 324 sightings of Ospreys (Ta- ble 2) and 83 nests. Four additional nests were re- ported from Boavista and one from Sal during the study period (Barone and Delgado 1998, Barone et al. 1999). Furthermore, in Santa Luzia, two nests were found incidentally by J.M. Semedo (pers. comm.) in 1998 and three others by the “Cabo Verde Natura 2000“ team in 1999 (P.L. Suarez pers. comm.). Altogether, we recorded 93 nests during the study period (Table 2). In calculating percent occupancy, we did not consider nests reported from Santa Luzia due to lack of details. Of the remaining 88 nests, 41 (47%) were occupied, 26 (29%) unoccupied, and 21 (24%) abandoned. Except in Fogo, abandoned nests were mainly located on the eastern “flat” is- lands (Sal, Boavista, and Maio), and on Sao Nico- lau (Table 2) . In Fogo, only abandoned nests were June 2004 OSPREVS IN THE CAPE VERDE ISLANDS 145 Table 3. Present and former (1960s; Naurois 1987) Osprey population estimates, densities, and recent population trends in the Cape Verde Islands. Islands 1998-2001 Estimate^ Densit’V Naurois ’ s Estimate Percent Change Santo Antao 18-23 0.15 8-1 h + 115.8 Sao Vicente 8 0.09 3-6 + 77.8 Santa Luzia^ 5-6 0.17 3-4 — Branco^ 1-2 0.18 3-4 — Raso 4-5 0.47 1-2 +200 Sao Nicolau 17 0.13 5-8^ + 161.5 Sal 4 0.04 6-8 -42.9 Boavista 11 0.09 5-8 + 69.2 Maio 1 0.01 2-3 -60 Santiago 3-4 0.02 4-6" -30 Fogo 0 2-5" -100 Brava 0 3-5 -100 Rombos 0 1? -100 Total 72-81 0.13 46-71 +31" No. of estimated territories/pairs; lower estimates include confirmed and probable territories. Mean No. estimated pairs/km of coastline. Crude estimates according to Naurois (1987), hence corresponding percent change is unreliable. Percent change not calculated due to the unreliability of current estimates. ® Overall percent change calculated from totals excluding Santa Luzia and Rombos. recorded, and in Brava no nests or birds were found. In the Rombos, RL. Suarez (pers. comm.) also did not find any evidence of Osprey use in 2001. Nests were built on the top of pinnacles (18%), on isolated sea rocks (14%), on rock ledges on steep slopes (14%), on hilltop peaks and crests (12%), on sea-cliff ledges and fallen blocks (10%), on protruding rock platforms on gentle slopes (21%), on level ground by the shore (5%), and on flat near-shore islets (1%). The first five types of nest sites predominate on mountainous islands, while the others are typical of the flatter islands. We also found a few nests atop masts of stranded vessels (5%). Nesting on the crown of palms {Phoe- nix atlantidis) (Hazevoet 1995, Ontiveros 2003) and on the sand (S. Hille pers. comm.) has also been reported from Boavista. This high plasticity in the choice of nestsites, comparable to that found by Bretagnolle et al. (2001) in New Caledonia, had already been described by Naurois (1987). Distribution, Population Estimates, and Trends. We initially estimated the Osprey population at 54- 81 pairs within the area surveyed (54 confirmed, 18 probable, and 9 possible). However, we consid- ered the lower value (confirmed pairs) too conser- vative as both the comparison between 1998 and 1999 censuses in Sal and Boavista, and the check- ing of unconfirmed sites at Santo Antao in 2001, indicated that most of the probable pairs would likely be confirmed with enough fieldwork. There- fore, we believed that adding both confirmed and probable pairs would offer the more realistic esti- mate of 72-81 pairs in 1998-99 (Table 3). The pre- liminary figure of 5—6 pairs in Santa Luzia is based on data provided by P.L. Suarez (pers. comm.). The highest numbers of Osprey pairs are in San- to Antao, Sao Nicolau, and Boavista, which account for 37% of the coastline and 63-64% of the Osprey population. The majority, 94% of Osprey pairs are concentrated in the Barlavento (“windward”) group (Santo Antao o Boavista; 60% of the coast- line), in contrast with only 6% of the population in the Sotavento (“leeward”) group (Maio Bra- va; 40% of the coastline; Table 3, Fig. 1). Mean linear densities (Table 3) are much higher in the Barlavento (0.16 pairs/km of coastline) than in the Sotavento (0.01 pairs/km) . Density is espe- cially high in the small islet of Raso (0.47 pairs/ km) . The comparison between the present estimate and Naurois (1987) suggested that during the last three decades, upward trends occurred in Santo Antao, Raso, and Sao Nicolau, and moderate pos- itive changes in Sao Vicente and Boavista, all in the Barlavento (Table 3) . However, the figures for San- 146 Palma et al. VoL. 38, No. 2 to Antao and Sao Nicolau should be taken with caution because Naurois’s estimates were not made systematically. The trends were negative in Sal, Maio, Santiago, Togo, Brava, and Rombos, which, apart from Sal, are all in the Sotavento. At the last three islands there was no evidence of Osprey presence. In San- tiago the percent of change must also be viewed with caution because of the uncertainty of Naurois’ estimate. The overall trend in the archipelago is positive. Discussion Nest Occupancy. The interpretation of present nest occupancy during a short-term study is limited by the fact that these estimates are not indepen- dent of the number of extant alternate nests. Such alternate nests are common all over the archipel- ago, especially in islands of milder topography, probably as a way to avoid natural and human pre- dation or disturbance. In Boavista, where human interference and predation by Brown-necked ra- vens (Corvus rufficollis) are presumably high, P.L. Suarez (pers. comm.) has recorded that nests out- number pairs by 3-4 times. Although the variety of nesting situations suggests that breeding habitat is not a limiting factor in the species distribution in general, the vulnerability of many nest sites in the eastern islands is probably impairing reproduction. The percent occupancy of nests (Table 2) is clearly lower at islands such as Sal, Boavista, and Maio, where potential disturbance is higher. In Boavista, low occupancy rates have also been re- ported by other observers (Ontiveros 2003, P.L. Suarez pers. comm.). A tendency to desert near- shore nests seems evident at this island and may eventually cause the disappearance of pairs occu- pying areas of level or slightly broken terrain (On- tiveros 2003). In Sao Nicolau, despite its steep-in- land mountains, the number of abandoned nests was also high probably due to their vulnerable lo- cations by the shore. In New Caledonia, Bretag- nolle et al. (2001) also reported a tendency of Ospreys to desert nests exposed to human distur- bance, especially those on the ground. High nest vulnerability may explain the Osprey decline in Sal and Maio. Conversely, in mountainous islands such as San- to Antao, Sao Vicente, and Santiago, less accessible nests predominate, as well as low percentages of abandoned nests. However, all nests found in Togo were abandoned, despite being located in inacces- sible places, so disturbance is unlikely to be the cause of desertion at the island. Population Status and Trends. Apart from Santo Antao and Sao Nicolau, Naurois (1987) considered the Barlavento well surveyed. In Sao Nicolau, how- ever, birds and nests are relatively conspicuous, so the numbers he reported were probably fairly ac- curate. Therefore, we believe, with the exception of Sal, that a genuine population increase has oc- curred for the Barlavento since Naurois’ time. The population recovery in the Barlavento likely resulted from a decreasing intensity of the collect- ing of eggs and nestlings reported by Naurois (1964) . This was corroborated by statements of res- idents during our study and seems particularly ob- vious in Sao Vicente, where the present situation contrasts with what Naurois formerly described as near extirpation of Osprey due to overharvesting. Opposite of the pattern observed in the Barlav- ento, a depression in numbers was still evident in all islands of the Sotavento, where the Osprey has apparently always been less abundant. Naurois (1987) suggested that variation in prey availability may explain the differences in Osprey numbers us- ing these two groups of islands. The Osprey pop- ulation seems to be most depressed further to the southwest (Table 3). In particular, the decaying state of the nests found in Togo and the lack of any trace of Osprey presence in Brava and Rombos suggest that the species has been extirpated from these islands as a breeder. Acknowledgments We are deeply indebted to Cornells Hazevoet, Sabine Hille, Phil Hansbro, Tony Clarke, Jose Maria Semedo, and Pedro Lopez Suarez for the valuable unpubl. data provided. We thank Anibal Medina and Ederio Almada in the Instituto Nacional de Desenvolvimento das Pescas (INDP) of Cape Verde for their continuous support. We also thank Pedro Beja, Cornells Hazevoet, Sabine Hille, Ian Warkentin, Mark Martell, and an anonymous referee for their critical review of the manuscript; Carla Janeiro for drawing the map; and others that helped us in various ways. We owe a final word of thanks to the prompt and genuine “morabeza” of the people of the Cape Verde Islands. This study was funded by the Sudoeste Alente- jano e Costa Vicentina Natural Park and the Instituto Portugues da Juventude (Lusiadas programme) of Por- tugal, and the FAO-“Fisheries Development” programme of Cape Verde, Literature Cited Alexander, B. 1898. An ornithological expedition to the Cape Verde Islands. Ibis 4:74-118. Barone, R. and G. Delgado. 1998. Observaciones orni- tologicas en el archipielago de Cabo Verde, Septiem- June 2004 Ospreys in the Cape Verde Islands 147 bre-Octubre de 1998. II. Aves nidificantes. Rev. Acad. Canar. Cienc. 10:41-64. , M.F. DEL Castillo, and JJ- Bacallado. 1999. Nueva contribucion a la ornitologia de Cabo Verde. Observaciones de interes en las islas de Barlovento, Abril de 1999. Rev. Acad. Canar. Cienc. 9:173-187. Bourne, W.R.P. 1955. The birds of the Cape Verde Is- lands. Ibis 97:508-556. Bretagnolle, V, M. Pandolfi, V. Lecoq, and J. Broud- issou. 2001. Le balbuzard pecheur Pandion haliaetus en Nouvelle-Caledonie: effectif, repartition et men- aces. Alauda 69:491-501. Ferreira, J. and L. Palma. 2000. The Osprey {Pandion haliaetus) in the Cape Verde Islands: distribution, pop- ulation trends and conservation problems. Pages 721- 727 in R.D. Chancellor and B.-U. Meyburg [Eds.], Raptors at Risk. World Working Group on Birds of Prey and Owls/Hancock House, Berlin, Germany. Gonzalez, G., J.M. Santiago, and L. Fernandez. 1992. El aguila pescadora {Pandion haliaetus) en Espaha. Censo, reproduccion y conservacion. Coleccion Tec- nica. ICONA, Madrid, Spain. Hazevoet, C.J. 1995. The birds of the Cape Verde Is- lands. British Ornithologists’ Union Check-list 13. British Ornithologists’ Union, Tring, Hertfordshire, U.K. Murphy, R.C. 1924. The marine ornithology of the Cape Verde Islands, with a list of the birds of all the archi- pelago. Bull. Amer. Mus. Nat. Hist. 50:211-278. Naurois, R. 1964. Les oiseaux des iles du Cap-Vert. Sug- gestions en vue de leur sauvegarde. Garcia de Orta, IICT, Lisboa 12:609-620. . 1987. Le Balbuzard {Pandion haliaetusC.) aux iles du Cap Vert. Ann. Mus. Civ. Stor. Nat. Genova 86:657— 682. Ontiveros, D. 2003. Nesting distribution, food habits, and conservation of Osprey on Boavista Island (Ar- chipelago of Cape Verde)./. Raptor Res. 37:67-70 Palma, L. 2001. The Osprey {Pandion haliaetus) on the Portuguese coast: past, present and recovery poten- tial. Vbgelwelt 122:179—190. Saurola, P. 1997. The Osprey {Pandion haliaetus) and modern forestry: a review of population trends and their causes in Europe./. Raptor Res. 31:129-137. Schmidt, D. 1998. Osprey {Pandion haliaetus) breeding numbers in the western Palearctic. Pages 323-326 m R.D. Chancellor, B.-U. Meyburg, and J.J. Eerrero [Eds.] , Holarctic birds of prey. World Working Group on Birds of Prey and Owls and Asociacion para la De- fensa de la Naturaleza y los Recursos de Extremadura, Merida, Spain. Received 13 June 2003; accepted 19 January 2004 Associate Editor: Ian G. Warkentin Short Communications J Raptor Res. 38 (2): 148-1 52 © 2004 The Raptor Research Foundation, Inc. Development of Hunting Behavior in Hacked Aplomado Falcons Jessi L. Brown/ William R. Heinrich, J. Peter Jenny, and Brian D. Mutch The Peregrine Fund, 5668 W. Flying Hawk Lane, Boise, ID 83709 U.S.A. Key Words: Aplomado Falcon-, Falco femoralis; cooperative hunting, foraging behavior, hacking, Texas-, hunting behavior. The extent to which hunting is instinctive in young raptors as proposed by Brown and Amadon (1968) is dif- hcult to investigate in wild populations. Parents of many species entice fledglings by carrying prey items, release or flush live prey in the vicinity of fledglings, and accom- pany them on hunting forays (Newton 1979, Schaadt and Rymon 1982, Sherrod 1983). However, numerous resto- ration projects involving the release (“hack”) of young raptors into the wild, as developed centuries ago by fal- coners, have shown that hunting prohciency readily de- velops in the absence of parents (Sherrod 1983, Mutch et al. 2000). Moreover, hacked raptors may develop at rates similar to their wild counterparts; for example, hacked Peregrine Falcons {Falco peregrinus) and Red- necked Falcons {Falco chicquera) fledged and began kill- ing prey at ages comparable to those in wild populations (Sherrod 1983, Bednarek 1993). The “hacking” proce- dure therefore facilitates the study of innate components involved in the ontogeny of hunting behavior. The northern Aplomado Falcon {Falco femoralis septen- tnonalis) is particularly suited to such investigations as it IS naturally tolerant of human presence and easily ob- served in its open savanna habitat, where it typically hunts from isolated perches. Of further interest is that adult pairs hunt cooperatively for avian prey, a mode that Hector (1986) believed an inherent tendency as based on his observations of breeding adults in eastern Mexico. In this report, we summarize our records and those of numerous observers who attended the development of hacked Aplomado Falcons released by The Peregrine Fund in Texas since 1993. Herein, we describe the de- velopment of their hunting behavior in the absence of parental influence. Methods Study Area. Falcons were released in Texas {N = 25 release sites) at three focal areas: the lower Rio Grande valley in the vicinity of Laguna Atascosa National Wildlife Refuge (NWR); the coastal bend of southeastern Texas, ^ E-mail address: jbrown@peregrinefund.org including Aransas NWR and Matagorda Island NWR; and western Texas in Jeff Davis County. Vegetation at sites included savanna, coastal prairie, and Chihuahuan grass- land/ desertscrub (see McAlister and McAlister 1995, Perez et al. 1996, Powell 2000). Methods. Procedures for the release of Aplomado Fal- cons were modified from those developed for Peregrine Falcons (Sherrod et al. 1987, Mutch et al. 2000). Follow- ing a pilot study in 1986-89, large-scale releases of Aplo- mado Falcons began in 1993 and continued through 2002, with 354 female falcons and 443 male falcons re- leased during that period. At about 30 d of age, young falcons were transported to release sites in Texas; these featured 3-5 m tall towers, each topped with a release box facing away from an observation blind. Release groups of 2-8 falcons were placed within similar-aged co- horts regardless of gender. While still in release boxes, the falcons were fed and monitored by attendants. Boxes were opened when falcons were 38-41 d old, and the attendants continued to provide food and monitor the site daily for 6 wk following release. All falcons were banded with Geological Survey bands and anodized alu- minum color bands with 1-2 alphanumeric characters, allowing attendants to identify individuals from a dis- tance. Falcons were continuously observed during day- light hours for the hrst 3 d following a release, and then during morning and evening hours only (dawn to 1100 H and 1500 H to dusk). Following the close of a release site, attendants provided reports summarizing the releas- es, dispersal, hunting behaviors, and unusual events ob- served at that site. We extracted data from 46 project reports from 1993- 2002 representing 22 release sites. Hunts were classihed to mode as either solitary or group, with all hunts in- volving two or more falcons termed “group hunts,” re- gardless of notes suggesting the hunts could he consid- ered group, pseudocooperative, or cooperative (Ellis et al. 1993). Kills were recorded when a hunt ended suc- cessfully, or circumstantially determined when a falcon was seen with prey other than that supplied at the hack tower. We recorded 305 separate hunts, including 30 pu- tative (circumstantial) kills, or 6.6 (95% Conhdence In- terval = ±1.8, range 1-26) per site/yr. Statistical Analyses. We pooled data from west and south Texas, as separate analyses showed similar mean values and widely overlapping 95% conhdence intervals (for age at hrst pursuit; female in south Texas, N = 65, X age = 63.9 d, 95% Cl = ±3.1; female in west Texas, N = 11, X age = 65.7 d, 95% Cl = ±7.9; males in south 148 June 2004 Short Communications 149 Table 1. Comparison by gender of first vertebrate pursuits and vertebrate kills in hacked Aplomado Falcons. Values are means in days (95% confidence intervals). Female Males X N X N First pursuits Age 64.1 (61.4-66.9) 76 59.1 (56.2-62.0) 78 Days since release 24.3 (21.5-27.0) 76 18.5 (15.5-21.4) 78 First kills Age 73.1 (67.1-79.0) 19 74.8 (69.3-80.4) 19 Days since release 32.4 (26.5-38.4) 19 34.8 (29.4-40.2) 19 Texas, N = 69, x age = 58.1 d, 95% Cl = ±2.8; males in west Texas, N = 9, x age = 66.8 d, 95% Cl = ±14.3). Our assumption that the behavior of each falcon was in- dependent of its release cohort was supported by i^tests which showed that inter-cohort behavior was as variable as intra-cohort behavior (for age at first vertebrate pur- suit; females, F = 0.81, df = 52, P = 0.22; males, F = 0.91, df = 47, P = 0.37). We compared differences be- tween behaviors exhibited by male and female Aplomado Falcons, age differences at first solitary and first group pursuit of vertebrate prey by each individual, and tem- poral distribution and relative success of hunting modes. Data are expressed as means and 95% confidence inter- vals (95% Cl) unless otherwise stated. Results and Discussion Pursuit and Capture of Invertebrates. All sites reported hacked falcons chasing, capturing, and consuming in- sects from soon after release through the end of the ob- servation periods (42 d after release). Pursuit of insects was so common that many attendants summarized rather than detailed specific hunts. Falcons caught insects in the air, plucked them from branches and grass stems, and pursued them by running on the ground. Groups of fal- cons chased the same insect, and falcons occasionally pi- rated insect prey from each other. At two sites, falcons gathered along the margins of controlled-burn plots and chased insects flushed from cover by the flames. Along the Texas gulf coast, falcons caught and consumed sand fiddler crabs ( Uca panacea) locally abundant on tidal flats and in marshy areas (McAlister and McAlister 1995). Pursuit of Vertebrates. Falcons pursued 67 species of vertebrates as apparent hunting targets, and 34 species during territorial defense or other aggression, the latter easily differentiated by the falcons’ loud “kekking” vo- calization (Keddy-Hector 2000) . Raptors and large mam- mals evoked defensive behavior most frequently, but fal- cons also attempted to drive away an armadillo {Dasypus novemcinctus) and a Texas tortoise (Gopherus berlandieri). All 275 vertebrate hunting attempts were directed to- wards birds, but two mammals and four reptiles were ob- served amongst the putative kills. Falcons typically flew directly from a perch toward prey in trees, on the ground, or flying past. The two largest species pursued with apparent hunting intent were Great Blue Fferon (Ar- dea herodias'. males 2576 g, N = 17; females 2204 g, N = 15) and Roseate Spoonbill {Ajaia ajaja: males 1240-1750 g, females 1400-1700 g; no sample size reported), and the smallest was the Ruby-throated Hummingbird (Ar- chilochus colubris: males 3.0 g, N = 202; females 3.3 g, N = 489). The largest reported kill by the hacked falcons was a Mourning Dove (Zenaida macroura: males 123 g, V = 140; females 115 g, N = 95; Dunning 1993). Sex Differences. Attendants recorded the first known vertebrate hunts for 154 individual falcons. Males pur- sued vertebrates earlier than females, measured both in age and d since release (Table 1). Kills were witnessed in 35 first successful vertebrate hunts, and an additional 30 putative kills were determined circumstantially. Of 38 first kills by known falcons, 19 were by females and 19 by males. Ages and d since release were similar for these falcons (Table 1). Our data on the onset of vertebrate pursuit behavior agree with other studies of falcon development: the sexes of hacked Aplomado Falcons developed at different rates. Sherrod (1983) found that hacked male Peregrine Falcons began their first pursuits of vertebrates at an ear- lier age than females (50.6 d versus 55.7 d, A = 43 and 41, respectively). However, if we assume that the putative kill component represented prey killed by the possessor, male and female Aplomado Falcons appeared to kill ver- tebrate prey at the same age (Table 1). More putative kills were ascribed to females than males (15 to females, 7 to males) . Although this could represent piracy by larg- er females upon smaller males, observations suggest that the tendency is rare (2 successful piracies and 5 piracy attempts in 275 hunts). In any case, once Aplomado Falcons began pursuing vertebrate prey, females progressed to prey acquisition more quickly than males. On average, females obtained prey about 10 d after the onset of pursuit behavior, com- pared to males at 15 d. Bednarek (1993) also reported first kills at ca. the same age for each sex of hacked Red- necked Falcons; 60 and 68 d for males (N = 2) and 63 150 Short Communications VoL. 38, No. 2 60 n 174-193 194-213 214-233 234-253 254-273 Julian Date (1 January = 1) ■ Solitary H Group Figure 1. Incidence of solitary and group hunting by hacked Aplomado Falcons in Texas. Y-axis values are numbers of solitary and group hunts observed within 20- d intervals corresponding to first and last hunts observed (23 June-28 September 1993-2002). and 69 d for females {N = 2) . These results run counter to the often-held assumption that female raptors lag be- hind males in post-fledging development. Sherrod (1983) reported only a slight difference in the mean age of kills for peregrines (73.3 d for males and 76.8 d for females, N = 62 and 33, respectively) . Group Hunting. Of 275 pursuits of vertebrates report- ed as hunts, 125 involved more than one falcon (range 2-12 falcons) simultaneously chasing the same prey. Cen- soring hunts with group size reported merely as “group” {N = 9), 399 falcons participated in group hunts or 3.4 (95% Cl = ±0.3) participants per hunt. Of hunts with known outcomes, 20 of 122 (16%) group hunts were suc- cessful, whereas 15 of 150 (10%) solitary hunts succeed- ed As the hacking periods progressed, group hunts were observed more often, and fewer solitary hunts were seen (Fig. 1). For the 23 falcons confirmed hunting both alone and in groups, there was no difference between the ages at first pursuit for either hunting mode (solitary = 59.4 d, 95% Cl = ±5.3; group = 60.3 d, 95% Cl = ±57). The increase in group hunts may therefore relate to factors other than the age of participants. It is quite possible that the prey base composition changed through the yr, with proportionally more recently-fledged, vulner- able passerines present in late summer. Moreover, the number of falcons per hack site increased throughout the season; at most sites, cohorts of falcons released se- quentially throughout the hack season accumulated to a maximum of six cohorts per site, potentially presenting greater opportunities to participate in group hunts. Group hunting commonly occurred at all hack sites. Although many group hunts were doubtless the conse- quence of several falcons coincidentally pursuing the same prey, detailed reports of group hunts suggested that some contained elements of cooperation. Ellis et al. (1993) suggested that true cooperative hunts, as de- scribed for mated pairs, family groups, and sibling groups, would have certain characteristics. These includ- ed coordinated movements, sometimes with some mem- bers performing rushing attacks having a low probability of capture success in order to increase the group’s chance of capture; social signals such as vocalizations to initiate or coordinate the hunt; and orderly prey sharing. Observations of the hacked falcons were sometimes con- sistent with these criteria (Appendix, observations 1-3) . Group hunting was not limited to cohorts of hacked falcon nest mates. Hack sites were regularly visited by fal- cons released at other sites, especially those closely spaced within Laguna Atascosa and Matagorda Island NWRs. These visitors were accepted with little hesitation by the local falcons, and would feed from the same tower and join in group hunts. In later years, juvenile falcons dispersing from wild nests, always a month or more older than the hacked falcons, appeared at hack sites, and were similarly tolerated (Appendix, observation 4) . Territorial adult falcons, whether previously hacked or wild-pro- duced, displayed aggression toward hacked falcons, but other adults interacted benignly with the juveniles (Ap- pendix, observation 5). Hector (1986) found that adult Aplomado Falcons were significantly more successful when hunting birds as pairs than when alone: 45% of pair attacks were success- ful versus 21% of solo hunts. Success rates calculated for our data favored group hunts as well (16% versus 10%). Even so, from the standpoint of prey acquisition by in- dividual hacked Aplomado Falcons, group hunts were far less efficient than solitary hunts. For group hunts in which both group size and hunt outcome were known, 386 falcons participated in 113 group hunts of which 20 were successful, leading to a success rate of 5% per par- ticipant, less than one half the frequency of success re- corded for solitary hunts (10%). Because group hunting by recently fledged falcons is likely precursory to the co- operative hunting of adult pairs and because food is not usually shared among juveniles participating in group hunts, adaptive payoffs of this behavior would appear to be delayed a yr or more. Our findings support those of other studies that young raptors quickly acquire foraging skills in the absence of parental influence. However, the young hacked Aplo- mado Falcons behaved differently than Peregrine Fal- cons: groups of hacked peregrines rarely share food and their conspecific interactions are markedly more aggres- sive (B. Mutch pers. comm.). Instead, our data support those of Hector (1986), who theorized that cooperative hunting is innate in Aplomado Falcons. He noted that throughout the species’ range mated pairs hunt together yr-round, both sexes vocalize to instigate participation by their mates in hunting and defense activities, different pairs show the same division of labor in hunts, and nest- lings and fledglings are more passive toward one another than those of other falcon species. The behavior ob- June 2004 Short Communications 151 served among the hacked Aplomado Falcons was similar to that of foraging adult pairs. Young Aplomado Falcons persisted in group hunt participation despite the lack of immediate payoff, which points to future benefits asso- ciated with the early practice of such behavior. Resumen. — Examinamos 275 registros de comportamien- to de caza, incluyendo 125 grupos de caza, entre pollue- los de halcones perdiceros {Falco femoralis) en el sur de Texas. En promedio, los halcones machos comenzaron a perseguir presas vertebradas 5 dias mas temprano que sus hembras “hermanas”, sin embargo ambos sexos ma- taron presas vertebradas a la misma edad. Mientras que los grupos de caza estuvieron mas propensos a ocurrir mas tarde en el aho, los individuos de halcon perdicero no mostraron correlacion entre la edad y la epoca cuan- do ellos participaron en la caceria cooperativa. Mas in- tentos de caza en grupo terminaron exitosamente (16% versus 10%); sin embargo, con una media de 3,4 parti- cipantes por grupo de caza, estos fueron mucho menos eficientes por participante (5% de oportunidades de ex- ito). Algunos grupos de caza mostraron caracteristicas tipicas de cacerias cooperativas exhibidas por las parejas de halcones perdiceros. Nuestras observaciones sugieren que los grupos de caza son innatos en los halcones Per- diceros y que las ineficientes cacerias en grupo de los jovenes halcones pueden ayudar a desarrollar las habili- dades sociales y las tecnicas de caza necesarias para las futuras cacerias cooperativas con sus parejas. [Traduccion de Cesar Marquez] Acknowledgments This study was supported by The Peregrine Fund. We thank J. Belthoff, B. Burnham, M. Curti, H. McElroy, A. Montoya, A. Nicholas, and D. Whitacre for help through- out. We acknowledge the valuable observations and note- taking of countless hack site attendants. Comments by T. Cade, G. Hunt, S. Sherrod, and two anonymous reviewers improved earlier drafts of this manuscript. Literature Cited Bednarek, W. 1993. Controlled hacking, a method of re- search into the biology of non-indigenous raptors: the Red-headed Falcon Falco chicquera chicquera. Pages 207-212 in M.K. Nicholls and R. Clarke [Eds.], Biol- ogy and conservation of small falcons: proceedings of the 1991 Hawk and Owl Trust Conference. The Hawk and Owl Trust, London, U.K. Brown, L.H. and D. Amadon. 1968. Eagles, hawks, and falcons of the world. 2 vols. McGraw-Hill, New York, NY U.S.A. Dunning, J.B. 1993. CRC handbook of avian body masses. CRC Press, Boca Raton, FL U.S.A. Ellis, D.H., J.C. Bednarz, D.G. Smith, and S.P. Flem- ming. 1993. Social foraging classes in raptorial birds. BioScience 43:14-20. Hector, D.P. 1986. Cooperative hunting and its relation- ship to foraging success and prey size in an avian predator. Ethology 73:247-257. Keddy-Hector, D.P. 2000. Aplomado Falcon {Falco femor- alis). In A. Poole and F. Gill [Eds.], The birds of North America, No. 549. The Birds of North America, Inc , Philadelphia, PA U.S.A. McAlister, W.H. and M.K. McAlister. 1995. Aransas- a naturalist’s guide. Univ. Texas Press, Austin, TX U.S.A. Mutch, B.D., J.P. Jenny, W.R. Heinrich, and C.E. Sand- fort. 2000. The Northern Aplomado Falcon: biology, restoration, and hacking procedures. The Peregrine Fund, Inc., Boise, ID U.S.A. Newton, I. 1979. Population ecology of raptors. Buteo Books, Vermillion, SD U.S.A. Perez, C.J., P.J. Zwank, and D.W. Smith. 1996. Survival, movements, and habitat use of Aplomado Falcons re- leased in southern Texas./. Raptor Res. 30:175-182 Powell, A.M. 2000. Grasses of the Trans-Pecos and ad- jacent areas. Iron Mountain Press, Marathon, TX U.S.A. SCHAADT, G.P. AND L.M. Rymon. 1982. Innate fishing be- havior of Ospreys. Raptor Res. 16:61-62. Sherrod, S. 1983. Behavior of fledgling Peregrines. The Peregrine Fund, Inc., Ithaca, NYU.S.A. , W.R. Heinrich, W.A. Burnham, J.H. Barclay, and TJ. Cade. 1987. Hacking: a method for releasing Peregrine Falcons and other birds of prey. The Pere- grine Fund, Inc., Boise, ID U.S.A. Received 12 January 2003; accepted 16 November 2003 Appendix — Selected Observations 1. A group of four falcons (64.8 ± 5.5 d old) chasing a Cliff Swallow {Petrochelidon pyrrhonta) surrounded it such that, as it tried to escape from one pursuing fal- con, it met another in its path. Eventually the swallow sought refuge in a mesquite tree (Prosopis glandulosa) only to be flushed by one falcon as the others waited nearby and resumed the chase. Later, at least 10 fal- cons chased a pair of Loggerhead Shrikes {Lanius lu- dovicianus) in the same manner. The falcons gave short “chipping” vocalizations characteristic of those exhibited by mated pairs during cooperative hunts (Keddy-Hector 2000, Peregrine Fund unpubl. data) Both hunts were unsuccessful, but 8 d later three of the falcons (81 ± 1 d old) from the first hunt, caught a Cliff Swallow after chasing it high in the air. The successful falcon fed on his prey while the other two watched intently but passively. 2. Observers witnessed a successful hunt by five falcons on an Eastern Meadowlark {Sturnella magna). As it tried to escape across the open landscape, three fal- cons tail-chased, while two stooped from above. On the following d, a group of six falcons caught a small bird in the same manner. One month later, groups chased and killed Eastern Kingbirds {Tyrannus tyran- 152 Short Communications VoL. 38, No. 2 nus). During one hunt, eight falcons chased a king- bird for about 1 min until it sought refuge in a mes- quite. The falcons followed it, with five waiting in the treetop while three others ran and hopped through the lower branches until the kingbird flushed and was captured, a sequence often exhibited by mated pairs (Keddy-Hector 2000) . 3. In 1993, a group of seven falcons chased and caught a Ladder-backed Woodpecker {Picoides scalaris). Sev- eral falcons fed on it simultaneously, while the others settled on perches nearby. When a Northern Harrier {Circus cyaneus) approached the kill site, two of the non-feeding falcons left the group and drove the har- rier away while the others continued their meal un- disturbed (C. Perez pers. comm.). 4. A wild hatch-year (HY) male falcon was found eating prey while perched on the rafters underneath one of the hack boxes. Attendants reported that this falcon “generously shared’’ his kill, possibly a swallow, with a female hacked falcon. 5. A wild-hatched adult female arrived at a hack site and led the first successful group hunt of the yr. She cap- tured a meadowlark after chasing it together with two HY hacked falcons, all three stooping in turn. At a different hack site, a previously hacked adult female regularly visited from 1999-2002. This falcon occa- sionally fed from the tower, joined in hunts and tower defense, and tolerated food-begging from the HY fal- cons. Attendants described her behavior as “mentor- ing.” J RaptcrrRes. 38(2) T52-157 © 2004 The Raptor Research Foundation, Inc. Summer Roadside Raptor Surveys in the Western Pampas of Argentina Michael I. Goldstein^ and TobyJ. Hibbitts^ Texas A&M University, Department of Wildlife and Fisheries Sciences, 2258 TAMU, College Station, TX 77843 U.S.A. Key Words: Chimango Caracara\ Milvago chimango; Crest- ed Caracara; Caracara plancus; agriculture, mesquite, Argen- tina] survey. Roadside surveys are useful for assessing habitat pref- erences of diurnal raptors. Although the limitations and biases inherent in roadside counts are well known (Fuller and Mosher 1987), roadside surveys serve as a practical means for rapidly assessing raptor distribution and abun- dance over large areas (Ellis et al. 1990). Roadside sur- veys have been used to compare species richness and abundance between broad regions and to assess impacts of anthropogenic-habitat transformations on raptors. These types of surveys have been carried out in Europe (Meyburg 1973), Africa (Cade 1969), North America (Woffinden and Murphy 1977), Latin America (Ellis et al 1990), Patagonia (Donazar et al. 1993), and a grass- land-agricultural ecosystem in Argentina (Leveau and Leveau 2002). The distribution of raptors across central Argentina was surveyed east to west from Buenos Aires ^ Present address: USDA Forest Service, Chugach Nation- al Forest, 3301 C Street, Suite 300, Anchorage, AK 99503 U.S.A.; e-mail address: mgoldstein@fs.fed. us ^ Present address: School of Animal, Plant and Environ- mental Sciences, University of the Witwatersrand, Private Bag 3, Wits 2050, South Africa. to Zapala, Neuquen (Travaini et al. 1995); we add to this body of knowledge and report results obtained from roadside raptor surveys carried out during December 1998 and January 1999 in the provinces of La Pampa, Cordoba, and San Luis. Study Area and Methods Survey routes extended from Huanchilla, Cordoba in the north and Intendente Alvear, La Pampa in the east to the western border of La Pampa Province, approach- ing the Rio Negro near the city of Neuquen in the prov- ince of Neuquen, Argentina (ca. 35°S, 64°W; Fig. 1). The climate becomes more arid from the eastern coast (Buen- os Aires) to the mountains of western Argentina, with vegetation changing from agricultural grasslands to mes- quite {Prosopis spp.) to desert-scrub grasslands. We chose four primary landscape divisions based on characteristics of the predominant vegetation type: agriculture, mixed agriculture/mesquite, mesquite, and desert-scrub grass- lands. The agriculture category consisted of a mix of cattle ranching and row-crop agriculture, with dominant sum- mer crops of alfalfa, sunflower, sorghum, and corn. In the agricultural region, forests and shrubs exist intermit- tently, generally planted as shade areas for cattle, for wind breaks between fields, and as entrance corridors to estate houses. These forests most frequently consisted of groves of introduced eucalyptus {Eucalyptus spp.) trees. The mixed agriculture/mesquite category contained 25- 75% mesquite, while the mesquite category contained June 2004 Short Communications 153 Figure 1. Map of roadside survey locations in the western pampas and central Argentina. 154 Short Communications VoL. 38, No. 2 Table 1. Number of raptors observed in landscapes surveyed in the western pampas and central Argentina, Decem- ber 1998-January 1999. Species Scientific Names Habitat Types Agriculture Agriculture/ Mesquite Mesquite Desert Scrub Total American Kestrel Falco sparverius 2 10 7 1 20 Aplomado Falcon Falco femoralis 2 0 2 1 5 White-tailed Kite Elanus leucurus 0 1 0 0 1 Chimango Caracara Milvago chimango 292 138 38 22 490 Crested Caracara Caracara plancus 42 48 63 19 172 Swainson’s Hawk Buteo swainsoni 36 1 0 0 37 Red-backed Hawk Buteo polyosoma 1 1 1 3 6 White-tailed Hawk Buteo albicaudatus 0 3 0 3 6 Burrowing Owl Athene cunicularia 12 1 7 0 20 Short-eared Owl Asio flammeus 1 1 0 0 2 Turkey Vulture Cathartes aura 0 0 0 12 12 Black Vulture Coragyps atratus 0 4 0 1 5 Richness 8 10 6 8 Abundance 388 208 118 62 776 Richness/100 km 1.5 2.6 2.8 6.0 Abundance/ 100 km 74.9 54.6 54.6 46.6 >75% mesquite with small grassy patches scattered throughout. The desert-scrub grassland category con- tained <10% tree cover and generally consisted of nat- ural grasslands. We traveled survey routes between 0600-1100 H and 1630-2030 H (local time; on 1 January 1999 sunrise was at 0545 H and sunset at 2010 H) . Surveys were completed on 32 routes over 16 d, with a minimum of 50 km and a maximum of 248 km per route. Each route was surveyed once to ensure bird sightings would be independent. The weather on survey days was partly cloudy to sunny with either no wind or a slight breeze. We recorded each oc- currence of birds of prey and New World vultures in each habitat. We traveled on paved highways at approximately 80-90 km/hr, slightly faster than recommended (Fuller and Mosher 1987), but still at speeds at which we were able to detect species in different habitats, particularly the five common species analyzed for habitat selection. To minimize differences in detectability among sur- veys, we standardized time of d, weather, driving speed, and number of observers (Fuller and Mosher 1987). In a few cases, we needed to stop the vehicle for positive identification; during these times we did not include new observations. Because of time and distance constraints, time in each habitat was not uniform. We determined species richness and abundance by habitat type. We used curve-fitting software (Curve- Expert©, 1995-2001; Daniel Hyams, Version 1.37) to demonstrate how richness increased with increasing number of km surveyed. CurveExpert© uses double-pre- cision floating-point numbers to calculate and rank best- fit curves. In this manner, we describe the rate of species accumulations in each habitat type and include the cor- relation coefficient, r. We analyzed habitat preference for the five species with the greatest abundance (>20 individuals) using a repli- cated goodness-of-fit test (Sokal and Rohlf 1995). We used replicated goodness-of-fit tests to determine wheth- er raptors were distributed in proportion to available habitat, or whether individual raptor species deviated from the expected proportions in the same fashion (i.e., whether G for the pooled data, Gp, and G for the hetero- geneity, Gff, were significant. We did not analyze species with low abundance (<20 observations). Results We traveled 518 km through agricultural habitat, 381 km through the mixed agriculture/mesquite habitat, 216 km through pure mesquite habitat, and 133 km through desert-scrub grasslands. We counted 12 species of raptors and vultures totaling 776 individuals (Table 1). Agricul- tural lands had the lowest relative richness and highest relative abundance (1.5 species/100 km, 74.9 individu- als/100 km), while desert scrub had the highest relative richness and lowest relative abundance (6.0 species/ 100 km, 46.6 individuals/ 100 km; Table 1). The raptor ob- servations for the four habitat types were determined to have the following species accumulation curves (Fig, 2): the MMF model (Morgan et al. 1975) for agriculture {y = [ab + cxV][b + x*^]; a = —8.78; b = 0.90; c = 11.03; d = 0.29; SE = 0.45; r = 0.99); the logistic model for mixed argriculture/mesquite(y = a/(l + b X e”*^’'); a = 9.51; b = 4.07; c = 0.038; SE = 0.79; r= 0.97); the Power Fit for mesquite {y = ax*’; a = 0.14; b = 0.68; SE = 0.92; r = 0.94); and the rational function model for desert- scrub grasslands (y = (a + bx)/ (1 + cx + dx^); a = 0.23; b = 0.83; c = 0.11; d = -0.0001; SE = 0.26; r= 0.99). June 2004 Short Communications 155 Agriculture Mixed Agriculture-Mesquite • 1 1 8 • r * 0 • 9 W • • • ! E ’ 1 < • 2 ^ - • a 1 « \ » • ( 1 n 100 iM m HO M* i M M 70 too m ICO Oi»Uac« Travekd (km) DisUncc Travakd (kai) Mesquite Desert-Scrub Grasslands o -= ‘ 1 « i r j 9 1 ■ • i \ ' 0 ♦ ■8 • i ' • i 1 B 9 Z. • z m t •» ■* * • 4 i I 00 100 ^ »a 790 MO 1 1 H l« H 100 m 100 OkUaco T (km) Oktanc* Trav«kd (km) Figure 2. Species accumulation curves for raptors encountered during roadside surveys of four habitat types in Argentina. Of the 12 species observed, we recorded 7 infrequent- ly: Aplomado Falcon {Falco femoralis), White-tailed Kite {Elanus leucurus), Red-backed Hawk {Buteo polyosoma) , White-tailed Hawk {B. aUncaudatus) , Short-eared Owl (Asio flammeus), Turkey Vulture {Cathartes aura), and Black Vulture {Coragyps atratus). Chimango Caracaras {Milvago chimango). Crested Caracaras (Caracara plancus) , American Kestrels {F. sparverius), migratory Swainson’s Hawks {B. swainsoni), and Burrowing Owls {Athene cuni- cularia) were most common. Chimango Caracaras {N = 490) were most frequently found in agriculture or mixed agriculture/mesquite and Crested Caracaras {N = 172) were most frequently found in mesquite. These two spe- cies occurred in all habitats and accounted for 85% of the total number of individuals sighted. American Kes- trels {N = 20) were recorded infrequently, but also oc- curred in all surveyed habitats (Table 1). Swainson’s Hawks and Burrowing Owls were found most commonly in agriculture. We often found Chimango Caracaras, Crested Caracaras, and Swainson’s Hawks in groups (Ta- ble 2). A replicated goodness-of-fit test on the five most com- mon species indicated that raptors were not distributed in proportion to available habitat. The pooled goodness- of-fit test {Gp = 43.8; df = 2; P < 0.001) indicated that the raptor community as a whole was observed in habitats in proportions different from those available. In partic- ular, raptor abundance in agricultural lands exceeded the proportion of available habitat. The heterogeneity goodness-of-fit test {Gff = 173.1; df = 12; P < 0.001) indicated that individual raptor species did not all deviate from the expected proportions in the same fashion. All individual goodness-of-fit tests also were significant (Ta- ble 3) . American Kestrels used mesquite and agriculture/ mesquite habitats. Crested Caracaras used mesquite, and Burrowing Owls used agriculture or mesquite. Both Chi- mango Caracaras and Swainson’s Hawks were observed largely on agricultural lands. Discussion Our results show that the five most commonly encoun- tered species chose habitats differently and not in pro- 156 Short Communications VoL. 38, No. 2 Table 2. Group sizes of species observed on roadside surveys. No. Individuals 1 2 3 4 5 6-10 >10 Species American Kestrel 16 2 Aplomado Falcon 1 2 Chimango Caracara 200 61 17 7 7 4 2 Crested Caracara 81 22 7 4 1 Swainson’s Hawk 1 1 1 2 Red-backed Hawk 6 White-tailed Hawk 2 2 Burrowing Owl 6 2 1 Turkey Vulture 8 2 Black Vulture 2 3 portion to their availability. Chimango Caracaras were more abundant than other species we encountered, sim- ilar to findings from other roadside surveys in Argentina. Chimango Caracaras accounted for 54% of all observa- tions in Patagonia (Donazar et al. 1993) and 74% of all raptors surveyed in central Argentina (Travaini et al. 1995). Chimango Caracaras, a poorly studied yet com- mon species, use agricultural areas extensively. This spe- cies is often found near trees, foraging on snakes, ro- dents, birds, and insects, depredating nestlings and eggs, eating roadkills, other carrion, and refuse near houses (M. Goldstein unpubl. data). Previous studies, like cur- rent findings, associate Swainson’s Hawks with agricultur- al lands in Argentina, where they forage opportunistically on swarms of grasshoppers (Jaramillo 1993, Goldstein et al. 1999). Opportunistic feeders that forage in groups of- ten are found in association with agricultural fields and rangelands (Ellis et al. 1990, Eakle 1994). Smaller falcons may be more difficult to detect than larger birds, particularly while completing roadside sur- veys at fast speeds. Similarly, our ability to detect falcons may change with habitat type. Detectability of small perching falcons may be reduced with dense habitat structure (Fuller and Mosher 1987). Aplomado Falcons Table 3. Replicated goodness-of-fit test of habitat selection for the five most common raptor species encountered on road surveys in the western pampas and central Argentina. Species numbers are followed by percent observed in parentheses. Agriculture/ Desert Species Agriculture Mesquite Mesquite Scrub Total km 518 381 216 133 1248 (41.5%) (30.5%) (17.3%) (10.7%) G American Kestrel 2 10 7 1 20 12.5* (10%) (50%) (35%) (5%) Burrowing Owl 12 1 7 0 20 15.1* (60%) (5%) (35%) Chimango Caracara 292 138 38 22 490 90.1* (60%) (28%) (8%) (4%) Crested Caracara 42 48 63 19 172 42.7* (24%) (28%) (37%) (11%) Swamson’s Hawk 36 1 0 0 37 56.5* (97%) (3%) Total 384 198 115 42 739 (52.0%) (26.8%) (15.6%) (5.7%) Gh = 173.1* Gp = 43.8* G/ = 216.9* ^ G I — G ^ T Gp . * Significant at a < 0.001. June 2004 Short Communications 157 and American Kestrels perched on fence posts and barbed wires may stand out more than when perched on trees in forested habitats, which may have led to under- counting in the latter. However, electrical and phone wires did not exist across the entire sample area. There were no wires in the desert scrub habitat and wires were intermittent across other regions. In the two habitats with greater tree structure, mixed argriculture/mesquite and mesquite, we detected more kestrels. In a 35-km section of road with electrical wires, through mixed agricultural and mesquite habitat, we detected six American Kestrels on wires. Although we noted no other landscape differ- ences (e.g., ridges or valleys), we do not know whether American Kestrels were more visible on this section of road, wires influenced their visibility, or they simply had greater abundance in this area. Relative richness was inversely correlated with the number of km traveled. Although we observed the great- est relative richness in desert-scrub habitat and the lowest relative richness in agriculture, this dichotomy may have been due to unit effort (Heyer et al. 1994). In other words, if the rapid species accumulations we found in these two habitats were equivocal, then relative richness was a function of sampling effort and we over-estimated its value. Nonetheless, our results indicate that common raptors exhibited distinct landscape preferences, and for the two most common species, Chimango and Crested caracaras, it was likely a result of greater foraging oppor- tunities in disturbed landscapes. Resumen. — Contamos 776 rapaces y buitres a lo largo de estudios al borde de carretera que totalizaron 1248 km durante diciembre de 1998 y Enero de 1999. Viajamos 518 km a traves de habitats agricolas, 381 km a traves de un habitat arbustivo mixto de cultivos agricolas y mes- quite (Prosopis spp.), 216 km a traves de habitat de puro mesquite, y 133 km a traves de desierto arbustivo en las pampas occidentales y el centro de Argentina. De las 10 especies observadas, los caracaras chimango {Milvago chi- mango) y los Caracaras crestados ( Caracara plancus) ocur- rieron a lo largo de todas las rutas estudiadas en todos los habitats y fueron los mas comunes. Las tierras agri- colas tuvieron la mas baja riqueza relativa y la mas alta abundancia relativa, mientras que el desierto arbustivo tuvo la mas alta riqueza relativa y la mas baja abundancia relativa. Un test replicado de bondad de ajuste para las cinco especies mas comunes indico que las especies no estuvieron distribuidas en proporcion al habitat disponi- ble (Gp = 43.8; P < 0.001) y diferentes especies mostra- ron preferencia por diferentes habitats. [Traduccion de Cesar Marquez] Acknowi.edgments We thank A. Lanusse and M. Bechard for logistical sup- port and field assistance while in La Pampa. T. Lacher, M. Corson, K. Kosciuch, J.J. Negro, M. Carrete, and an anonymous reviewer provided critical input for earlier versions of the manuscript. Literature Cited Cade, T.J. 1969. The status of the peregrine and other Falconiformes in Africa. Pages 289—321 in].]. Hickey [Ed.], Peregrine Falcon populations: their biology and decline. Univ. Wisconsin Press, Madison, WI U.S.A. Donazar, J.A., O. Ceballos, A. Travaini, and F. Hirai - DO. 1993. Roadside raptor surveys in the Argentinean Patagonia. /. Raptor Res. 27:106-110. Eakle, W.L. 1994. A raptor roadside survey in western Turkey and Eastern Greece./. Raptor Res. 28:186-191 Ellis, D.H., R.L. Glinski, and D.G. Smith. 1990. Raptor road surveys in South America. /. Raptor Res. 24’98- 106. Fuller, M.R. and J.A. Mosher. 1987. Raptor survey tech- niques. Pages 37-65 mB. Giron-Pendleton, B. Millsap, K. Cline, and D. Bird [Eds.], Raptor management techniques manual. Natl. Wildl. Fed., Washington, DC U.S.A. Goldstein, M.I., T.E. Lacher, Jr., B. Woodbridge, M J. Bechard, S.B. Canavelli, M.E. Zaccagnini, G P Cobb, E.J. Scollon, R. Tribolet, and M.J. Hooper 1999. Monocrotophos-induced mass mortality of Swainson’s Hawks in Argentina, 1995-96. Ecotox. 8. 201-214. Heyer, W.R., M.A. Donneli.y, R.W. McDiarmid, L.C. Hay- EK, and M.S. Foster. 1994. Measuring and monitor- ing biological diversity: standard methods for amphib- ians. Smithsonian Institution Press, Washington, DC U.S.A. Jaramillo, A.P. 1993. Wintering Swainson’s Hawks in Ar- gentina: food and age segregation. Condor 95:475- 479. Leveau, L.M. and C.M. L eveaij. 2002. Uso de habitat por aves rapaces en un agroecosistema pampeano. Hor- nero 17:9—15. Meyburg, B.-U. 1973. Observations sur I’abondance rel- ative des rapaces (Falconiformes) dans le nord et I’ouest de FEspagne. Ardeola 19:129-150. Morgan, P.H., L.P. Mercer, and N.W. Flodin. 1975. Gen- eral model for nutritional responses of higher organ- isms. Proc. Natl. Acad. Sci. 72:4327—4331. Sokal, R.R. AND FJ. Rohlf. 1995. Biometry, 3rd Ed. WH Freeman, NY U.S.A. Travaini, A., A. RodrIguez, O. Ceballos, J. A. Donazar, AND F. Hiraldo. 1995. Roadside raptor surveys in cen- tral Argentina. Hornero 14:64—66. WOFFINDEN, N.D. AND J.R. Murphy. 1977. A roadside rap- tor census in the eastern Great Basin 1973-74. Raptor Res. 11:62-66. Received 3 February 2003; accepted 30 November 2003 Associate Editor: Juan Jose Negro 158 Short Communications VoL. 38, No. 2 J. Raptor Res. 38 (2): 158-1 60 © 2004 The Raptor Research Foundation, Inc. Peregrine Falcons Nesting on Lake Bluefs on the Arctic Coastal Plain of Northern Alaska Robert J. Ritchie^ and Ann M. Wildman ABR, Inc. — Environmental Research ^ Services, P.O. Box 80410, Fairbanks, AK 99708 U.S.A. Clayton M. White Department of Integrative Biology, Brigham Young University, Provo, UT 84602 U.S.A. Keywords: Peregrine Falcon', Falco peregrinus; Arctic, sur- vey, habitat, Alaska. Historically, surveys of birds throughout Alaska have demonstrated clearly that the Peregrine Falcon {Falco per- egnnus) has a dendritic pattern in its breeding distribu- tion because it nested along coastlines or rivers (e.g.. Cade 1960). The best examples of this are the shoreline nest sites on the Aleutian Islands {F. p. pealei) , and along the large rivers of Alaska, such as the Yukon, Tanana, and Colville, and their tributaries {F. p. anatum and tundrius) , but not at isolated montane cliffs away from shorelines and rivers. However, a few isolated cases of nesting by anatum on cliffs near lakes and in upland areas have been reported in interior Alaska. In the lower Kuskokwim Riv- er region, cliffs at two lakes were defended by peregrines m late July (Mindell 1983). Also, cliffs near Tetlin Lake (AK Department of Fish and Game unpubl. data) and at Lake Minchumina (D. Bishop pers. comm.) were occu- pied by peregrines. An adult male with a brood patch was collected on Lake Minchumina in 1955 (C. White unpubl. data) . A pair, possibly nesting, was observed on a cliff at Lake Grosvernor on the Alaska Peninsula (Ca- halane 1959). However, no nest sites have been recorded at lakes in northern Alaska, the range of F. p. tundrius. In 1999, while conducting fixed-wing aerial surveys for raptors primarily along rivers in the National Petroleum Reserve-Alaska (NPR-A) on the Arctic Slope of Alaska, we encountered Peregrine Falcons on mud bluffs at four large lakes (e.g.. Fig. la; Ritchie and Wildman 2000). Pairs and young were observed at two of these bluffs. A single adult was seen defending an apparent nest site at another lake bluff, where young may have been obscured by vegetation. A single adult also was perched near a ledge on a similar soil bluff at a fourth lake. Each sighting occurred on shoreline banks of large lakes in the Oum- alik Lakes region of the southern portion of the Arctic Coastal Plain in the NPR-A (Gallant et al. 199.5). All sites were located between 69°35'N and 69°55'N latitude, and 154°50'W and 155°30W longitude. At least another 10 ^ E-mail address; britchie@abrinc.com lakes with similar shoreline features in this area were checked from the aircraft, but no sign of peregrines was detected at those sites. Our assessment of use of this type of habitat by nesting peregrines was limited because only a few lakes adjacent to our riparian routes were surveyed and because fixed-wing surveys rarely detect all peregrine pairs. For example, sites occupied by failed breeders may have been missed because our surveys were timed to maximize observations of successful nests with large, con- spicuous young. The four bluffs where peregrines were observed were 5-12 m high (e.g., Fig. lb), and falcons at the three sites with young or probable young defended ledges located 4—10 m from the shoreline. Vegetation included low shrubs {Salix sp.) that generally shaded or overhung each ledge. The nest ledges were formed by eroding shore- lines that created a jumble of dirt blocks with cracks and ledges interspersed. All sites were on southern or south- western exposures and were 1.5-2. 5 km from the nearest riparian area. Also these sites with peregrines were on deep, open lakes with little emergent vegetation. Sur- rounding habitats included wet non-patterned (i.e., more homogeneous surface form) tundra, drier upland tus- sock tundra, and sand dunes and willow banks associated with lacustrine and stream shorelines in this area. The use of lacustrine habitats for nesting has not been previously recorded for tundrius in northern Alaska. How- ever, there are records elsewhere in the arctic range of Peregrine Falcons. In a description of 29 sites used by nesting tundrius peregrines in Rankin Inlet, Northwest Territories, Canada, all were within 300 m of substantial waterbodies (i.e., the ocean for most nest sites), includ- ing five sites on the mainland (Court et al. 1988). Some of these inland sites overlooked small lakes (G. Court pers. comm.). In Eurasian regions, such as Scandinavia and the Baltic countries, peregrines commonly nest on the shores of small lakes and in bogs (Kumari 1974, Lind- berg et al. 1988). Finally, peregrines were found to nest on “clayish or sandy precipices of the cliffs of rivers and large lakes” on the west Taimyr Peninsula, Russia (Krech- mar 1966). There are a number of explanations for why nesting pairs have not been identified earlier at lakes in northern June 2004 Short Communications 159 Figure 1. Aerial views of lake habitats on the Arctic Coastal Plain, Alaska: (a) example of a deep open lake used by Peregrine Falcons; (b) ca. nest site of a Peregrine Falcon on lake bluff; (c) general distribution of lakes in a sample of Coastal Plain-Foothill regions transition, which could be suitable habitat for nesting peregrines; and (d) closer view of suitable lakes for Peregrine Falcon nesting. Arrows denote nest-site locations and squares indicate lakes occupied by adult peregrines. Alaska. First, lakes historically have not been searched regularly during raptor cliff-nesdng surveys along rivers on Alaska’s Arctic Slope (ca. 1950-99), where most tun- drius habitat was thought to occur and where known nest sites were found. Instead, major surveys to monitor per- egrine populations in northern Alaska primarily were confined to boat surveys of cliffs along rivers (e.g., Am- brose et al. 1988), with a few helicopter and fixed-wing aircraft surveys in more remote drainages (e.g., Cade and White 1976). Second, Peregrine Falcon numbers were depressed during the 1950s-70s when the region received the great- est attention by biologists interested in the region be- cause of the species’ status and oil exploration (e.g., Haugh 1970, White and Streater 1970, Cade and White 1976, and Ambrose et al. 1988). Without a previous his- tory of use of lake shorelines, lakes were not visited dur- ing these surveys. A third explanation may be the expansion of this re- covering population into “lower-quality” sites that have habitat features similar to adjacent riparian areas that are currently occupied by high densities of peregrines (e.g., Ikpikpuk River; R. Ritchie unpubl. data). As traditional areas have become more “saturated” with birds, lower- quality or less-preferred sites with similar features (e.g., substrate, prey abundance) have become occupied. There also are increasing numbers of sites, once believed marginal for nesting peregrines that are adjacent to tra- ditional habitats, that now are occupied by peregrines in arctic and interior Alaska: man-made sites (e.g., telecom- munication towers), highway banks, and quarries (e.g., Ritchie et al. 1998). A quick assessment of aerial photography of the Arctic Coastal Plain and Foothills regions shows that numerous lakes (Fig. Ic, d), particularly at the southern extent of the Arctic Coasted Plain, may have suitable-habitat fea- tures (i.e., southern exposures, eroding banks, proximity to riparian nesting areas) and provide nesting opportu- 160 Short Communications VoL. 38, No. 2 nities for Peregrine Falcons, Deep open lakes in the Arc- tic Foothills, or at least a transition area between the Arc- tic Coastal Plain and Foothills regions, also may be suitable for nesting peregrines. Indeed, an aggressive pair of Peregrine Falcons was observed near “white- washed ledges” along a shoreline of a lake between the Itkillik and Kuparuk rivers, >150 km southeast from the sites described above (S. Murphy pers. comm.). We rec- ommend that future surveys and monitoring activities to identify Peregrine Falcons nesting in northern Alaska be modified to include large, deep lakes, particularly those in the Arctic Foothills Region and in the transition area between the Arctic Coastal Plain and Foothills regions. Further, with increasing industrial development in north- ern Alaska, surveys may also be warranted to assess pos- sible strategies for protection of this raptor habitat. RtsUMEN. — Registramos la primera anidacion de halco- nes peregrinos {Falco peregrinus) en penascos de lagunas costeras en el norte de Alaska durante estudios aereos de anidacion en cornisas en 1999. Los halcones peregrinos fueron identificados en cuatro lagos en la region de lagos de Oumalik en el Plano Costero Artico. A1 menos dos de estos registros incluyeron observaciones de polluelos de halcon. Acantilados bajos (5-12 m) con repisas nume- rosas formadas por la erosion de la linea costera, y ex- puestas predominantemente hacia el sur o suroccidente, caracterizan cada sitio, Los autores sintetizan la infor- macion sobre nidos lacustres en todo el rango norte del halcon peregrino. Las posibles explicaciones para este re- ciente descubrimiento incluyen un limitado historial de estudios en estas areas, una pobladon de halcones per- egrinos deprimida cuando la actividad de estudios de ra- paces en Alaska fue mas intensa (1950s-70s), y con la recuperacion de la especie, una expansion de la pobla- cion del peregrino en sitios de “mas baja calidad” ady- acentes a sitios con altas densidades de halcones pere- grinos, La distribucion y abundancia relativa de este tipo de habitat en el norte de Alaska, y el potencial para el desarrollo industrial en esta region ameritan la identifi- cacion y aplicacion de consideraciones para la conserva- cion. [Traduccion de Cesar Marquez] ACKNOW1.EDGMENTS The Bureau of Land Management (BLM), Fairbanks, Alaska, provided funding for the aerial surveys described m this paper. Dave Yokel, BLM Wildlife Biologist, in par- ticular, helped to secure funding and provided invaluable logistical support. We are grateful to Dr. Bob Day and John Shook of ABR, Inc., Environmental Research and Services, and two anonymous reviewers for The Journal of Raptor Research, who provided editorial comments on earlier drafts of this paper. Finally, without the safe and expert flying of Sandy Hamilton, Pilot, Arctic Air Alaska, this information would not have been collected. Literature Cited Ambrose, R.E., RJ. Ritchie, C.M. White, P.F. Schempf, T. Swem, and R. Dittrick. 1988. Changes in the status of Peregrine Falcon populations in Alaska. Pages 73- 82 in TJ. Cade, J.H. Enderson, C.G. Thelander, and C.M. White [Eds.], Peregrine Falcon populations their management and recovery. The Peregrine Fund, Boise, ID U.S.A. Cade, TJ. 1960. Ecology of the peregrine and gyrfalcon populations in Alaska. Univ. Calif. Publ. Zool. 63:151- 290. and C.M. White. 1976. Colville River watershed. Pages 245-48 in R.W. Fyfe, S.A. Temple, and T.J. Cade [Eds.], The 1975 North American Peregrine Palcon survey. Can. Field-Nal. 90:228-273. Cahalane, V.H. 1959. A biological survey of the Katmai National Monument. Smithson. Misc. Collect. 138:1- 246. Court, G.S., C.C. Gates, and D.A. Boag. 1988. Natural history of the Peregrine Falcon in the Keewatin Dis- trict of the Northwest Territories. Arctic 41:17-30. Gallant, A.L., E.F. Binnian, J.M. Omernik, and M.B. Shasby. 1995. Ecoregions of Alaska. U.S. Geol. Surv Prof. Paper 1567, Washington, DC U.S.A. Haugh, J.R. 1970. Northern Alaska. Pages 243-244 mT.J Cade and R. Eyfe [Eds.], The North American pere- grine survey, 1970. Can. Field-Nat. 84:231—245. Krechmar, A.V. 1966. Ptitsy Zapadnogo Taimyra. Proc. Zool. Inst. Acad. Sci. USSR. 39:185—312. Kumari, E. 1974. Past and present of the Peregrine Pal- con in Estonia. Pages 230-253 in E. Kumari [Ed.], Estonian wetlands and their life. Acad. Sci. Estonia, “Valgus,” Tallinn, Estonia. Lindberg, R, P.J. Schei, and M. Wikman. 1988. The Per- egrine Ealcon in Pennoscandia. Pages 159—172 in TJ Cade, J.H. Enderson, C.G. Thelander, and C.M. White [Eds.], Peregrine Falcon populations: their manage- ment and recovery. The Peregrine Fund, Boise, ID U. S.A. Mindell, D.P. 1983. Nesting raptors in southwestern Alaska: status, distribution, and aspects of biology U.S. Bureau of Land Manage. Alaska Tech. Rpt. 8., Anchorage, AK U.S.A. Ritchie, RJ. AND A.M. Wildman. 2000. Aerial surveys of cliff-nesting raptors in the National Petroleum Re- serve-Alaska [NPR-A], 1999. ABR, Inc., Fairbanks, AK U.S. A. Ritchie, R.J., T. Doyl.e, and J. Wright. 1998. Peregrine Falcons {Falco peregrinus) nest in a quarry and on highway cutbanks in Alaska./. Raptor Res. 32:261-264. White, C.M. and J.H. Streater. 1970. The oil pipeline and peregrines in Alaska. Page 241 in TJ. Cade and R. Fyfe [Eds.], The North American peregrine survey, 1970. Can. Field-Nat. 84:231-245. Received 28 January 2003; accepted 28 November 2003 Associate Editor: Ian G. Warkentin June 2004 Short Communications 161 J Raptor Res. 38(2):161-163 © 2004 The Raptor Research Foundation, Inc. Unusual Nesting of the Lesser Kestrel {Falco naumanni) in Thessaly, Greece Christos Vlachos,^ Dimitris Bakaloudis, and Evangelos Chatzinikos Aristotle University of Thessaloniki, Department of Forestry and Natural Environment, Laboratory of Wildlife and Freshwater F'isheries, P.O. Box 241, 54006 Thessaloniki, Greece Key Words: Lesser Kestrel-, Falco naumanni; breeding suc- cess-, fledglings-, nesting. The Lesser Kestrel {Falco naumanni) is a small falcon that breeds colonially and nests mainly in walls or roofs of houses, stables, barns, castles or churches, as well as in tree holes, earth cliffs, and in rocky outcrops (Cramp and Simmons 1980). Although the species was consid- ered to be one of the most abundant European birds of prey, it has suffered from a massive population decline in large parts of its western Palearctic range between the 1960s and 1980s (Cramp and Simmons 1980, Biber 1996), now is of global conservation concern (SPEC 1 category), and considered to be vulnerable in Europe (Hagemeijer and Blair 1997). The reasons for the dra- matic decline include the reduction of favorable nesting habitats (restoration and demolition of old buildings), and the intensification of agricultural practices (destruc- tion and loss of foraging areas, and the reduction of prey availability; Donazar et al. 1993, Forero et al. 1996, Telia et al. 1998). The trend of the Greek population, which comprises ca. 14—15% of the European total, has been similar. In Greece, the Lesser Kestrel shows a discontinuous distri- bution and now it is mainly concentrated in Thessaly, where Hallmann (1996) in a preliminary report recorded 104 colonies and a total of 2679 pairs. The objectives of the present study were to estimate the breeding success of Lesser Kestrels nesting on the ground and in a fowl-run with hens and to compare these estimates to those of other colonies. Study Area and Methods Megalo Monastiri is a small village at the southeastern part of the Larisa plain, central Greece. The village is sit- uated on the edge of a hilly terrain, surrounded by grass- lands and agricultural land, where the dominant crops are cereals and cotton, with small areas of almond trees. The altitude ranges from 50-120 m above sea level. The climate IS thermo-mediterranean, with a mild rainy winter and a dry and hot summer. The mean annual precipitation is about 465 mm concentrated during the winter. We located and monitored nests from March— Septem- ber 1999, Most (75%) of the nests were found during the incubation period, while the rest were found at the be- ^ E-mail: cvlachos@for.auth.gr ginning of the egg-laying stage. Nests’ contents were checked every 15 d to record possible reproductive fail- ures, but in three periods they were checked more fre- quently: (1) during the beginning of incubation to assess clutch size; (2) just after hatching to estimate hatching success, brood size at hatching, and date of hatching; and (3) during fledging to record the number of young fledged (Steenhof 1987). A pair which laid eggs was de- fined as a reproductive pair, a successfully-breeding pair was one that fledged at least one young, and breeding success was defined as the percentage of successful ter- ritorial pairs (Newton 1979, Steenhof 1987) . Means ±SE are presented in the text and differences (using the Mann-Whitney U-test and the Fisher’s Exact test for 2 X 2 tables) considered significant at a = 0.05. Results and Discussion A colony of 18 Lesser Kestrel breeding pairs, in an old building in Megalo Monastiri village was recorded in 1998. The next yr, the local municipality demolished the old building and cleared away most of the debris because it was dangerous for the people living in the area. Early in the next breeding season, the same numbers of Lesser Kestrel pairs were recorded at the location of the old build- ing, as most of adult Lesser Kestrels show high fidelity to their breeding colonies (Serrano et al. 2001). We recorded a total of eight breeding attempts of Lesser Kestrels nest- ing on the ground, 75% of which were successful. Al- though ground-nesting behavior had not been observed before, the overall breeding success for these Lesser Kes- trels was slightly higher than that recorded for the entire population in Megalo Monastiri in 1999 (69.7%, N = 33 pairs), but this difference was not significant (Fisher’s Ex- act test, P = 0.569; Bakaloudis et al. 2000). There were no significant differences in any reproduc- tive parameter between the colony that nested on the ground and the population that nested on the buildings of the village. The mean clutch size was 3.1 ± 0.35 eggs, similar to the population in the village (3.5 ± 0.22; Mann-Whitney Latest, P = 0.288). Eighty-four percent of 25 laid eggs on the ground hatched successfully, resulting in a mean brood size at hatching of 2.6 ± 0.26, which was similar to the mean brood size for the pairs nesting on buildings (3.1 ± 0.19, N = 26; Mann-Whitney fktest, P = 0.143). Two of four unhatched eggs disappeared about 14 d after the incubation had begun. In both cases large eggshell fragments were found and we suspect that 162 Short Communications VoL. 38, No. 2 domestic cats {Felis catus) and rats (Rattus rattus) were responsible for destroying those eggs. The mean brood size at fledging per successful pair was lower in the pairs nesting on the ground (2.67 ± 0.33, N — 6) than the pairs nesting in buildings (3.09 ± 0.2, N = 23), but not significantly so (Mann-Whitney U-test, P = 0.371). The mean number of young fledged per reproductive pair that nested on the ground was 2.00 ± 0.5 {N = 8) and did not differ from the mean number of kestrels reared by pairs that nested on the buildings (2.15 ± 0.29, N = 33; Mann-Whitney C-test, P = 0.771). Seventy-six percent ol 21 hatched eggs on the ground produced fledglings successfully. Most chick mortality (80%) occurred when the adults deserted the nests about 20 d after hatching. Although there was indication of the cause of those loss- es, which could be due either to an accident to their parents or to poor parental care, the feathered chicks in two broods (pairs D and H) died from starvation. In an- other case (pair C), the predated downy chick was found close to the nest with its siblings and had probably been killed by a rat. No evidence of cannibalism was observed in the colony of Lesser Kestrel on the ground, as was reported by Negro et al. (1992) for other colonies in Spain. The proportion of nests failing during incubation was lower than pairs nesting on the ground than nesting on buildings (58.3%, N = 7). Conversely, broods in nests on the ground (25%, N = 3) were more likely to fail than those in buildings (16.7%, N = 2; Fisher’s Exact test, P = 0.045). This was due mainly to the higher predation pressure during the nestling stage on pairs nesting on the ground. In general, breeding parameters of the Lesser Kestrel colony on the ground were similar to that of other pop- ulations, except for clutch size, which was lower than in other studies. Variations in clutch size and breeding suc- cess were also reported for other Lesser Kestrel popula- tions (Negro and Hiraldo 1993, Telia et al. 1996) and may be related to changes in food availability from yr to yr or to habitat type (Newton 1979, Negro et al. 1992, Negro and Hiraldo 1993, Telia et al. 1996). The Lesser Kestrel that we studied fed exclusively on insects, mainly crickets and grasshoppers (Orthoptera), the populations of which fluctuate from yr to yr in the study area. The low clutch size of Lesser Kestrels that either nested on the ground or on the buildings in 1999, suggests that the period of study was a yr of food shortage, compared to that recorded for the same study area in 2000 (Bakal- oudis et al. 2000). Finally, the percentage of unhatched eggs was low and similar to the results of other studies (Negro et al. 1993), suggesting that the hatching success either of Lesser Kestrels that nested on ground or on buildings in Megalo Monastiri village was not negatively affected by contamination. However, the widespread use of pesticides in intensive cultivation could be a possible reason for adult deaths or for low feeding rates (i.e., the observed mortality of chicks due to starvation) as these could affect prey populations negatively during the late stage of the nestling period. The fact that Lesser Kestrel relies heavily on prey species that inhabit intensively-cul- tivated land, might be a cause of concern for the future. We also monitored the breeding success of five pairs found nesting in a fowl-run. The mean clutch size was 3.2 eggs (SE = 1.5), brood size 2.8 young (SE = 1.3), and breeding success 60%. Sixty-nine percent of 16 laid eggs hatched successfully and 91% percent of the hatched eggs produced fledglings {N = 2) . Between one and three hen eggs were also found in each kestrel nest. Also, one nest was found in a plastic barrel with two eggs, but failed to produce young and another one in an oil barrel with two eggs, which fledged one young successfully. In conclusion, we suggest that the unusual ground- nesting observed, as well as the nesting in fowl-runs and in barrels, may be associated with the lack of other suit- able nesting sites (Forero et al. 1996), the relative ab- sence of predators (Balfour 1955, Seago 1967, Piechocki 1982, Village 1990) at this site and by the high fidelity exhibited by adults to their breeding colonies (Serrano et al. 2001). Resumen. — Presentamos informacion sobre 8 nidos de Falco naumanni que han hecho nido en el suelo debajo de los restos de un edificio antiguo demolido en Thes- salia, Grecia Central en 1999. Las variables reproductivas como tamapo de puesta en el momento del vuelo (3.1 huevos puestos), el tamapo de pollada (2.6 polios) y exito reproductor (2.6 polios) no tienen diferencias importan- tes comparados con los que han sido observados en in- stalaciones humanas en la misma region de estudio. En el 75% de los nidos se ha criado con exito al menos un polio, con un promedio de 2.0 polios por pareja reprod- uctora. Cinco parejas han .sido localizadas en gallineros usando los mismos nidos de las gallinas y tres de ellos criaron polios con exito. Una puesta fue encontrada en un cubo de plastico y otra en un barril de aceite. [Traduccion de los autores] ACKN OWI .EDGMENTS We would like to thank E. Vlachou, E. Dafos, V. Bot- zorlos, T. Papadopoulos, and D. Tsalagas for their assis- tance with the fieldwork. We are also grateful to the 4th Hunting Federation of Sterea Hellas and Municipal En- terprise and Ecotourist Center of Dadia, which have sup- ported this research financially. We also thank Drs. J.J Negro, D. Serrano, and an anonymous referee who re- viewed and greatly improved this manuscript. Literature Cited Balfour, E. 1955. Kestrel nesting on the ground in Ork- ney. Bird Notes 26:245-253. Bakaloudis, D., C. Viachos, and E. Chatzinikos. 2000. Breeding success in the Lesser Kestrel Falco naumanm in Thessaly, central Greece. Conference for Birds of Prey and Owls, 22-26 November 2000. Mikulov, Czech Republic. Biber, J.P. 1996. International action plan for the Lesser June 2004 Short Communications 163 Kestrel (Falco nauvtanni). Pages 191-203 in B. Here- dia, L. Rose, and M. Painter [Eds.], Globally threat- ened birds in Europe. Couneil of Europe Publishing, Berlin, Germany. Cramp, S. and K.E.L. Simmons. 1980. The birds of the western palearctic. Vol. 2. Hawks to bustards. Oxford Univ. Press, Oxford, U.K. Donazar, J.A., JJ- Negro, and P. Hiraldo. 1993. Forag- ing habitat selection, land-use changes and popula- tion decline in the Lesser Kestrel Falco naumanni. / Applied Ecol. 30:515-522. Forero, M.G., J.L. Telia, J.A. Donazar, and F. Hiraldo. 1996. Can interspecific competition and nest site availability explain the decrease of Lesser Kestrel Falco naumanni populations? Biol. Conserv. 78:289—293. Hageme^er, W.J.M. and MJ. Biair. 1997. The EBCC At- las of European Breeding Birds: Their Distribution and Abundance. T. 8c A.D. Poyser, London, U.K. Hallmann, B. 1996. Lesser Kestrel survey: Thessaly 1995. Report to the Hellenic Ornithological Society, Thes- saloniki, Greece. Negro, J J-, J-A. DonAzar, and F. Hiraldo. 1992. Klep- toparasitism and cannibalism in a colony of Lesser Kestrels {Falco naumanni).]. Raptor Res. 26:225-228. , J.A. DonAzar, F. Hiraldo, L. Hernandez, and M. FernAndez. 1993. Organochlorine and heavy met- al contamination in non-viable eggs and its relation to breeding success in a Spanish population of Lesser Kestrels {Falco naumanni). Environ. Pollut. 82:201-205. , and F. Hiraldo. 1993. Nest-site selection and breeding success in the Lesser Kestrel Falco naumanni Bird Study 40: 1 1 5-1 19. Newton, 1. 1979. Population ecology of raptors. T. & A D. Poyser, London, U.K. PiECHOCKi, R. 1982. Der Turmfalke. Ziemsen-Verlag, Wit- tenberg, Germany. Seago, M.J. 1967. The birds of Norfolk. Jarrold 8c Son, Norwich, U.K. Serrano, D., J.L. Telia, M.G. Forero, andJ.A. DonAzar 2001. Factors affecting breeding dispersal in the fac- ultatively colonial Lesser Kestrel: individual experi- ence vs. conspecific cues. J. Animal Ecol. 70:568-578. Steenhof, K. 1987. Assessing raptor reproductive success and productivity. Pages 157—170 m B.A.G. Pendleton, B.A. Millsap, K.W. Cline, and D.M. Bird [Eds.], Rap- tor management techniques manual. Nat. Wildl. Fed , Washington, DC U.S.A. Telia, J., F. Hiraldo, J. DonAzar, and J. Negro. 1996. Costs and benefits of urban nesting in the Lesser Kes- trel. Pages 53-60 in D. Bird, D. Varland, and J.J. Negro [Eds.], Raptors in human landscapes. Academic Press Ltd., London, U.K. , M.G. Forero, F. Hiraldo, and J.A. DonAzar 1998. Conflicts between Lesser Kestrel conservation and European agricultural policies as identified by habitat use analysis. Conserv. Biol. 12:593-604. Village, A. 1990. The kestrel. T. & A.D. Poyser, London, U.K. Received 29 January 2003; accepted 29 December 2003 Associate Editor: Juan Jose Negro J Raptor Res. 38(2) : 163-1 68 © 2004 The Raptor Research Foundation, Inc. Fat Stores of Migrant Sharp-shinned and Cooper’s Hawks in New Mexico John P. DeLong^ HawkWatch International, Inc., 1800 South West Temple, Suite 226, Salt Lake City, UT 84115 U.S.A. and Department of Biology, Utah State University, 5305 University Blvd., Logan, UT 84322 U.S.A. Stephen W. Hoffman^ HawkWatch International, Inc., 1800 South West Temple, Suite 226, Salt Lake City, UT 84115 U.S.A. Key Words: Cooper’s Hawk, Accipiter cooperii; Sharp- shinned Hawk; Accipiter striatus; avian energetics; migration; fat scores; fat stores. 1 Present address: 2314 Hollywood Ave. NW, Albuquer- que, NM 87104 U.S.A.; e-mail address: jpdelong® comcast.net ^ Present address: Audubon Pennsylvania, 100 Wildwood Way, Harrisburg, PA 17110 U.S.A. Birds use stored fats to supply energy during times when foraging is limited or not possible (King 1970, Blem 1980). During migration, stored fat allows birds to make uninterrupted flights between places and times when foraging can occur and fat stores can be replen- ished (King 1970, Blem 1980). The amount of fat that birds store during and leading up to migration varies widely (Blem 1980). Fat stores ranged from 4% of total body mass in Common Buzzards {Buteo buteo vulpinus) migrating through Israel (Gorney and Yom-Tov 1994) to 164 Short Communications VoL. 38, No. 2 32% of total body mass in Pacific Golden-Plovers {Pluvi- alis fulva) preparing to cross the Pacific (Johnson et al. 1989). Presumably, the amount of fat stored is adaptive and relates to the amount of energy needed to fuel flights between predicted stopover sites where fat stores can be replenished (King 1970, Blem 1980, 1990), Al- though many studies have investigated fat stores in mi- grating songbirds and shorebirds (Blem 1980), only a few have examined the fat stores of migrating raptors (Ges- saman 1979, Smith et al. 1986, Harden 1993, Gorney and Yom-Tov 1994). Sharp-shinned {Accipiter striatus) and Cooper’s hawks (A cooperii) are medium-range-partial migrants often ob- served migrating along mountain ridges and coastlines across much of North America (Kerlinger 1989). We cap- tured Sharp-shinned and Cooper’s hawks during spring and fall migration in central New Mexico and used equa- tions developed by DeLong and Gessaman (2001) to es- timate their fat stores. In this paper, we describe fat stores m these migrating hawks and examine differences by mi- gration season, species, age, and sex. Methods We captured hawks at two sites in central New Mexico where HawkWatch International, Inc., conducts long- term raptor migration studies (Hoffman et al. 2002). The spring study site is located at the south end of the Sandia Mountains in the Cibola National Forest, ca. 18 km east of Albuquerque (35°05'N, 106°26'W). The spring band- ing season generally began on 10 March and lasted through late April, and we used data collected from 1994-96. The fall study site is located in the Manzano Mountains in the Cibola National Forest, ca. 56 km south- southeast of Albuquerque (34°42'N, 106°24'W) and 34 km south of the Sandia site. The fall banding season gen- erally began on 1 September and lasted through late Oc- tober, with peak flights occurring in late September and early October (DeLong and Hoffman 1999). We used data collected from 1992-96. Sharp-shinned and Coo- per’s hawks migrating through these sites are using the Rocky Mountain Flyway described in Hoffman et al. (2002). Birds captured at these sites appear to breed from New Mexico north to Alberta and winter primarily m southwestern Mexico (Hoffman et al. 2002). We captured hawks as described in Hoffman et al. (2002). We used plumage characters to determine age (adult and immature; Mueller et al. 1979, 1981) and size to determine sex (Hoffman et al. 1990). We measured mass to the nearest 1 g (using an electronic balance) and tarsus length (Hoffman et al. 1990) to the nearest 0.1 mm (using calipers). We examined birds for the pres- ence of food in their crop (esophageal pouch) and here- after refer to “cropped” birds (with food detectable in the crop) and “uncropped” birds (with no food detect- able). We assigned fat scores to birds using the subalar fat pad located under the wing on the bird’s right side with the 4-point (0-3) classification system described in DeLong and Gessaman (2001). Scores were assigned as follows: 0 for birds with no visible fat, 1 for birds with a shallow streak of fat, 2 for birds with fat that was approx- imately flush with surrounding muscle tissue, and 3 for birds with fat that exceeded the depth of the surround- ing muscle tissue. Birds were released promptly after pro- cessing. We estimated the fat stores for each bird using a model with body mass and tarsus length as predictor variables (DeLong and Gessaman 2001). These models were based on fat extraction techniques that allowed known fat stores to be regressed against structural size measure- ments and mass. The four models were specific to species and sex classes: In (Y) cooper’s Hawk, female = 3.1380 + 0.0149 X M - 0.0881 X T (1) ln(Y)cooper's Hawk, male = 9.9095 + 0.0149 X M - 0.1868 X T (2) In ( Y) sparp-shinned Hawk, female “ “0.1362 + 0.0437 X M “ 0.0881 X T (3) In (Y) Sharp-shinned Hawk, male = 6.6353 + 0.0437 X M “ 0.1868 XT (4), where M = mass in g, T = tarsus length in mm, and Y = fat stores in g. We took the antilog of the values pro- duced by these equations (eto the power of the equation output) to get an estimate of the total grams of fat stored by each bird. We limited our dataset in three ways. First, the esti- mated fat stores for migrating hawks produced by equa- tions 1-4 exceeded the range of fat stores in the calibra- tion sample (up to about 70 g fat in the calibration sample; DeLong and Gessaman 2001). Although the cal- ibrated model was linear, we felt that only modest use of data beyond the calibration range was justified. An ex- amination of a histogram of fat stores for migrants indi- cated that an appropriate upper cutoff to use in this study was a fat store of 100 g, and we excluded from all analyses captured birds with estimated fat stores that ex- ceeded this level (55 individuals excluded). Second, we excluded cropped birds from these analyses because equations 1-4 were derived using birds that were un- cropped or from which crop contents were removed. In- cluding cropped birds in the analysis would allow the ex- tra mass of the crop contents to inflate the estimates of fat stores. To determine whether cropped birds carried different amounts of body fat than uncropped birds, we compared fat scores of cropped and uncropped birds for each spe- cies, age, and sex class captured during each migration season using chi-square tests. We made 16 comparisons and used a Bonferroni-adjusted significance value of 0.003 for these tests (0.05/16). Third, we included data only if collected by a bander that participated significantly in the study (i.e., had processed more than 100 birds during the study period) and excluded all other data. To simplify comparing groups of birds that differed widely in body mass (i.e., species and sex classes), we cal- culated percent total body fat: (fat stores/body mass) X 100. We square-root-transformed the resulting values to remove the positive skew in the data. We used 3-way AN- OVA for each species to examine season, age, and sex differences in fat stores, using transformed percent total body fat as the dependent variable. We conducted anal- yses using SYSTAT v. 7.01 (SPSS Inc. 1997). June 2004 Short Communications 165 Table 1. Estimated percent total body fat for Sharp-shinned and Cooper’s hawks captured during fall (Manzano Mountains, 1992-96) and spring (Sandia Mountains, 1994-96) migration with empty crops in central New Mexico Species Age and Sex Fall Spring X SE N X SE N Sharp-shinned Hawk Adult female 6.75 0.18 389 9.95 0.74 71 Adult male 5.25 0.12 202 6.05 0.39 24 Immature female 4.18 0.1 347 6.79 0.6 28 Immature male 4.74 0.12 264 4.87 0.47 6 Cooper’s Hawk Adult female 9.45 0.2 314 10.62 0.24 224 Adult male 4.64 0.13 245 4.62 0.12 230 Immature female 5.52 0.16 238 9.07 0.57 28 Immature male 3.69 0.11 188 4.15 1.05 3 Results Fat stores in Sharp-shinned and Cooper’s hawks mi- grating in central New Mexico were generally low, aver- aging 3-12% of total body mass (Table 1, Fig. 1). Fat scores of cropped and uncropped birds did not differ by species, age, or sex during either season (x% or 2 ^ P > 0.025). This indicates our use of only uncropped birds to estimate fat stores was justified and resulted in a representative sample. Fat stores of Sharp-shinned Hawks varied significantly Figure 1. Estimated mean (±SD) percent total body fat for (A) Cooper’s Hawks and (B) Sharp-shinned Hawks captured with empty crops during spring (solid circles, 1994-96; Sandia Mountains) and fall (open cir- cles, 1992-96; Manzano Mountains) migration in cen- tral New Mexico. across season, age, and sex (Table 1, Fig. 1). Overall, per- cent total body fat was higher in spring than in fall, high- er for adults than for immatures, and higher for females than for males; however, significant interactions modified all of these main effects (Table 2). The differences in percent total body fat by season were large for females, and this d i fference was greater in immature females than in adult females. In contrast, males showed relatively little seasonal variation, with only adult males having more fat in spring than in fall. The difference in percent total body fat by age occurred primarily for females, with males showing little age-related differences. Fat stores of Cooper’s Hawks also varied significantly across season, age, and sex (Table 1, Fig. 1). The pattern of differences was very similar to that of Sharp-shinned Hawks. However, female Cooper’s Hawks showed higher percent total body fat than female Sharp-shinned Hawks and male Sharp-shinned Hawks showed marginally high- er percent total body fat than male Cooper’s Hawks. Oth- erwise, variation by site, age, and sex mirrored closely the variation of Sharp-shinned Hawks with one notable ex- ception: adult male Cooper’s Hawks showed the same percent total body fat in spring and fall (Table 1). Discussion Average fat stores in migrating raptors have been esti- mated at 4—5% of body mass for Common Buzzards in Israel (Gorney and Yom-Tov 1994), 6—9% for American Kestrels {Falco sparverius), 6—11% for Sharp-shinned Hawks, and 14-18% for Merlins {F. columbarius) in New Jersey (Harden 1993). Our results, in combination with these previous estimates, indicate that many raptors mi- grate with fat stores in the range of 4—18% of body mass. Migration season was an important source of variability in fat stores. In females of both species, fat stores were higher in spring than in fall (Table 1, Fig. 1). These dif- ferences were not seen in males, except for adult male Sharp-shinned Hawks. One possible adaptive advantage of females having high spring fat stores is that they may 166 Short Communications VoL. 38, No. 2 Table 2. Three-way analyses of variance examining variation in transformed (square-root) percent total body fat by season, age, and sex for 1331 Sharp-shinned Hawks and 1470 Cooper’s Hawks captured during spring (Sandia Moun- tains, 1994-96) and fall (Manzano Mountains, 1992-96) migration in central New Mexico. Factor Sharp-shinned Havvk Cooper’s Hawk 74, 1323 P F \, 1462 P Season 23.4 <0.001 10.6 0.001 Age 27.0 <0.001 18.3 <0.001 Sex 16.6 <0.001 125.1 <0.001 Season X age 0.1 0.79 4.0 0.046 Season X sex 9.9 0.002 6.1 0.013 Age X sex 6.2 0.013 4.3 0.039 Season X age X sex 0.4 0.552 1.4 0.241 use those fat stores to aid in developing eggs when spring migration ends and they enter the breeding period. New- ton (1979) found that female European Sparrow Hawks (A nisus) that did not reach a minimum body mass dur- ing courtship failed to lay eggs; this failure to lay eggs could potentially be avoided by accumulating fat stores before or during spring migration. In both Sharp- shinned and Cooper’s hawks, adult females showed high- er spring fat stores than immatures. This difference may be related to the higher likelihood of adults breeding compared to immatures; however, some female Sharp- shinned and Cooper’s hawks breed in their first yr (Ro- senfield and Bielefeldt 1993, Bildstein and Meyer 2000, Boal 2001). Nevertheless, Boal (2001) found that females that breed in their first yr (immatures) have later, smaller, and less successful nests than adults. Boal (2001) cited the possibility of physiological constraints as one possible reason for these differences, a constraint that may be re- flected in this study as relatively low percent total body fat during spring migration. Adult females had the highest fat stores among both spring and fall migrants (Table 1, Fig. 1). Sex-specific dif- ferences in the fall were less consistent. In the fall, im- mature female Cooper’s Hawks showed higher fat stores than immature male Cooper’s Hawks, but the reverse was true for Sharp-shinned Hawks. There may be advantages for females to maintain higher fat stores. Aside from the benefit of carrying extra fat stores prior to the breeding period, females may maintain higher fat stores than males for reasons relating to migration strategies, prey prefer- ences, foraging efficiency, or metabolism. In all cases except for male Cooper’s Hawks in the spring, adults showed higher fat stores than immatures. A similar but more modest difference was observed in spring migrant Common Buzzards in Israel (4% for im- matures versus 5% for adults; Gorney and Yom-Tov 1994), and many migrating passerines show a pattern of higher fat stores in adults than immatures (Woodrey and Moore 1997). For raptors, one clear difference between adults and immatures is hunting experience. It is possible that the net energy gained from prey captures is lower for immatures than adults because of the time spent or the number of attempts made prior to acquiring prey. Such a difference would make capturing prey more ex- pensive, thereby reducing the energy stores gained per prey item. Under such a scenario, the age difference should be reduced during spring migration because of the additional hunting experience acquired by imma- tures during the winter. A reduction was observed only for female Cooper’s Hawks (Table 1 ) , suggesting that the factors that constrain immatures to lower fat stores than adults are maintained through spring migration. Alter- natively, the age-specific difference shown in the spring may reflect an age-specific difference in the optimal level of fat stores needed (Lima 1986). How raptors optimize their fat stores (i.e,, how they balance the costs and ben- efits of acquiring and carrying fat stores) has yet to be investigated. One potential caveat for these results is that there may be a bias in the sampling methodology. Capturing ani- mals by using food as a lure has the potential to result in the capture of an elevated number of food-stressed individuals, relative to the proportion in the migrant pop- ulation. This bias has been termed “condition bias” by Gorney et al. (1999) and it suggests that the estimated fat stores presented here may underestimate those of the entire migratory population, assuming that there is a re- lationship between fat stores and a propensity to respond to food lures. Nevertheless, unless condition bias oper- ates differently across season or species, age, and sex groups, our data should portray accurately the pattern of variation in fat stores related to these factors. In summary, we found low but highly variable levels of fat stores in Sharp-shinned and Cooper’s hawks migrat- ing through central New Mexico. These complex pat- terns merit further investigation, especially because most work investigating fat stores in migrating birds has fo- cused on passerines and shorebirds. Given the variable migration distances (Kerlinger 1989), flight strategies (Kerlinger 1989, Spaar 1997), and foraging behaviors June 2004 Short Communications 167 (Kirkley 1991, Candler and Kennedy 1995, Yosef 1996) of migrating raptors, there may be considerable variation in the need for internal energy storage. The actual rela- tionships between fat stores and the flight strategies, for- aging patterns, and metabolic energy needs of migrating hawks have yet to be described. Resumen. — Las reservas de grasa son un substrate de emergia importante para las aves migratorias, sin embar- go aun existe poca informacion sobre los depositos de grasa que llevan las rapaces migratorias. Estimamos los depositos de grasa de los gavilanes listados (Accipiter stria- tus) y los gavilanes de Cooper (A. cooperii) que migraron durante la primayera (1994-96) y el otono (1992-96) en Nuevo Mexico. Los depositos de grasa promediaron 3— 12% de la masa corporal total. Hubo una variacion sig- nificativa en los depositos de grasa por estacion, edad, y sexo, y ocurrieron interacciones significativas entre estos efectos. Tres patrones fueron reconocidos: depositos de grasa mas grandes para las hembras en la primavera que para los machos en otono, y depositos de grasa mas gran- des para los adultos que para los inmaduros. Los gavila- nes que tenian comida en su bolsa esofagal (buche) no tuvieron grados de grasa diferentes (grasa subcutanea vis- ible) que los gavilanes sin comida en sus buches. Estos resultados sugieren que la variacion en los patrones de deposito de grasa en aves rapaces migratorias son com- plejas y ameritan mayores estudios. [Traduccion de Cesar Marquez] Acknowledgments We would like to thank the many dedicated volunteers and field technicians who made the Manzano and Sandia projects successful. We also thank the following agencies and corporations for financially and logistically support- ing the work at our study sites: U.S. Forest Service, Cibola National Forest; New Mexico Department of Game and Fish, Share With Wildlife Program; U.S. Fish and Wildlife Service, Region 2; Central New Mexico Audubon Society; and Intel Corporation. Many local businesses and indi- viduals donated food and supplies to field crews. We thank C. Boal, J. Fry, J. Gessaman, L. Goodrich, J. Kelly, P. Kennedy, C. Lott, T. Meehan, J. Smith, R. Smith, K. Sullivan, M. Vekasy, and an anonymous reviewer for mak- ing helpful comments on this manuscript and J. Jewell for her ongoing moral support and patience. Literature Cited Bildstein, K.L. AND K. Mever. 2000. Sharp-shinned Hawk. In A. Poole and F. 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Fat cyclicity, predicted migratory flight ranges, and features of wintering behavior m Pacific Golden-Plovers. Condor 91:156-177. Kerlinger, P. 1989. Flight strategies of migrating hawks. University of Chicago Press, Chicago, IL U.S.A. King, J.R. 1970. Adaptive periodic fat storage by birds. International Ornithological Congress 25:200—217. Kirkley, J.S. 1991. Do migrant Swainson’s Hawks fast en- route to Argentina? /. Raptor Res. 25:82-86. Lima, S.L. 1986. Predation risk and unpredictable feed- ing conditions: determinants of body mass in birds. Ecology 67:377-385. Mueller, H.C., D.D. Berger, and G. Allez. 1979. Age and sex differences in size of Sharp-shinned Hawks. Bird-Banding 50:34—44. , , AND . 1981. Age, sex, and seasonal differences in size of Cooper’s Hawks. /. Field Ornithol 52:112-126. Newton, I. 1979. Population ecology of raptors. Buteo Books, Vermillion, SD U.S.A. Rosenfield, R.N. and J. Biei.efei.dt. 1993. Cooper’s Hawk. In A. Poole and F. Gill [Eds.], The birds of North America, No. 75. The Birds of North America, Inc., Philadelphia, PA U.S.A. Smith, N.G., D.L. Goldstein, and G.A. Bartholomew. 168 Short Communications VoL. 38, No. 2 1986. Is long-distance migration possible for soaring hawks using only stored fat? Auk 103:607-611. Spaar, R. 1997. Flight strategies of migrating raptors: a comparative study of interspecific variation in flight characteristics. Ibis 139:523-535. SPSS, Inc. 1997. SYSTAT® 7.0: Statistics. SPSS, Inc., Chi- cago, IL U.S.A. WOODREY, M.S. AND F.R. MooRE. 1997. Age-related dif- ferences in the stopover of fall landbird migrants on the coast of Alabama. Auk 114:695—707. Yosef, R. 1996. Raptors feeding on migration at Eilat, Israel: opportunistic behavior or migratory strategy? J. Raptor Res. 30:242-245. Received 21 June 2003; accepted 28 December 2003 J. Raptor Res. 38(2):168-174 © 2004 The Raptor Research Foundation, Inc. Spanish Ringing and Recovery Records of Booted Eagle {Hieraaetus pennatus) Ignacio S. Garcia Dios^ Instituto de Investigadon en Recursos Cinegeticos (C.S.I.C.-U.C.L.M.), Ronda de Toledo s/n, 13005 Ciudad Real, Spain Key Words: Booted Eagle-, Hieraaetus pennatus; mortality, longevity, philopatry. Scientific ringing is a useful method to study many as- pects of the life history of birds, and is especially impor- tant for the study of migration. Information about mi- gratory routes and wintering areas of raptors is necessary for understanding the factors affecting the conservation of these species outside the breeding areas, such as hab- itat loss, environmental contamination, or human inter- ference (Zalles and Bildstein 2000). This is particularly relevant for raptor species that perform long migratory journeys, which may be especially vulnerable to human impacts. Furthermore, the concentration of a large num- ber of individuals during migration increases the poten- tial for natural and antropogenic impacts such as shoot- ing and trapping (Zalles and Bildstein 2000). The Booted Eagle {Hieraaetus pennatus) breeds in southern Europe and winters in Africa (Cramp and Sim- mons 1980). In winter, Booted Eagles breeding in Eu- rope may move southward into the area where Booted Eagles nest in southern Africa (Brooke et al. 1980, Pepler et al. 2001, D. Pepler and R. Martin unpnbl. data). There are some data on the numbers of Booted Eagles crossing the Gibraltar Strait (Bernis 1973, Garzon 1977, Cramp and Simmons 1980, Finlayson 1992, Zalles and Bildstein 2000), the Messina Strait (Thiollay 1989, Zalles and Bild- stem 2000), the western Pyrenees (Iribarren 1973, Zalles and Bildstein 2000), the Bab-el-Mandeb Strait (Welch and Welch 1989, Zalles and Bildstein 2000), and other localities during post-nuptial migration to Africa (Zalles * Present address: Plazuela del Padre Felipe Fernandez n° 1-2°, 05416, EL ARENAL Avila, Spain; e-mail address: pennatus@latinmail.com and Bildstein 2000) . However, little is known for this spe- cies about the routes used during migration to Africa, wintering areas, use of stop-over sites during migration, habitat use in wintering areas, threats outside the breed- ing season, where first-yr birds spend their second sum- mer, and philopatry. This paper presents a first analysis of ringing and recovery records of this species in Spain for mortality rates, migratory rontes, dispersal move- ments, and longevity in the Booted Eagles. Methods Ringing data presented in this paper were obtained from the Ringing Office of the Spanish General Direc- tion of Nature Conservation. These include only recov- eries of Booted Eagles ringed in Spain. From 1973-99, 2080 Booted Eagles were marked with metal rings in Spain (Hernandez-Carrasquilla and Gomez-Manzanaque 2000), of which 80 have been recovered (as of 2001). For this analysis, the recovery records have been divided into four periods: (1) breeding, 15 March-14 September; (2) post-nuptial migration, 15 September-14 November (15 d before of the peak passage through the Gibraltar Strait until the beginning of the wintering period; Bernis 1973); (3) winter, 15 November-14 February (Bernis 1980); and (4) pre-nuptial migration, 15 February-14 March (only one case that has not been included in the analyses). Eagles were classified into one of three age classes: juveniles (<1 yr), immature (2-3 yr), and adults (>3 yr; Newton 1979, Cramp and Simmons 1980). Results and Discussion Causes of Recovery. Erom 80 Booted Eagles ringed in Spain and subseqnently recovered, 58.8% were found dead, 18.8% were found alive and immediately released, and 13.8% were found alive but were not released due to their poor physical condition. No detailed information could be obtained for the remaining 8.8% of ringed ea- June 2004 Short Communications 169 Morocco (W=2) MorotXM} FIv>gino and recovery in Mao (Menorca): distance = 0 km (N = t). R»^ing and recovery in Almonto (Huelva), distanoo - 2 km (A/ - 1). 6km(W=3) and 30 km 1). Ringtftg and recovery in Oo/Mna NatKytal ParV (Huelva); >.^stanc« - 0 km (W - 6) and 27 km (N = 1 1 Ringing and recovery m MadrxJ; dntance = 7 km (A^ = 1). 11 km (W- 1) and 19 km (N- 1) Figure 1. Ringing and recovery localities during breeding period (15 March-14 September) of Booted Eagles marked in Spain. Recoveries of birds that were ringed during the same breeding season were excluded. 0-49 km. 50-99 km . > 99 km . Distance of Ringing Locality (km) Figure 2. Distribution of dispersal distances of Booted Eagles from their natal place during breeding season, ex- cluding data of birds ringed and recovered during the same breeding season. gles. The percentage of birds found dead was greater for juveniles and immatures (combined; 72%, N= 50) than for adults (36.7%, N = 30). This difference was statisti- cally significant (Yate's corrected = 8.26, P = 0,01). This is consistent with the pattern that young raptors tend to have higher mortality rates than adults (Newton 1979). Causes of mortality were: shooting (21.3%), drowning (14.9%), collision with electric powerlines or electrocu- tion (8.5%), trapping (6.4%), general trauma (6.4%), poison (4.3%), predation by other raptors (2.1%), pre- dation by other wild animals (2.1%), collision with cars (2.1%), and unknown (31.9%). Causes of mortality in juveniles were largely related to human activities (drowning 29.2% and shooting 20.8%). The inexperience of juveniles may explain the high num- ber of individuals found drowned (Newton 1979), as this cause of mortality was never recorded for adult birds. The primary cause of mortality for adults was shooting (27.3%), which was also common for juveniles (20.8%) and among immatures (20.0%). Thus, illegal killing seems to be a significant mortality factor for this species, 170 Short Communications VoL. 38, No. 2 Figure 3. Ringing and recovery localities (filled circles) during autumn migration (15 September-14 November) of Booted Eagles marked in Spain. Recoveries within Balearic Islands, where the species is sedentary, have been ex- cluded. including within Spain, where illegal predator control is still an important conservation problem (Villafuerte et al. 1998). With respect to those birds found alive and immedi- ately released, the circumstances of the recovery were trapping (40.9%), found inside buildings (13.6%), found with general trauma (9.1%), or found chilled (4.5%). Among the birds found alive, but not immediately re- leased, 36.4% had general trauma, 27.3% were exhaust- ed, 9.1% had been shot, 9.1% had collided with electric powerlines, and the causes were unknown for the re- maining 18.1%. There were seven records with no infor- mation about the recovery. Dispersal Distances. The longest distances between ringing and recovery locations for Booted Eagles marked in Spain were recorded for birds wintering or migrating m sub-Saharan African countries. The greatest distance record was for an eagle ringed in Alava (northern Spain) and recovered after 1093 d in Burkina Faso (3530 km). Three other records corresponding to long migration journeys were of nestlings ringed in Murcia (southeast- ern Spain) and Donana National Park (province of Huel- va). The first was trapped after 184 d in Nigeria (3110 km) . The second was found predated by a raptor 503 d later in Togo (2980 km). The third was found dead 546 d later in Mali (2708 km). Philopatry. To study dispersal distances after the first wintering season, I selected the recovery records made during the breeding season, excluding the records of birds ringed and recovered during the same breeding season. Of the 32 selected records, 24 (75.0%) were made at a distance less than 100 km from the birthplace (Fig. 1). Seven of these records were made at the same locality where the birds were ringed (six adults and one bird younger than one yr). Raptors tend to be philopa- tric, whereby young birds tend to return to natal areas when they reach breeding age (e.g., Newton 1979, New- ton et al. 1994, Forero et al. 2002), and my results sup- port this for Booted Eagles. With respect to young and immature individuals, 57.1% were recovered between 0-100 km of their birthplace. This suggests that even young, nonbreeding birds may return to their natal areas during the next breeding season. However, there are sev- en cases of Booted Eagles younger than 1 {N = 5) and June 2004 Short Communications 171 Figure 4. Ringing and recovery localities during winter (15 November-14 February) of Booted Eagles marked in Spain. Recoveries within Balearic Islands, where the species is sedentary, have been excluded. 2-yr old {N = 2) recovered very far from their birthplace during the following breeding season (locations of re- coveries were Algeria, Burkina Faso, Mali, and Morocco). The recovery distances were significantly different among age classes (ANOVA with log-transformed dis- persal distances; i^ 2,29 ~ P ~ 0.035; Fig. 2), and this suggests that probably young eagles tend to disperse fur- ther from their natal area than immatures or adult birds during breeding season. In other raptors, the proportion of individuals found near their natal areas increase with age, and young disperse greater distances in the breeding season (Newton 1979). Longevity. The longevity record in the wild was a bird ringed as a nestling in the province of Madrid (central Spain) and recovered dead in a nearby area almost 14-yr later (5084 d-old). A 4638 d-old Booted Eagle ringed in the province of Huelva was also recovered in the Kheni- fra (Morocco). Migration Direction. By using only Booted Eagles ringed and recovered in the same season (the records of the sedentary population in Balearic Islands have been excluded), I obtained a picture of the migration routes for the Spanish population (Fig. 3). The records available showed one movement east-northeast of ringing areas (Caceres), two south-southeast of ringing areas (Cadiz), and one recovered south-southwest of the ringing area (Murcia). Recovery made at east-northeast could be due to a pre-migratory movement of bird looking for a more productive site during summer months, or perhaps rep- resented a bird exploring possible future breeding areas (Newton 1979, Olea 2001). Wintering Areas. Booted Eagles recovered between 15 November and 14 February should reflect wintering ar- eas used by the Spanish population (Fig. 4). I selected 14 records, which can be divided into five groups: two eagles recovered east-northeast of ringing areas (Barce- lona, Spain; Firenze, Italy), five individuals recovered in Africa during winter (Morocco, Togo, Mali, Algeria, and Nigeria; Fig. 5), one sedentary individual (Valencia, Spain), five birds wintering in southern Spain (Cadiz, Huelva, Sevilla) , and one bird wintering in central Spain (Madrid) . 172 Short Communications VoL. 38, No. 2 Figure 5. Recovery locations of Booted Eagles during breeding and winter periods in Africa. June 2004 Short Communications 173 Winter recoveries at east-northeast breeding areas were surprising, because Booted Eagles generally are known to fly south from Europe to Africa (Brown and Amadon 1968, Cramp and Simmons 1980) similar to other Euro- pean migratory raptors (Gonzalez and Merino 1990, Gonzalez 1991, Donazar 1993, Triay unpubl. data). These two winter localities for Booted Eagles, Barcelona and Firenze, are on the Mediterranean coast, where the mild winters could support a high density of passerines and a relatively high winter activity of reptiles. Passerines and reptiles are among the main prey of breeding Booted Eagles in Spain (I. Garcia Dios unpubl. data). Sunyer and Vinuela (1996) and Martinez and Sanchez-Zapata (1999) previously suggested that several raptor species are more frequently wintering in Mediterranean areas over the last 20 yr, instead of migrating to Africa. These two Booted Eagle records are consistent with this suggestion. Despite the lower winter recovery of Spanish Booted Eagles in Africa than in Europe, the primary winter quarters for the species is Africa (Brown and Amadon 1968, Cramp and Simmons 1980). This is clearly supported by the large numbers of birds crossing the Strait of Gibraltar (Bernis 1973). The higher recovery frequency in Europe in this analysis was likely due to higher reporting rates in Europe, and not because more eagles were wintering in Europe. Resumen. — En este articulo presentamos una aproxima- cion sobre la mortalidad, migracion, dispersion, y lon- gevidad del aguililla calzada {Hieraaetus pennatus) basan- donos en las recuperaciones de individuos de esta especie marcados con anillas metalicas. Los resultados sugieren que los jovenes tienen una tasa de mortalidad relativamente alta, en especial debido a su inexperiencia, y que el tiroteo ilegal sigue siendo una causa de mortal- idad importante. Los jovenes tienden a dispersarse ma- yores distancias que los individuos adultos, aunque en general se observa una clara tendencia filopatrica. Se re- gistran movimientos premigratorios e invernada en lati- tudes mas nortenas que las de reproduccion, lo que puede estar relacionado con una tendencia creciente a la sedentarizacion en el Mediterraneo. La m^ima lon- gevidad registrada por este metodo es de 14 anos. [Traduccion del autor] Acknowledgments I thank my wife for her support of my work and for cheering me up during the difficult times of my Doctoral dissertation. 1 also appreciate the support of Manuel Garcia Tornero, Javier Munoz Familiar, and Marcos Gon- zalez Jimenez. The Ringing Office of the Spanish Gen- eral Direction of Nature Conservation provided ringing and recovery data. 1 would also like to thank Juan Go- mendio for reviewing the English version of this manu- script. David Pepler, Javier Vinuela, and two anonymous referees made useful comments on previous drafts. Literature Cited Bernis, F. 1973. Migracion de Falconiformes y Ciconia spp. por Gibraltar, Verano-Otono 1972-73. Primera Parte. Ardeola 19:151-224. . 1980. La migracion de las aves en el Estrecho de Gibraltar. Vol. 1, A.ves planeadoras. Universidad Com- plutense, Madrid, Spain. Brooke, R.K., R. Martin, J. Martin, and E. Martin 1980. The Booted Eagle, Hieraaetus pennatus, as a breeding species in South Africa. Gerfaut 70:297-304. Brown, L. and D. Amadon. 1968. Eagles, hawks, and fal- cons of the world. Country Life Books, London, U.K. Cramp, S. and K.E.L. Simmons. 1980. The birds of the western palearctic. Vol. II. Oxford Univ. Press, Ox- ford, U.K. Donazar, J.A. 1993. Los Buitres Ibericos: biologia y con- servacion. J.M. Reyero, Madrid, Spain. Finlayson, C. 1992. Birds of the Strait of Gibraltar. T. & A.D. Poyser, London, U.K. Forero, M., J.A. Donazar, and F. Hiraldo. 2002. Causes and fitness consequences of natal dispersal in a pop- ulation of Black Kites. Ecology 83:858—872. Garzon, J. 1977. Birds of prey in Spain, the present sit- uation. Pages 159-170 in R.D. Chancellor [Ed.], Pro- ceedings of the World Conference on Birds of Prey, Vienna, 1975. International Council for Bird Preser- vation, Cambridge, U.K. Gonzalez, J.L. and M. Merino. 1990. El Cernicaco prim- illa {Falco naumanni) en la Penisula Iberica. ICONA, Madrid, Spain. Gonzalez Lopez, J.L. 1991. El Aguilucho Lagunero Cir- cus aeruginosus (L., 1748) en Espana: situacion, biol- ogia de la reproduccion, alimentacion y conservacion Ministerio de Agricultura, Pesca y Alimentacion ICONA, Madrid, Spain. Hernandez-Carrasquilia, F. and a. Gomez-Manza- naque. 2000. Informe sobre la campana de anilla- miento de aves en Espana. Ecologia 14:291-330. Iribarren, JJ- 1973. Observacion y recuento de rapaces. Vida Silvestre 12:260-265. Martinez, J.E. and J.A. Sanchez-Zapata. 1999. Invernada del Aguililla Calzada {Hieraaetus pennatus) y Culebrera Europea ( Circaetus gallicus) en Espana. Ardeola 46:93- 96. Newton, I. 1979. Population ecology of raptors. T. & A D Poyser, I^ondon, U.K. , RE. Davis, and D. Moss. 1994. Philopatry and population growth of Red Kites, Milvus milvus, Wales. Proc. R. Soc. Lond. 257:317-323. Olea, P. 2001. Postfledging dispersal in the endangered Lesser Kestrel Falco naumanni. Bird Study 48:110—115. Pepler, D., R. Martin, and H.J. Van Hensbergen. 2001 Estimating the breeding population of Booted Eagles in the Cape Province, South Africa. J. Raptor Res. 35. 15-19. Sunyer, C. and J. Vinuela. 1996. Invernada de rapaces 174 Short Communications VoL. 38, No. 2 (O. falconiformes) en Espana Peninsular e Islas Bale- ares. Pages 361—370 in J. Muntaner and J. Mayol [Eds.] , Biologia y Conservacion de las rapaces Medi- terraneas, 1994. Monograflas No. 4. SEO, Madrid, Spain. Thiollay, J.-M. 1989. Distribution and ecology of palearc- tic birds of prey wintering in west and central Africa. Pages 95-109 in B.-U. Meyburg and R.D. Chancellor [Eds.], Raptors in the modern world: proceedings of the world conference on birds of prey and owls. World Working Group on Birds of Prey and Owls, Ber- lin, Germany. ViLLAFUERTE, R., J. ViNUELA, AND J.C. Blanco. 1998. Ex- tensive predation persecution caused by population crash in a game species: the case of Red Kites and rabbits in Spain. Biol. Conserv. 84:181-188. Welch, G. and H. Welch. 1989. Autumn migration across the Bab-el-Mandeb Straits. Pages 123-125 mB.- U. Meyburg and R.D. Chancellor [Eds.], Raptors in the modern world; proceedings of the world confer- ence on birds of prey and owls. World Working Group on Birds of Prey and Owls, Berlin, Germany. Zalles, J.I. and K.L. Bildstein (Eds.). 2000. Raptor watch; a global directory of raptor migration sites. BirdLife International, Cambridge, U.K. and Hawk Mountain Sanctuary, Kempton, PA U.S.A. Received 27 November 2001; accepted 20 June 2003 J Raptor Res. 38(2) :174-177 © 2004 The Raptor Research Foundation, Inc. Diet Shift of Barn Owls ( Tyto alba) After Natural Fires in Patagonia, Argentina Mercedes Sahores and Ana Trejo^ Centro Regional Bariloche, Universidad National del Comahue, 8400 Bariloche, Rio Negro, Argentina Key Words; Barn Owl; Tyto alba; fire perturbations; dietary shift, Patagonia. The Barn Owl ( Tyto alba) is broadly distributed in Ar- gentina and is found in several types of habitats such as woodlands, grasslands, and semideserts (Canevari et al. 1991). Barn Owls feed primarily on small mammals, al- though prey species differ slightly among different local- ities even in the same geographic region (e.g., in Pata- gonia see Travaini et al. 1997, Pillado and Trejo 2000), which implies that owls show considerable plasticity and are opportunist predators, capturing the most abundant or vulnerable prey. In this study we describe the diet composition of Barn Owls in a locality where the type of vegetation (and the associated small fauna) changed drastically after succes- sive natural fires in the area. Our objective is to record any change in prey use before and after the fires to assess the impact of this disturbance on the owls’ feeding be- havior. Methods The study site was located in northwestern Patagonia (41°03'S, 70°59'-71°00'W, 900 m above sea level). The area is a transition between the arid Patagonian steppe to the east and the humid Nothofagus forests to the west. The area is mountainous with rocky outcrops (with caves used by owls for roosting), and the vegetation is domi- ^ E-mail address: strix@bariloche.com.ar nated by bunchgrasses {Stipa speciosa), cushion bushes {Mulinum spinossum), and scattered bushes {Fabiana im- bricata, Discaria articulata, Maytenus chubutensis, and Ber- beris buxifolia) . At times, low trees {D. chacaye) form small- gallery forests. Mean annual temperature is 8°C, and mean annual rainfall is 800 mm (Paruelo et al. 1998). Diet of Barn Owls was studied from autumn-spring 1998 by analyzing pellets collected seasonally under two roosts (likely including 1-2 owl home ranges) . We divid- ed the yr into seasons: summer (December-Fehruary) , autumn (March-May) , winter (June-August) , and spring (September-November). In the Austral summer 1998- 1999, the area was affected by successive natural fires that destroyed most of the vegetation and left large patches of bare soil. The owls abandoned the known roosting sites, but did not leave the area. We continued collecting pellets in the summer and autumn 2000, after finding new roosts in an unburned area adjacent to the burned patches and not far from the abandoned roosting sites (ca. 300 m). Pellets were air dried and dissected using standard techniques (Marti 1987). Prey remains in pellets were identified using keys (Pearson 1995) and by comparison with reference collections. Mammalian prey were classi- fied to species and quantified by counting skulls and mandible pairs. Birds were identified to family level and quantified by counting skulls, while insects were classified to order and quantified by counting head capsules and mandibles. Biomass of each prey category in the total biomass of the diet was calculated by multiplying mean body mass of individuals by the number of individuals in pellets and expressed as a percent of total prey biomass consumed. June 2004 Short Communications 175 Geometric mean weight of prey (GMWP) in the diet was calculated following Marti (1987). Mean prey weights were taken from literature (Pearson 1983, Kramer et al. 1999), and from our own records. Mean weight of birds and coleopterans was taken from Donazar et al. (1997). Food-niche overlap (O) between diets in the pre- and post-fire periods was assessed by Pianka’s (1973) index: O = Xpiqi/ where p^ is the frequency of a prey type in 1998, and qi is the frequency of the same prey type in 2000. It ranges from 0 (no overlap)-! (com- plete overlap). To test for differences in frequencies of prey categories in the diet among seasons, and before and after fires, we used contingency tables analyzed using Gtests of independence (Zar 1996). We grouped less common prey species so <20% of the expected frequen- cies was <5. We attained that by lumping all species with an observed frequency >4. The criterion for statistical significance was P < 0.05. Results Our results revealed that Barn Owls fed largely on ro- dents (99.7% and 95.7% of the total prey items in 1998 and 2000, respectively), although they also consumed a small number of lagomorphs, birds (Emberizidae) and coleopterans (Table 1). The mean number of prey/pellet was 1.7 (SD = 0.8; range = 1-4; N = 221) in 1998 and 2.4 (SD = 1.3; range = 1-5; N = 58) in 2000 associated with a higher consumption of smaller-size prey (Table 1). There were significant differences in diet composition among seasons in 1998 (G = 36.3, df = 8, P < 0.05), maybe related to fluctuations in prey population abun- dance throughout the yr. However, we note that in 1998, Reithrodon auritus, Loxodontomys micropus, Abrothrix longipi- lis, and Oligoryzomys longicaudatus m^idc up 70-90% of to- tal number of prey in all seasons. We found no significant differences between the two seasons sampled in 2000 (G = 6.0, df = 2, P > 0.05). Consequently, we pooled data for further analysis. We found significant differences (G = 197.9, df = 5, P < 0.05) in diets between 1998 and 2000. Reithrodon auritus decreased, L. micropus and O. lon- gicaudatus almost disappeared, and Eligmodontia morgani showed a marked increase (from 3% in 1998 to >50% in 2000). Reithrodon auritus contributed most to the prey biomass in both yr, followed by L. micropus in 1998, and by E. morgani and Ctenomys haigi in 2000. Food-niche overlap between yr was 0.329. Geometric mean weight of prey was 44.0 g in 1998, and 24.7 g in 2000, indicating that much lighter prey were consumed in the later yr (Table 1 ) . Discussion Prey composition in the owls’ diet that we observed may have reflected changes in the small mammal fauna as a response to vegetational changes associated with fire. In 1998, the diet of Barn Owls was quite similar to that found in another site of similar characteristics (40°47'S, 7l°07'W; Pillado and Trejo 2000). Both sites present a mixed small mammal fauna of forest and steppe-adapted species (Pearson and Pearson 1982). In this type of hab- itat, green-grass eaters (P. auritus) predominated in open areas, while scansorial species (O. longicaudatus and L. micropus) were associated with bushes, and also some wide-ranging species as A. longipilis were found (Pearson 1995, Guthmann et al. 1997, Lozada et al. 2000). In our study site, removal of vegetation by fire created a large patch of open habitat. This produced a decrease in spe- cies richness associated with reductions in vegetational complexity, and increases in the abundance of species suited to exploit open habitats (Ojeda 1989). Ojeda (1989) compared unburned and burned sites in the Monte desert of Argentina, and found that E. typus (closely related to E. morgani; Kelt et al. 1991) was more abundant in the burned sites (characterized by a low- vegetational cover) than in the unburned sites. He con- cluded that E. typus increased numbers in burned areas due to its general morphological and physiological ad- aptations to xeric existence in open habitats. Eligmodontia morgani is a small mouse commonly caught by aerial predators in open habitats (Pearson et al. 1987) , a habitat association which may increase its risk of predation (Ko- tler 1984). Due to its small size, this species would be consumed by owls in absence of other energetically more profitable prey (Jaksic and Marti 1984). N. Guthmann (pers. comm.) live-trapped small mammals in burned and unburned areas shortly after the completion of our study (March 2001). Trapping in the burned site yielded more than 60% E. morgani by frequency of occurrence, followed by R. auritus (another open-habitat mouse; Pear- son 1988). The decrease of L. micropus and O. longicaudatus in the diet, rodents associated with bushy habitats (Pearson 1983), was probably also associated with the fires, which removed almost all vegetation. Abrothrix longipilis maintained a similar proportion in the diet before and after the fires. This is a species as- sociated with some vegetation cover (Pearson 1983), al- though can be found almost in all habitats from forests to arid zones. This flexibility in its habitat use probably enabled this species to survive after a severe transfor- mation of the vegetation. Although the number of pellets found in 2000 was not very large, the marked changes observed in the diet of Barn Owls after fire presumably show opportunistic be- havior by this species. Instead of switching hunting area, to pursue a specific prey. Barn Owls shifted the diet as the prey community adjusted to vegetation changes. As other authors have observed (e.g., Bose and Guidah 2001), the Barn Owl diet seems to reflect changes in the composition of the small mammal community, which are their main prey. Resumen. — Se estudio la dieta de la lechuza de campan- ario {Tyto alba) durante dos periodos de tiempo en un area montanosa semi-arida del noroeste de la Patagonia argentina. Los periodos analizados fueron antes (1998) y despues (2000) de que el area fuera afectada por in- Table 1. Percent frequency (Freq) and percent biomass (Bio) of food items found in pellets of Barn Owls in northwestern Argentine Patagonia before (1998) and after (2000) the area was burned by fires (1999). 176 Short Communications VoL. 38 , No. 2 o o o (>1 00 O) CT) Q u hJ o o Ph CLi Q W hJ O O PL, PL, o 2 H 2 W S ^ Ph H § U Ph P P <: Ph O hH PQ a o I— I pp a Ph O I— ( PQ a Pm O PQ a J i-H GO CO 1 00 CM no 1 q GO oo q CM GO 1 1 i nH GO IT) 1 d CO d 1 GO d d d i-H rP d 1 1 o p2 bJD c/3 PM GO 05 q oo 1 ^ 1 1 1 ^ q t-H 1-H I T GM d rP GM d 1 i> 1 1 hH 1 hH CM 00 d I CO d t-H CM CM 00 T GO j> 1 1 1 ^ 1 ^ q q oo I T 05 d d d d 1 CM 1 1 d 1 CM d i6 I I-H CM lO cq iq i> on J> hh d CM CO iq to GM d I I H I q I t-H q GO I I oo I I I d. CO d (X> GO CM iq c£> d CO uo o -5^^ d 00 ^ q l-H CO q rP CM 00 CM GM q ori GM So * 'Jn ^ ’ll 1 1 p ill H <3 S OS e P o ^ J!£ .JS 3 ' S o o s g^ s f S ^ c\\ H5 HI s^ O q q q tj <3 s - s tq tq s V- § "o .S I — I q ^ Hi <3 OS S S -2 S' o M .§0 I ■S' s 3 d ?S e S o ■os S • ?»s P o X) o Mh X o cP ■ ^ •1^ p ■u 03 ■ P CM Xl PM u O a o he ri q f ip] QO 00 CO lO liO I ^ 05 CM CO I I d GO I d d I-H I-H I I X cO i-H CO GM I 00 ^ I I ^ I I ® I t-H e- 1-H ^ 1 1 I rP iri I I ^ I I GO I gm d CM d 2 ' ' CM ^H CM GM 05 GO 1 CM 1 1 1 1 1 1 05 05 ®9 III 1 irj ^ 1 1 1 1 1 rP 1 hH CM 00 GO III GO ^H 00 00 m 1 "a lO GO GO CM CM 00 1 ®9 III 1 o t-H t-H d d d t-H 1 CO J> III O lO CD CM 1 — ( iO GO GO 1 CM 00 1 CM 00 1 GO ID 1 1 1 I-H d d 1 d d d 1 d d CO 1 d GO 1 1 1 I-H CM 00 CM GO q q ao q q CM q f-H q 00 GO q q o d> tp lb lb d rP d I-H d I-H d tP GO GO in d CM CM t-H I-H «P I-H 00 no CM CM no CO rh GO j> X !h ffl M) O o' Ph a M o g CM PM 23 ’cS rv HJ HJ I ^ ^ 3 U June 2004 Short Communications 177 cendios naturales sucesivos que destruyeron la vegetacion casi completamente. En ambos periodos los roedores re- presentaron mas del 95% de las presas consumidas. Sin embargo, se observe un gran cambio en la composicion de las mismas. En 1998, Reithrodon auritus, y otros roe- dores sigmodontinos asociados a ambientes arbustivos fu- eron los mas consumidos. En 2000, Eligmodontia morgani, especie tipica de microhabitats abiertos con suelo des- nudo, represento mas del 50% de la dieta, y las especies asociadas a arbustos casi desaparecieron. Nuestros resul- tados indicaron que E alba fue un predador oportunista al alimentarse de pequenos mamiferos, y muy sensible a las modificaciones en la abundancia de las presas. [Traduccion de los autores] Acknowledgments We thank Otto Bitterman for letting us work in Estan- cia San Ramon. We also thank Diego Anon Suarez for insect identification, and Ulyses Pardinas for his com- ments. We are also grateful to M.I. Bellocq, C. Marti, and J. Vargas for their valuable comments that greatly im- proved this manuscript. Literature Cited Bose, M. and F. Guidali. 2001. Seasonal and geographic differences in the diet of the Barn Owl in an agro- ecosystem in northern Italy. /. Raptor Res. 35:240-246. Canevari, M.P., P. Canevari, G.R. Carrizo, G. Harris, J. Rodriguez Mata, and RJ. Straneck. 1991. Nueva guia de las aves argentinas. Fundacion Acindar, Buen- os Aires, Argentina. Donazar, J.A., A. Travaini, O. Ceballos, O.M. Delibes, and F. Hiraldo. 1997. Food habits of the Great Horned Owl in northwestern Argentine Patagonia: the role of introduced lagomorphs. /. Raptor Res. 31: 364-369. Guthmann, N., M. Lozada, J.A. Monjeau, and K.M. Hei- nemann. 1997. Population dynamics of five sigmodon- tine rodents of northwestern Patagonia. Acta Theriol. 42:143-152. Jaksic, F. and C.D. Marti. 1984. Comparative food habits of Bubo owls in Mediterranean-type ecosystems. Condor 86:288-296. Kelt, D.A., R.E. Palma, M.H. Gallardo, and J.A. Cook. 1991. Chromosomal rmAxXiormitg \n Eligmodontia (Mu- ridae, Sigmodontine) , and verification of the status of E. morgani. Z. Saeugetierkunde 56:352—358. Kotler, B.P. 1984. Risk of predation and the structure of desert rodent communities. Ecology 65:689—701. Kramer, K.M., J.A. Monjeau, E.C. Birney, and R.S. Sikes. 1999. Phyllotis xanthopygus. Mammal. Sp. 617:1-7. Lozada, M., N. Guthmann, and N. Baccala. 2000. Mi- crohabitat selection of five sigmodontine rodents in a forest-steppe transition zone in northwestern Pata- gonia. Reithrodon. Stud. Neotrop. Fauna Environ. 35:85— 90. Marti, C.D. 1987. Raptor food habits studies. Pages 67— 80 in B.A.G. Pendleton, B.A. Millsap, K.W. Cline, and D.M. Bird [Eds.], Raptor management techniques manual. Sci. Tech. Ser. 10. Nat. Wildl. Fed., Washing- ton DC, U.S.A. Ojeda, R.A. 1989. Small-mammal responses to fire in the Monte Desert, Argentina./. Mammal, 70:416-420. Paruelo, J.M., A. Beltran, E. Jobbagy, O.E. Sala, and R.A. Golluscio. 1998. The climate of Patagonia: gen- eral patterns and controls on biotic processes. Ecol Austral. 8:85-101. Pearson, O.P. 1983. Characteristics of a mammalian fau- na from forests in Patagonia, southern Argentina. J. Mammal. 64:476-492. . 1988. Biology and feeding dynamics of a South American herbivorous rodent. Reithrodon. Stud. Fauna Neotrop. Environ. 23:25—39. . 1995. Annotated keys for identifying small mam- mals living in or near Nahuel Huapi National Park or Lanin National Park, southern Argentina. Mastozool. Neotrop. 2:99-148. AND A.K. Pearson. 1982. Ecology and biogeogra- phy of the southern rainforests of Argentina. Pages 129—144 in A.M. Mares and H.H. Genoways [Eds.], Mammalian biology in South America, Spec. Publ Ser. 6. Pymatuning Lab. Ecol. Univ. of Pittsburgh, Linesville, PA U.S.A. , S. Martin, and J. Bellati. 1987. Demography and reproduction of the silky desert mouse {Eligmo- dontia) in Argentina. Fieldiana Zool. 39:413-431. PlANKA, E.R. 1973. The structure of lizard communities. Ann. Rev. Ecol. Syst. 4:53-74. PIIIADO, M.S. AND A. Trejo. 2000. Diet of the Barn Owl {Tyto alba tuidara) in northwestern Argentine Pata- gonia./. Raptor Res. 34:334—338. Travaini, A., J.A. DonAzar, O. Ceballos, A. RoDniGUEZ, F Hiraldo, and M, Delibes. 1997. Food habits of common Barn Owls along an elevational gradient m Andean Argentine Patagonia./. Raptor Res. 31:59-64. Zar, J.H. 1996. Biostatistical analysis. Prentice Hall, Up- per Saddle River, NJ U.S.A. Received 13 September 2002; accepted 28 February 2004 178 Short Communications VoL. 38, No. 2 J Raptor Res. 38{2):178-181 © 2004 The Raptor Research Foundation, Inc. Trophic Relationships Between White-tailed Kites {Elanus leucurus) and Barn Owls ( Tyto alba) in Southern Buenos Aires Province, Argentina Lucas M. Leveau^ and Carlos M. Leveau Alte. Brown 2420, 1° A, 7600 Mar del Plata, Argentina Closes F.J. Pardinas Centro Nacional Patagonico, Casilla de Correo 128, 9120 Puerto Madryn, Argentina Key Words: Barn Owl, Tyto alba; White-tailed Kite, Elanus leucurus; diet, competition', trophic overlap. Similar species often partition resources along three di- mensions: the habitat used for foraging, the kind of food eaten, and the time of day that foraging occurs (Cody 1968, Schoener 1974a, 1974b, Jaksic 1988). Time is con- sidered to be the least important in niche partitioning (Schoener 1974a, 1974b). Moreover, Jaksic (1982) argued that time of activity was not adequate to separate niches of hawks and owls. On the other hand, Marti and Kochert (1995) studied the similarity in the diets of two generalistic raptors. Red-tailed Hawks {Buteo jamaicensis) and Great Horned Owls {Bubo virginianus) , concluding that time of activity resulted in diet differences sufficient to separate the niches of these two raptors. The diet of the Barn Owl ( Tyto alba) has been studied intensively in some regions of Argentina (Bellocq 2000, Pardinas and Cirignoli 2002). The White-tailed Kite {Elanus leucurus), on the other hand, is poorly known, and its biology in South America has been addressed by only a few contributions (e.g., Meserve 1977, Schlatter et al. 1980, Leveau et al. 2002). White-tailed Kites are mainly diurnal, although also have been reported to be crepuscular (Jaksic et al. 1987, Mendelsohn and Jaksic 1989); Barn Owls are mostly noc- turnal, but occasionally hunt during the day (del Hoyo et al. 1999). These two raptors, common in the Buenos Aires province (Narosky and Di Giacomo 1993), are well- known rodent predators (>90% of prey in most studies; Mendelsohn and Jaksic 1989, Bellocq 2000). Both species occupy similar habitat in sympatry (Narosky and Yzurieta 1987, Narosky and Di Giacomo 1993). Additionally, their body masses are very similar (White-tailed Kite x = 302.2 g and Barn Owl x = 307 g; Schlatter et al. 1980, Jaksic et al. 1992, respectively). Therefore, the period of hunt- ing activity may be a key factor separating the niches of these two species. Here, we compare the small mammals consumed by White-tailed Kites and Barn Owls in a southern Buenos Aires area, Argentina, and examine the degree of dietary similarity to evaluate if activity periods separate niches of these species. ^ E-mail address: lucasleveau@yahoo.com.ar Methods We collected data in Villa Cacique (37°40'S, 59°23'W; 210 m elevation), Benito Juarez county, Buenos Aires province, Argentina. This region is dominated by agro- ecosystems and introduced woodlands. The original veg- etation (herbaceous steppe) has been reduced to small remnant patches in areas where agriculture is not feasi- ble. The weather is temperate, with an annual mean tem- perature of 13.3°C and annual mean precipitation of 775 mm, concentrated during the summer (Jaureguy and Bernabe 1987). We collected 77 fresh pellets and the remains of one prey from three pairs of White-tailed Kites. For Barn Owls, we examined 154 fresh pellets from two pairs. Both samples were collected under nests and roost sites from August-December 1998. Minimum number of prey were determined by skull remains in pellets and identified by comparison with reference material of Museo de La Plata mammal collections. Biomass of prey were estimated by multiplying the number of individuals of each prey spe- cies by the mean mass of these prey obtained from lit- erature (Redford and Eisenberg 1992). To compare tro- phic resources between both raptors, we estimated a standardized niche breadth (Jaksic 2000). This index varies between 0 and 1, and permits comparison between species. Additionally, we used Pianka’s index (Marti 1987) to measure trophic overlap. Values of this index vary between 0 (no overlap) and 1 (complete overlap). Finally, we estimated geometric mean prey mass (Marti 1987). This estimation is useful in the comparison of di- ets among raptors (Marti 1987). To examine activity period and its relationship with prey consumption, we classified prey and prey percent biomass based on pellet data as available during nocturnal, diurnal, or both periods, based on literature (e.g., Dalby 1975, Mas- soia 1976, Pearson 1988, Nowak 1999, Pardinas unpubl. data). We used a chi-squared test to compare the relative proportion of prey in the different periods of activity be- tween species. Geometric mean prey mass was compared among raptors using a t-test, after log-transformation to normalize the data (Sokal and Rohlf 1981). We acknowledge that determination of raptor diets with the analysis of pellets, especially for kites, involves some inherent biases. Specifically, Falconiforms typically digest bone to a greater extent than do owls (Marti 1987, Andrews 1990). Here we offer a preliminary comparison of the diets of these two raptors in the southern Buenos Aires province. We also suggest that additional data should be collected to evaluate the biases of using pellets June 2004 Short Communications 179 Table 1. Percent frequency and biomass of small mammals consumed by White-tailed Kite (N = 109 prey) and Barn Owl (A^ = 448 prey) in Villa Cacique, Buenos Aires, Argentina. Prey Prey Mass White-tailed Kite Barn Owl Percent Frequency Percent Biomass Percent Frequency Percent Biomass Calomys sp. 14 24.8 11.0 57.1 23.6 Akodon azarae 28 37.6 33.4 25.4 21.0 Oxymycterus rufus 76 8.3 19.9 3.3 7.5 Oligoryzomys flavescens 19 5.5 3.3 4.0 2.2 Holochilus brasiliensis 326 0.0 0.0 2.2 21.4 Reithrodon auritus 79.5 0.0 0.0 2.9 6.8 Necromys benefactus 31 14.7 14.4 1.6 1.4 Mus domesticus 14 0.9 0.4 1.1 0.5 Rattus sp. 320 0.0 0.0 1.1 10.5 Cavia aperea (juvenile) 250 1.8 14.5 0.7 4.9 Monodelphis dimidiata 15 6.4 3.1 0.2 0.1 Chiroptera 11 0.0 0.0 0.2 0.1 100.0 100.0 100.0 100.0 ^From Redford and Eisenberg (1992). to assess the diet of White-tailed Kites relative to using this technique for Barn Owls. Results and Discussion For White-tailed Kites, seven taxa of cricetid rodents accounted for more than 90% of 109 individuals con- sumed, followed by the marsupial {Monodelphis dimidiata\ 6.4%; Table 1). The most common species taken were Akodon azarae, Calomys sp., and Necromys benefactus (Table 1). Prey mass varied between 14 g {Calomys sp., Mus do- mesticus) and 250 g {Cavia juvenile; Table 1). Ako- don azarae, Oxymycterus rufus, C. aperea, and JV. benefactus, in that order, accounted for 82% of the biomass of prey (Table 1). For Barn Owls, 10 taxa of cricetid rodents were iden- tified from the 448 individuals consumed. Monodelphis dimidiata and an unidentified bat were also recorded (Ta- ble 1). The most commonly taken species were Calomys sp. and A. azarae, representing more than 80% of the prey consumed (Table 1). Prey mass varied between 11 g (Chiroptera) and 326 g {Holochilus brasiliensis; Table 1). Calomys sp., A. azarae, and H. brasiliensis accounted for 66% of the biomass of prey, in that order of importance (Table 1). Standardized niche breadths were 0.45 and 0.14 for White-tailed Kites and Barn Owls, respectively. The great- er breadth for White-tailed Kites was due to the inclusion of A. azarae, Calomys sp., and N. benefactus, while Barn Owls preyed mainly on Calomys sp. (Table 1). Pianka’s index was 0.80, indicating a substantial tro- phic overlap between the two raptors. Simeone (1995), who studied the diet of White-tailed Kites and Barn Owls in Chile, also found overlap values ranging from 0.87- 0.96. In our study, the high trophic overlap might be related to several factors acting singly or in combination. (1) both raptors share the same hunting habitats, mainly harvested wheat fields and pasture fields (L. Leveau and C. Leveau unpubl. data); (2) the prey resources (small mammals) may be very abundant and, therefore, easily available to both raptors; and (3) these resources (small mammals) are available both during the day and night, the activity periods of hawks and owls, respectively. Ac- cording to Jaksic (1982), diurnal and nocturnal raptors could share the same trophic resources by extending their hunting activities to crepuscular hr, “sharing” the prey of that activity period. Prey frequencies and percent of prey biomass differed significantly in relation to period of activity (Fig. 1; = 135.15 and 133.27, respectively; df = 2; P < 0.001). White-tailed Kites consumed a larger proportion of di- urnal mammals, such as M. dimidiata, N. benefactus, and O. rufus (Fig. la). On other hand. Barn Owls consumed more rodents that were exclusively nocturnal, such as Calomys sp., H. brasiliensis, and R. auritus (Fig. la). Prey biomass showed a similar trend (Fig. lb). Geometric mean of prey body mass for White-tailed Kites (25.27 ± 3.26 g) was greater than that of Barn Owls (21.57 ± 2.8 g; t = 2.15, df = 555, P = 0.032). White- tailed Kites ate rodents that were heavier {N. benefactus 31 g and O. rufus 76 g), than the most frequent prey taken by Barn Owls {Calomys sp. 14 g; Table 1). While both raptors have almost the same body mass, White- tailed Kite seemed to be more effective at capturing larg- er rodents or, alternatively, prey such as N. benefactus and O. rufus could be more abundant during the day. Oxy- mycterus rufus shows peaks of activity between 0800—1000 H and 1400-1900 H in southern Buenos Aires province 180 Short Communications VoL. 38, No. 2 NOCTURNAL aURNOL BOTH Figure 1. Distribution of prey frequency (a) and prey biomass (b) based on activity periods of rodents con- sumed by White-tailed Kites and Barn Owls in Villa Ca- cique. (U. Pardihas unpubl. data). This pattern of diurnal ac- tivity could explain the low abundance of this species in several analyses of the Barn Owl diet (Pardinas 1999). Although both raptors will select their prey in accor- dance to their period of activity, a trophic overlap of 80% suggests potential competition for food when in short sup- ply (Simeone 1995). If prey were in ample supply, then the large trophic overlap may be interpreted as opportu- nistic convergence on abundant resources. However, the diurnal hunting activity of White-tailed Kites and the noc- turnal activity of Barn Owls probably results in the avoid- ance of interference interactions (Case and Gilpin 1974, Marti and Kochert 1995, Simeone 1995). Similarly, White- tailed Kites nest in trees (de la Pena 1992), while Barn Owls nest mainly in cavities of buildings (de la Pena 1994), m this way avoiding competition for nest sites. The dietary similarity of these two species in the southern part of the Buenos Aires province might indicate that both raptors are dietary counterparts, consuming the same trophic resourc- es alternatively during the day and night (Jaksic et al. 1981, Jaksic 1983, Simeone 1995). Resumen. — Se compararon los mamiferos ingeridos por dos conocidos especialistas en el consumo de roedores, el milano bianco {Elanus leucurus) y la lechuza de cam- panario {Tyto alba), en el sur de la provincia de Buenos Aires, Argentina. Ambas rapaces depredaron casi exclu- sivamente sobre roedores cricetidos. Los valores de am- phtud de nicho trofico estandarizado para el milano bianco y la lechuza de campanario fueron de 0.45 y 0.14, respectivamente. El solapamiento trofico entre las dos ra- paces, basado en el indice de Pianka, fue del 80%. Los roedores de actividad diurna fueron mas frecuentes y aportaron mayor biomasa en la dieta del milano bianco. El mismo patron fue observado en la dieta de la lechuza de campanario, pero en relacion con roedores funda- mentalmente nocturnos. El peso promedio de las presas fue significativamente mayor en la dieta del milano que en la de la lechuza. El alto grado de solapamiento trofico podria estar indicando potencial competencia entre las dos especies. [Traduccion de los autores] Acknowledgments P. Timo, J. Valero, D. Retondo, A. Leveau, C. Leveau, and R. Schlatter helped in many ways. M.I. Bellocq and F. Jaksic, three anonymous referees, and the editor gave critical comments on the manuscript. We really appreci- ate the improvements in English usage made by James Roper through the Association of Field Ornithologists’ program of editorial assistance. This research was sup- ported by a scholarship from the Fundacion Antorchas (LML and CML) and funds from the Consejo Nacional de Investigaciones Cientificas y Tecnicas (UIJP). Literature Cited Andrews, P. 1990. Owls, caves, and fossils. Predation, preservation, and accumulation of small mammal bones in caves, with an analysis of the Pleistocene Cave faunas from Westbury-sub-Mendip, Somerset, U.K. Univ. of Chicago Press, Chicago, IL U.S.A. Bellocq, M.I. 2000. A review of the trophic ecology of the Barn Owl in Argentina./. Raptor Res. 34:108—119. Case, T.J. and M.E. Gilpin. 1974. Interference competi- tion and niche theory. Proc. Nat. Acad. Sci. 71:3073— 3077. Cody, M.L. 1968. On the methods of resource division in grassland birds communities. Am. Nat. 102:107-147. Dalby, P.L. 1975. Biology of Pampa rodents, Balcarce Area, Argentina. Publ. Mus. Mich. State Univ. Biol. Ser. 5:149- 272. DE La Pena, M.R. 1992. Guia de aves argentinas. Tomo 2, Falconiformes, Galliformes, Gruiformes, Charadri- formes. Edicion L.O.L.A., Buenos Aires, Argentina. . 1994. Guia de aves argentinas. Tomo 3, Colum- biformes, Psittaciformes, Cuculiformes, Strigiformes, Caprimulgiformes, Apodiformes, Trogoniformes, Coraciformes, Piciformes. Editorial L.O.L.A., Buenos Aires, Argentina. DEL Hoyo, J., A. Elliott, and J. Sargatal (Eds.). 1999. Handbook of birds of the world. Vol. 5: Barn Owls to Hummingbirds. Lynx Edicions, Barcelona, Spain. Jaksic, F.M. 1982. Inadequacy of activity time as a niche difference: the case of diurnal and nocturnal raptors. Oecologia 52:171—175. . 1983. The trophic structure of sympatric assem- blages of diurnal and nocturnal birds of prey. Amer. Midi. Nat. 109:152-162. . 1988. Trophic structure of some Nearctic, Neo- tropical and Palearctic owl assemblages: potential roles of diet opportunism, interspecific interference and resource depression./. Raptor Res. 22:44-52. . 2000. Ecologia de comunidades. Ediciones Univ- erisdad Catolica de Chile, Santiago, Chile. June 2004 Short Communications 181 , H.W. Greene, and J.L. Yanez. 1981. The guild structure of a community of predatory vertebrates in Central Chile. Oecologia 49:21-28. , R. Rozzi, A. Iajbra, and J.E. Jimenez. 1987. 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Resource partitioning in ecolog- ical communities. Science 185:27-39. . 1974b. The compression hypothesis and tempo- ral resource partitioning. Proc. Nat. Acad. Sci. 71:4169- 4172. Simeone, A.C. 1995. Ecologia trofica del bailarin Elanus leucurus y la lechuza Tyto alba y su relacion con la in- tervencion humana en el sur de Chile. Tesis de Li- cenciatura, Universidad Austral de Chile, Valdivia, Chile. SOKAL, R.R. AND FJ. Rohlf. 1981. Biometry. Freeman, San Francisco, CA U.S.A. Received 6 May 2003; accepted 27 November 2003 J. Raptor Res. 38(2) :181-186 © 2004 The Raptor Research Foundation, Inc. Relative Abundance and Diversity of Winter Raptors in Spokane County, Eastern Washington Howard L. Ferguson^ Washington Department of Fish Wildlife, North 8702 Division Street, Spokane, WA 99218 U.S.A. Key Words: Red-tailed Hawk] Buteo jamaicensis; Rough- For years, biologists, falconers, and bird-watchers have legged Hawk] Buteo lagopus; relative abundance] roadside recognized the high density of raptors in eastern Wash- survey] sympatry] winter distribution. ington during the winter. Discussions with observers throughout the region indicate this zone of high abun- dance may extend from eastern Washington, east to the ^ E-mail address: ferguhlf@dfw.wa.gov 182 Short Communications VoL. 38, No. 2 Boise area, Idaho, and south into Utah. Underscoring the importance of identifying and quantifying this zone of potentially high raptor abundance is the rapid human population growth occurring in this same region. The mean growth rate in eastern Washington is 19.1%, with some counties recording growth rates of 35-36%. Boise, Idaho experienced a phenomenal growth rate of 46.1% (U.S. Census Bureau 2001). For effective land use plan- ning, quantitative biological data are required. Such data are also required to design and implement long-range, year-round, landscape-level raptor conservation strategies (Sherry and Holmes 1995). Local governments in east- ern Washington are just beginning to develop growth management policies in an attempt to preserve and pro- tect the native wildlife as the human population contin- ues to expand into formerly rural land and wildland. Data on the abundance and ecology of the local wildlife IS necessary to help establish these policies. In order to verify and quantify the high winter raptor densities in eastern Washington, a 3-yr study was conducted in east- ern Washington from 1995-98. Road counts were employed because one of the objec- tives of this study was to compare the results of this survey to other winter raptor studies in the western U.S. Al- though the reliability of road counts has been questioned (Millsap and LeFranc 1988) due to several inherent bi- ases (e.g., species detectability, perch availability, along roads, weather, variation in observer expertise) this ap- proach can be effective in assessing relative abundance and long-term trends over large areas, particularly in more open habitats (Millsap and LeFranc 1988, Province of British Columbia 2001, Hutto and Young 2002). In addition, recommended standardized guidelines were followed when conducting the surveys (e.g., Andersen et al 1985, Bildstein 1987, Fuller and Mosher 1987, Ander- sen and Rongstad 1989). Study Area The study was in Spokane County in eastern Washing- ton near the border of Idaho (Fig. 1). Spokane County has ca. 250 000 people in urban areas, and 200 000 in nonurban areas (Washington Office of Financial Man- agement 1998). Spokane County is dominated by Pon- derosa Pine {Pinus ponderosa) and Palouse (steppe) veg- etation zones (Cassidy 1997; Fig. 1). Much of the county consists of a transition zone ranging from the arid Co- lumbia Basin shrub-steppe region in the southwest cor- ner to the mixed evergreen forests of the Selkirk-Rocky Mountain complex in the northeast corner. Methods I conducted 120 roadside surveys on five different routes (24 surveys of each route) for three consecutive winters covering ca. 2510 km of secondary roads. These five routes were located on secondary roads outside the city of Spokane that had low traffic volumes, sufficient shoulder width for stopping, and scheduled snow remov- al (Fig. 1). The lengths of the five survey routes were 28.9, 27.3, 22.5, 12.1, and 13.7 km for Big Meadows (BM), Coulee Hite (CH), Hangman Valley (HV), Little Spokane (LS) and Saltese Flats (SF) routes, respectively. Three of the routes (BM, CH, HV) traversed multiple habitats including agricultural, mixed evergreen forests dominated by ponderosa pine, and riparian areas. The LS route followed a riparian corridor containing a mix of cottonwood {Populus balsamifera) , Douglas-fir {Pseudot- suga rnenziesii) and ponderosa pine. The SF route includ- ed lowland with emergent wetlands surrounded by pon- derosa pine, native bunchgrass steppe, and some agriculture. Each of the five routes was surveyed six times during the winter of 1995-96 and 9 times each of the 2 subsequent winters, 1996-97 and 1997—98. The routes were sampled starting 15 November ending 15 March. The direction and order in which transects were driven were varied and conducted throughout the day to mini- mize temporal biases. All surveys were conducted be- tween 0800-1600 H at vehicle speeds of 40 km/hr or less. Occasional brief stops (<2 min) were made to identify and to record observed raptors. Surveys were not con- ducted, if weather conditions resulted in restricted vision or if winds were >40 km/hr. Only raptors initially seen with the unaided eye were recorded. Binoculars (10 X 40 and 8 X 42) were used to aid in identification. Both perched and flying raptors were recorded and mapped, including direction of flight. After first detection, all attempts were made to minimize recounting of raptors by noting previous observations, direction of flight, mapped location, and any comments such as an unusual color phase. Subsequently, if a bird of the same species, phase, age, and sex was observed in the same area as a previously recorded bird, this obser- vation was not recorded. Because of the small sample size obtained for less com- mon species, most of the results were restricted to the five most common species. Unknown raptors were elim- inated from the study results {N = 7, <1%). To deter- mine if there were significant time-of-day influences on the number and species of raptors observed, data were categorized two different ways. The first method divided all observations into four time categories: 0800-0959, 1000-1159, 1200-1359, and 1400-1559 H. while the sec- ond divided observations into two time periods: morning from 0800-1159 H, and afternoon from 1200-1559 H. Chi-square tests (Sokal and Rohlf 1995) were used to look at the significance of these results. A correction for continuity was made for chi-square tests with only one degree of freedom. Ten winter raptor studies were selected from the lit- erature that allowed calculation of relative abundance (i.e., number of raptors observed and distance traveled were reported) and were used for comparison to this study (Table 1). All results and analyses were standard- ized to the distances surveyed. Relative abundance was calculated as the number of birds observed divided by the km surveyed times 1000. Results A total of 1205 raptors of 12 different species were re- corded. The four most common species were Red-tailed Hawk {Buteo jamaicmsis; 65%), Rough-legged Hawk {Buteo lagopus; 18%), Bald Eagle (Haliaeetus leucocephalus’, 6%), June 2004 Short Communications 183 Legend Survey Routei Big Heeulovs Coulee Hite ZXZZ3 Hftngiuan Valley ■M Little Spokane a^B Maltese Flats Veoetation Zones rp~n~\ ; j Ponderosa Pine rTTTTn rhree-tip Sage Douglas Fir [] J Grand Fir Figure 1. Map of Spokane County, WA, showing study area including raptor road count routes and major vegetation types, 1995-98. and Northern Harrier {Circus cyaneus; 5%; Table 1). Amer- ican Kestrel {Falco sparverius) comprised 3%, two other fal- cons, Merlin {F. colu?nbanus) and Prairie Falcon (F. mexi- canus) together added 0.5%, Golden Eagle (Aquila chrysaetos) less than 0.1%, and all three species of Accipi- ters, Sharp^hinned Hawk {Accipiter striatus). Cooper’s Hawk (A. cooperii), and Northern Goshawk (A. gentiUs) comprised an additional 1%. The Great-horned Owl {Bubo virginianus) made up 1%. The relative abundance of the predominant five species was 313 for Red-tailed Hawks, 88 for Rough-le^ed Hawks, 29 for Bald Eagles, 24 for North- ern Harriers, and 13 for American Kestrels. Relative abun- dance for the entire study was 480 raptors (Table 1). The 65 morning surveys covered ca. 1345 km while the 55 afternoon surveys covered 1165 km. I observed 41% of all raptors in the morning and 58% in the afternoon (Table 1). Significantly more raptors were observed in the afternoon than in the morning (x^ = 71.38, P < 0.001). Red-tailed Hawks, Rough-legged Hawks, and Northern Harriers were observed more frequently on af- ternoon surveys than on morning counts (x^ = 51.66, 12.78, and 29.78, respectively; all P < 0.001). Discussion In the Spokane area, I recorded relative abundance of 480 raptors/ 1000 km, a higher abundance than 10 pre- 184 Short Communications VoL. 38, No. 2 Table 1. Morning, afternoon, and total results of raptors observed and their relative abundance during winter in Spokane County, eastern Washington, 15 November-15 March, 1995—98. Birds Observed Mornings Afternoons Total No. Abundance® No. Abundance® No. Abundance® Red-tailed Hawk 320 237.9 466 400.0 786 313.1 Rough-legged Hawk 92 68.4 129 110.7 221 88.0 Bald Eagle 38 28.2 34 29.2 72 28.7 Northern Harrier 20 14.9 41 35.2 61 24.3 All other species combined 29 21.5 36 31.0 65 25.9 All species 499 371.0 706 606.0 1205 480.1 ® Relative abundance based on raptors recorded per 1000 km. vious studies in the western U.S.A. (Table 2). The study with the next highest relative abundance (432) is another Washington study conducted ca. 320 km west of Spokane in Kittitas County (Chestnut and Boomgarden 1997). When evaluated on a landscape level, these two studies suggest high winter raptor abundance throughout the eastern Washington area. The next highest relative abun- dance values reported were 350 in central Utah (Fischer et al. 1984), and 262 in northern Utah (Brouse 1999). With regard to species diversity, 12 species were observed during the 3-yr study, placing it second in reported rich- ness along with several of the other western studies (Ta- ble 2). Red-tailed Hawks had the highest relative abundance with 313, while Rough-legged Hawks were next highest with 88, a ratio of 3.6 Red-tailed Hawks for each Rough- legged Hawk. Chestnut and Boomgarden (1997) also re- ported Red-tailed Hawks (290) as the most common spe- cies with Rough-legged Hawks (108) being the second most common, a ratio of 2.7. These unusually high Red-tailed Hawk numbers differ from the other published studies in the more northern and eastern portions of the west. In Colorado and Ne- braska, Enderson (1965), Mathisen and Mathisen (1968), and Johnson and Enderson (1972) reported Rough-leg- ged Hawks as the most common Buteo on winter roadside counts while Red-tailed Hawks were scarce. Stahldecker and Belke (1974) observed only five Red-tailed Hawks, but observed 108 Rough-legged Hawks in northeastern Colorado. Similarly, Johnson and Enderson (1972) in eastern Colorado recorded only four red-tails, but 107 Rough-legged Hawks. In neighboring Idaho, Craig (1978) found Rough-legged Hawks to be the most nu- merous wintering raptor, while Red-tailed Hawk numbers were so low they were not reported. On the other hand, studies in the southwestern U.S.A. indicate Red-tailed Hawks predominate. In southeastern Arizona, Parker and Campbell (1984) reported 200 red-tails and only 14 rough-legs. In central California, Smallwood et al. (1996) recorded 822 red-tails and only five Rough-legged Hawks. Table 2. Relative abundance and species diversity derived from published winter road count raptor studies in the western U.S.A. (some values were calculated from the publ. data). Location Relative Abundance (Raptors/ 1000 km) No. OF Species Totai. km Traveled This study Eastern WA 480.1 12 2510 Chestnut and Boomgarden (1997) Eastern WA 450.5 11 1445 Fischer et al. (1984) Central UT 350.0 10 1500 Brouse (1999) Northern UT 261.9 13 4070 Stahldecker and Belke (1974) Northeast CO 208.1 8 1312 Johnson and Enderson (1972) Eastern CO 173.5 9 1677 Marion and Ryder (1975) Northeast CA 166.7 6 936 Enderson (1965) Eastern CO 158.0 9 2695 Craig (1978) (Nov— Mar) Southeast ID 88.7 12 3553 Parker and Campbell (1984) Southeast AZ 80.5 12 6386 Andersen and Rongstad (1989) Southeast CO 71.6 12 3407 June 2004 Short Communications 185 In contrast to these other studies, my study reveals that eastern Washington has relatively high numbers of both Red-tailed and Rough-legged hawks (Table 1 ) . This sympatry of Red-tailed and Rough-legged hawks seems to be the unusual feature of the winter raptor pop- ulation in eastern Washington. I suggest that this zone of high relative abundance with these two species being sympatric extends south into Utah based on two Utah studies of wintering raptors. Brouse (1999) observed 161 red-tails and 55 Rough-legged Hawks, while Fischer et al. (1984) reported 169 red-tails and 78 Rough-legged Hawks, ratios of 2.9 and 2.2 red-tails to rough-legs, re- spectively. The relative abundance values found in these two studies for red-tails and Rough-legged Hawks were the highest reported next to the two Washington studies. However, more studies need to be conducted, particular- ly in Idaho, to determine the extent of this zone of sym- patry. Craig’s (1978) results in southeastern Idaho indi- cated that Red-tailed Hawks occurred only in low numbers in that region. In conclusion, eastern Washington is an important win- tering area for a large and diverse raptor community. Contributing to this overall abundance is the fact that both Red-tailed Hawks and Rough-legged Hawks are abundant in this area. Although many of these raptors may not nest in the area, they do reside in, and depend upon the area for life support for several months each year. Considering this dependence, it is important to pro- tect and conserve these important wintering areas. De- velopment of conservation strategies for this key winter- ing area for raptors is particularly important because of growing urban areas, such as Spokane, in this region. Resumen. — Un total de 120 estudios de rapaces al borde de la carretera fueron llevados a cabo en cinco diferentes rutas en el condado Spokane, al oriente de Washington, cubriendo un total de 2510 km de carreteras secundarias durante los inviernos de 1995-98. Cerca de 1200 aves rapaces de 12 especies diferentes fueron registradas dur- ante el periodo de 3 ahos. Las cuatro especies mas co- munes. El gavilan de cola roja (Buteo jamaicensis; 65% del Total), el gavilan de patas gruesas {Buteo lagopus; 18%), el aguila calva {Haliaeetus leucocephalus-, 6%), y el aguilu- cho norteho {Circus cyaneus', 5%), abarcaron casi el 95% de todas las rapaces vistas. La abundancia relativa para todo el estudio fue 480 rapaces por cada 1000 km mues- treados. Fueron observadas signihcativamente mas rapa- ces en la tarde que en la mahana. La comparacion de resultados con otros 10 estudios en el occidente indico que la abundancia relativa de rapaces invernantes en el oriente de Washington fue una de las mas altas reporta- das para el Oeste. Esta alta abundancia relativa, en parte, parece ser resultado de la simpatria entre los gavilanes de cola roja y los de patas gruesas en el area oriental de Washington. [Traduccion de Cesar Marquez] Acknowledgments I am grateful to Tom Owens for help with the figures, and to Matt Vander Haegen and Jim Watson for their reviews. I would like to thank L. Flake, R. Lehman, and an anonymous referee for providing their helpful com- ments on earlier drafts of this manuscript. Literature Cited Andersen, D.E., OJ. Rongstad, and W.R. Mytton. 1985. Line transect analysis of raptor abundance along roads. Wildl. Soc. Bull. 13:533-539. and O.J. Rongstad. 1989. Surveys for wintering birds of prey in southeastern Colorado 1983-88 J Raptor Res. 23:152-156. Bildstein, K.L. 1987. Behavioral ecology of Red-tailed Hawks {Buteo jamaicensis) , Rough-legged Hawks {Buteo lagopus). Northern Harriers {Circus cyaneus), and American Kestrels {Falco sparverius) in south-central Ohio. Ohio Biol. Surv. Biol. Columbus, OH U.S.A. Brouse, P. 1999. Twenty year change in the raptor com- munity in northern Utah during the nonbreedmg season./. Raptor Res. 33:317-322. Cassidy, K.M. 1997. Land cover of Washington State: de- scription and management. Pages 1-260 in K.M. Cas- sidy, C.E. Grue, M.R. Smith, and K.M. Dvornich [Eds.], Washington State Gap Analysis. Washington Cooperative Eish and Wildlife Research Unit, Univer Washington, Seattle, WA U.S.A. Chestnut, T. and K. Boomgarden. 1997. Abundance, distribution, and habitat associations of raptors win- tering in the Kittitas Valley, Kittitas County, Washing- ton. Poster Presentation, Joint Meeting of Society for Northwestern Vertebrate Biology and The Wildlife So- ciety, Yakima, WA U.S.A. Craig, T.H. 1978. A roadside raptor survey of raptors m southeastern Idaho 1974-76. Raptor Res. 12:40-45. Enderson, J.H. 1965. Roadside raptor count in Colorado. Wilson Bull. 77:82-83. Fischer, D.L., K.L. Ellis, and RJ. Meese. 1984. Winter habitat selection of diurnal raptors in central Utah. Raptor Res. 18:98-102. Fuller, M.R. and J.A. Mosher. 1987. Raptor Survey Techniques. Pages 37-65 in B.A. Giron Pendleton, B.A. Millsap, K.W. Cline, and D.M. Bird [Eds.], Rap- tor Management Techniques Manual. Natl. Widl Fed., Washington, DC U.S.A. Hutto, R.L. and J.S. Young. 2002. Regional landbird monitoring: perspectives from the Northern Rocky Mountains. Wildl. Soc. Bull. 30:738-750. Johnson, D. and J.H. Enderson. 1972. Roadside raptor census in Colorado-winter 1971-72. Wilson Bull. 84: 489-490. Marion, W.R. and A. Ryder. 1975. Perch-site preferences of four diurnal raptors in northeastern Colorado. Con- dor 77:350-352. Mathisen, J.E. and a. Mathisen. 1968. Species abun- 186 Short Communications VoL. 38, No. 2 dance of diurnal raptors in the panhandle of Nebras- ka. 'Wilson Bull. 80:479-486. Millsap, B.A. AND M.N. LeFranc, Jr. 1988. Road transect counts for raptors: how reliable are they? J. Raptor Res. 22:8-16. Parker, R.E. and E.G. Campbell. 1984. Habitat use by wintering birds of prey in southeastern Arizona. West. Birds 15:175-183. Province of British Columbia. 2001. Inventory Methods for Raptors. Standards for Components of British Co- lumbia’s Biodiversity No. 11. Ministry of Sustainable Resource Management Environment Inventory Branch for the Terrestrial Ecosystems Task Force Re- sources Inventory Committee. Victoria, BC Canada. Sherry, T.W. and R.T. Holmes. 1995. Summer versus win- ter limitation of populations: what are the issues, what is the evidence. Pages 85-120 mT.E. Martin and D.M. Finch [Eds.], Ecology and management of neotropi- cal migratory birds: a synthesis and review of the crit- ical issues. Oxford Univ. Press, Oxford, U.K. Smallwood, S.K., B.J. Nakamoto, and S. Ceng. 1996. As- sociation analysis of raptors on a farming landscape. Pages 177-190 in D. Bird, D. Varland, and J. Negro [Eds.], Raptors in human landscapes. Raptor Re- search Foundation, Academic Press, Ltd., San Diego, CA U.S.A. SoKAL, R.R. AND F.J. Rohlf. 1995. Biometry: the princi- ples and practice of statistics in biological research. W.H. Freeman and Company, New York, NY U.S.A. Stahldecker, D.W. AND T.E. Belke. 1974. Winter diurnal raptor populations of three habitat types in north- eastern Colorado. Colo. Field Ornithol. 20:6-17. U.S. Census Bureau. 2001. United States Census 2000. U.S. Department of Commerce Economics and Statis- tics Administration, http:/ /www.census.gov. Washington Office of Financiai. Management. 1998. Population trends. Washington Office of Financial Management, Olympia, WA U.S.A. Received 3 February 2003; accepted 10 December 2003 J Raptor Res. 38 (2): 186-1 89 © 2004 The Raptor Research Foundation, Inc. Nesting of the White-throated Hawk {Buteo albigula) in Deciduous Forests of Central Chile Eduardo F. Pavez^ and Christian Gonzalez Union de Ornitologos de Chile (UNORCH), Casilla 13183, Santiago 21, Chile Benito A. Gonzalez F Agronomia e Ingenieria Forestal, Pontificia Universidad Catolica de Chile, Vicuna Mackenna 4860 Santiago, Chile Cristian Saucedo Corporacion Nacional Forestal, Ogana 1 060, Coyhaique, Chile Sergio Aiaarado Estudios para la Conservacion y Manejo de la Vida Silvestre, Blanco Encalada 350, Chilian, Chile Juan P. Gabella and Alejandra Arnello Union de Ornitologos de Chile (UNORCH), Casilla 13183, Santiago 21, Chile Key Words: White-throated Hawk', Buteo albigula; central Chile', breeding; deciduous forests. The White-throated Hawk (Buteo albigula; Philippi 1899) is found throughout the Andes mountain range, from northwestern Venezuela through southern Chile and southwestern Argentina (Brown and Amadon 1968). In Chile, the species has been considered an all-year res- ^ E-mail address: eduardopavez@hotmail.com ident between the latitudes of 27° and 40°S (Goodall et al. 1957), a local migrant (Zalles and Bildstein 2000), or its residency status was unknown (Jaksic and Jimenez 1986). Pavez (2000) presented the first evidence of mi- gratory movements. He reported its presence in Chile only during the breeding season (i.e., between Septem- ber and April), inhabiting high-elevation Nothofagus ior- ests (Olrog 1979, Navas and Manghi 1991, Casas and Ge- lain 1995, Pavez 2000). Information on the species’ breeding biology is scant June 2004 Short Communications 187 Figure 1. Distribution map of White-throated Hawks {Buteo albigula) in South America (A) and the locations in central Chile where observations of this species were noted in this study (B): La Campana National Park (1), Cerro El Roble (2), and Altos de Cantillana (3). (del Hoyo et al. 1994). According to de la Pena (1992), the White-throated Hawk nests in trees, laying two to three eggs. Recent data have been provided on two nest- ing pairs in a lenga forest {Nothofagus pumilio) by Trejo et al. (2001) and on a larger sample of breeding White- throated Hawks in northwest Argentinean Patagonia, 900 km south of central Chile, by Trejo et al. (2004) . In Chile, only one documented breeding record exists, corre- sponding to a nest on a coastal cliff near Tongoy, in north central Chile (30°25'S, 7l°50'W; Goodall et al. 1957). This is the northernmost nesting site recorded for the species. In order to contribute to our knowledge of this rare and poorly-known neotropical raptor, we present in- formation on its nesting and breeding behavior in central Chile. A pair of White-throated Hawks, which we presumed to be the same individuals, was observed over three con- secutive breeding seasons. In spring (4 October 1998), we found an occupied White-throated Hawk nest at La Campana National Park (32°58'S, 71°07'W, 300-1900 m above sea level) on the coastal chain of mountains in central Chile (Fig. 1). The nest site was located at an altitude of 1200 m, on a south facing slope in a native forest dominated by southern beech (roble) trees {Noth- ofagus macrocarpa) . The nest, which was nearly 1-m in di- ameter, was found on the top of a 25 m tall evergreen peumo tree {Cryptocarya alba) and located 50 m away from a secondary park road. As reported by Gelain et al. (2001), tourism and cars did not seem to affect the nest- ing behavior of this pair. The nesting pair reared one chick that left the nest in summer (January 1999). The nest was reused the follow- ing spring (October 1999) and the birds reared another chick, which again fledged in summer (January 2000). Also, on 6 October 2000 we observed a pair flying around the same nest, and a juvenile White-throated Hawk was recorded flying over the breeding territory near that nest on 11 March 2001. Plumage color of that juvenile was similar to the 2.5-mo-old dead bird described by Ojeda et al. (2003). Deliveries of materials to the nest and courtship flights with constant vocalizations were observed during the pre- laying period (15 hr of observations). Two copulations were recorded in spring (2 October 1999 and 6 October 2000). Six prey deliveries to the nest by the male were witnessed during the brood-rearing period (21 hr of ob- servation). Two reptiles (a Ghilean racerunner \Callop- istes palluma] and a lemniscated lizard [Liolaemus lemnis- catus'\), three birds (an Austral Thrush [Turdus falcklandit\ , and what appeared to be one Fire-eyed Diu- con [Xolmis pyrope] , and one White-crested Elaenia \_Elaen- ia albiceps] ) , and an unidentified rodent were consumed by chicks. Although the forest floor under the nest was searched thoroughly, no prey remains nor pellets were found. A young hawk was recorded flying around the nest close to the adult female at the end of the summer (3 hr of observation on 11 March 2000). Adult White-throated Hawks were detected three times in the area during the breeding season. One of them, an adult male, flew ca. 300 m from the known nest, but the male of the pair did not show any aggressive display to- ward the “intruder.” This suggested that other pairs like- ly nested in the area. No hawks were recorded in the study area during the 188 Short Communications VoL. 38, No. 2 nonbreeding season (28 hr of observations between April and August 1999). This coincides with the findings of Pavez (2000) regarding the timing of the migratory movements (i.e., departure from the breeding territory in April) . Other records also help establish the dates of the breeding season in the coastal mountains of central Chile. An adult hawk was recorded in early spring (29 September 1997) perched in a well-developed forest on El Roble hill (32°59'S, 70°59'W), located 10-km southeast of La Campana hill. This observation corresponds to the earliest White-throated Hawk record for the breeding season in the area. A pair of White-throated Hawks that had established their territory in a roble-forest stand {Nothofagus macrocarpa) at an altitude of 1600-1850 m in the mountains of Loncha, in the area of Altos de Cantil- lana (34°06'S, 70°59'W) was recorded during October 2000. This site is part of the same coastal mountain range as La Campana, but is located ca. 125-km further south (Fig. 1). Our observations agree with Pavez (2000) and Trejo et al. (2001) in relation to the characteristics of the breed- ing habitat (i.e., Nothofagus forests in mountainous areas) . This, in addition to other records made in the El Roble hill area by J. Jimenez (pers. comm.), who observed a female displaying breeding behavior in Nothofagus macro- carpa forest, suggests that in central Chile the few native mountainous forest areas located in the coastal mountain range in La Campana and El Roble hills could be a pri- mary breeding area for this hawk. These habitats are lo- cated on the top of the coastal mountain range, between 33° and 34°S latitude, in a narrow and discontinuous north-south corridor ca. 125 km in length. Nevertheless, additional sampling in exotic forests would be necessary in order to know whether this hawk may also breed in disturbed habitat. Considering the known habitat and that cliff nesting by this species has not been confirmed, we believe that it is unlikely for White-throated Hawks to nest on coastal cliffs, such as was reported by Goodall et al (1957), at a site near Tongoy (30°20'S). Given the high rate of destruction of deciduous native forests of central Chile (Lara et al. 1995), the breeding habitat of the White-throated Hawk in its northern breeding range is threatened (Jaksic et al. 2001). Fur- thermore, this species is considered rare and deserves more conservation attention (Jaksic and Jimenez 1986). Special attention should be given to those protected ar- eas that have Nothofagus forest, which may be essential for successful breeding by this hawk. Also, the creation of new protected areas with suitable habitat in central Chile could have a positive impact. Our data revealed this hawk’s breeding phenology in central Chile. In September, the birds arrive, probably from the northern Andes (Pavez 2000), on their breed- ing territories and repair the nests. Copulation and laying occur in October and chick-rearing occurs from Novem- ber-January. After fledging, the juveniles remain with the parents in the breeding territory, and then disperse at the end of March and the beginning of April. Our data agree with Trejo et al. (2004) about the duration of each breeding stage in Chile, but the breeding period is slight- ly earlier than in Argentinean Patagonia. This sequence matches the breeding behavior described for other mi- gratory accipiters, including a short stay by the juvenile on the parents’ territory followed by the departure of adults and juveniles from the breeding territory on about the same date (Newton 1979). Resumen. — ^Aqui presentamos los resultados de observa- ciones sobre una pareja de aguilucho chico (Buteo albi- gula) durante tres periodos reproductivos sucesivos en Chile central. La pareja utilizo el mismo nido durante todo el estudio. El nido se ubico en un bosque dominado por robles {Nothofagus macrocarpa), en la ladera de un cerro a 1200 m de altitud, criando un polio por estacion reproductiva. La conducta reproductiva siguio un patron esperable para buteos. Se observe actividad de otros aguiluchos en el area. No se observe presencia de aguil- uchos fuera del periodo reproductivo, lo que se expli- caria por su caracter migratorio. Nuestras observaciones indican que los bosques de Nothofagus, son el habitat usa- do para la reproduccion de esta especie en Chile central [Traduccion de los autores] Acknowi.edgments We thank Cipriano Nunez and the rangers of the Chile’s Forest Service (Corporacion Nacional Forestal) from the Granizo office. La Campana National Park, who allowed us access to the study area. We thank Cristian Estades, Jaime Jimenez, Javier Simonetti, David Ellis, and anonymous reviewers for commenting on the manu- script. Jerry Laker and Ros Clubb for improving the En- glish version and Magdalena Bennett for drawing the map. Literature Cited Brown, L. and D. Amadon. 1968. Eagles, hawks and fal- cons of the World. Vol. I. McGraw Hill, New York, NY U.S.A. Casas, A. and M. Gelain. 1995. Nuevos datos acerca del estatus del aguilucho andino Buteo albigula en la Pa- tagonia Argentina. Hornero 14:40—42. de la Pena, M. 1992. Guia de las aves Argentinas. Tomo 11. Literature of Latin America, Buenos Aires, Argen- tina. DEL Hoyo, J., A. Elliott, and J. Sargatal (Eds.). 1994 Handbook of the birds of the world. Vol. 2. Lynx Ed- icions, Barcelona, Spain. Gelain, M., V. Ojeda, A. Trejo, L. Sympson, G. Amigo, AND R. Vidal-Russell. 2001. Nuevos registros de dis- tribucion y nidificacion del aguilucho andino {Buteo albigula) en la Patagonia Argentina. Hornero 16:85-88. Goodall, J.D., A.W. Johnson, and R.A. Philippi. 1957. Las aves de Chile, su conocimiento y sus costumbres. June 2004 Short Communications 189 Tomo II. Platt Establecimientos Graficos, Buenos Ai- res, Argentina. Jaksic, F.M. and J.E. Jimenez. 1986. The conservation sta- tus of raptors in Chile. Birds of Prey Bull. 3:95-104. , E.F. Pavez, J.E. Jimenez, and J.C. Torres-Mura. 2001. The conservation status of raptors in the Met- ropolitan Region, Chile./. Raptor Res. 35:151-158. Lara, A., C. Donoso, and J.C. Aravena. 1995. La con- servacion del hosque nativo en Chile: prohlemas y de- safios. Pages 335-362 in]. Armesto, C. Villagran, and M.K. Arroyo [Eds.], Ecologia de los hosques nativos de Chile, Ed. Universitaria, Santiago, Chile. Navas, J. and M. Manghi. 1991. Notas sohre Buteo ven- tralis y Buteo albigula en la Patagonia Argentina (Aves, Accipitridae) . Rev. Mus. Argent. Cienc. Nat. Zool. 15:8'7- 94. Newton, I. 1979. Population ecology of raptors. T. & A.D. Poyser, London, U.K. Ojeda, V., M. Gelain, L. Sympson, and A. Trejo. 2003. Desarrollo molfologico y conductual de polios de aguilucho chico Buteo albigula (Aves: Accipitridae) en le noroeste de la Patagonia Argentina. Rev. Chil. Hist. Nat. 76:451-457. Olrog, C. 1979. Nueva lista de la avifauna Argentina. Fund. Miguel Lillo, Tucuman, Argentina. Pavez, E. 2000. Migratory movements of the White- throated Hawk {Buteo albigula) in Chile. / Raptor Res 34:143-147. Philippi, R. A. 1899. Anales de la Universidad de Chile 103’ 664. Trejo, A., V, Ojeda, and L. Sympson. 2001. First nest re- cords of the White-throated Hawk {Buteo albigula) m Argentina./. Raptor Res. 35:169-170. , V. Ojeda, L. Sympson, G., and M. Gelain, 2004. Breeding biology and nest characteristics of the White-throated Hawk {Buteo albigula) in northwestern Argentine Patagonia./. Raptor Res. 38:314—321. Zalles, J.I. and K.L. Bildstein (Eds.). 2000. Raptor watch: a global directory of raptor migration sites. BirdLife International, Cambridge, U.K. and Hawk Mountain Sanctuary, Kempton, PA U.S.A. Received 20 May 2003; accepted 9 February 2004 Letters J Raptor Res. 38(2):190-191 © 2004 The Raptor Research Foundation, Inc. Observation of the Chimango Caracara {Milvago chimango) Feeding on Common Lesser Toads {Bufo fernandezae) The Chimango Caracara {Milvago chimango) is a member of Falconidae that occurs throughout southern South America: Argentina, Chile, Uruguay, Paraguay, and southern Brazil (Olrog 1995, Las Aves Argentinas, Editorial El Ateneo, Buenos Aires, Argentina) . Various studies have described the Chimango Caracara as an opportunistic pred- ator and scavenger. Its diet has been reported to include arthropods, gastropods, worms, vertebrates, vegetables, and carrion (Barros Valenzuela 1960, Rev. Univ. 44-45:31-37, Nunez and Yahez 1981, Not. Mens. Mus. Nac. Hist. Nat. Chile 25.5-9, Nunez et al. 1982, Bol. Mus. Nac. Hist. Nat. Chile 39:125-130, Cabezas and Schlatter 1987, An. Mus. Hist. Nat Valparaiso 18:131-141). On 5 November 2001, from a distance of ca. 50 m, we observed a Chimango Caracara feeding upon a dead adult common lesser toad {Bufo fernandezae) . We made this observation in Los Portehos (34°53'45"S, 58°05'02'AV), a sub- urban region of La Plata city (Buenos Aires Province, Argentina) , where land uses include cattle ranching, floricul- ture, and horticulture. At the time of our observation, the caracara was perched on a fence post 1 m in height, which was located in a pasture. This fence post was situated 20-m south of a small, temporary pond where the common lesser toad breeds (pers. obs.) and ca. 30-m south from the caracara’s nest. The nest was in a eucalyptus tree {Eu- calyptus sp.) located along the edge of the pond. The caracara was pecking at the toad’s belly and swallowing pieces torn from the frog’s viscera and foreleg muscles. This observation constitutes the first report of the common lesser toad in the Chimango Caracara’s diet. Between September 2001 and February 2002, once a wk, we visited the site and examined the ground around fence posts in a fence line that passed within 200 m of the caracara’s nest. During our visits, we frequently saw the caracara perched on this fence line. We found 15 carcasses of the common lesser toad, remains of a Rufous Hornero {Furnarius rufus), a mouse (unknown species), and bones of a criolla frog {Leptodactylus ocellatus) around these perch- ing sites. Toad carcasses found at perching sites typically had been eviscerated through a ventral hole. The skeleton and dorsal skin remained intact and in some cases the carcasses were without legs. All toad carcasses found were deposited at the herpetological collection of the Institute de Limnologia Platense “Dr. Raul A. Ringuelet” under the number ILPLA A 491. Snout-vent length of the toad carcasses averaged 60.1 mm (±4 mm [SD], range = 55.6-68 mm, N = 16). The common lesser toad, along with other species of Bufo, has a very thick and glandular-dorsal skin and two prominent post-cephalic glands in a dorso-lateral position (parotoid glands). These glands secrete substances that are noxious or toxic to some predators (Duellman and Trueb 1986, Biology of Amphibians, The Johns Hopkins Univ. Press, Baltimore, MD U.S.A.). Despite this fact, several birds have been reported to feed on the common lesser toad including the Red-backed Hawk {Buteo polyosoma) , Burrowing Owl {Athene cunicularia) , American Kestrel {Falco sparv- enus\ Gallardo 1974, Anfibios de los Alrededores de Buenos Aires, Editorial Universitaria de Buenos Aires, Argentina) and Cattle Egret {Bubulcus ibis', Torres et al. 2000, Cuad. Herpetol. 14:81). Contrary to Gallardo’s (1974) field reports, Huertas and Vallejo (1988, Bol. Soc. Zool. Urug., 2° epoca, 4:46—49), based on laboratory observations, reported that the American Kestrel, which typically kills and eats a variety of non-bufonid anuran species, does not kill and eat the common lesser toad (including small-juvenile toads which have more toxins than adults), perhaps being unable to avoid irritation caused by the secretion of the toad’s dorsal glands. Corn (1993, Herpetol. Rev. 24:57) and Brothers (1994, Herpetol. Rev. 25:117) reported that the American Crow {Corvus brachyrhynchos) and Common Raven {Corvus corax) fed on the congeneric, and also toxic, boreal toad {Bufo boreas), eviscerating them from the ventral side, as described above. Species that feed successfully on the common lesser toad and other bufonids may be able to do so by making ventral holes in the frog’s bodies. This method of consumption may help the predator avoid the noxious substances. We captured and weighed several common lesser toads in order to assess their potential energetic value to the caracara. The toad’s small body size {x = 15.62 g ± 4.28 g SD, range = 10.26-24.88 g, N = 9) along with its toxicity suggests little energetic benefit relative to handling cost, for the caracara (body mass ca. 300 g) . However, during the breeding season, when rainfall is high, toads are numerous and are often observed concentrated around ponds (pers. 190 June 2004 Letters 191 obs.)- This seasonal abundance of the common lesser toad might compensate for what might otherwise be a marginal resource. We thank G. Finarelli for her assistance with fieldwork and J.L. Morrison and three anonymous reviewers for their comments on earlier versions of the manuscript. — Leandro Alcalde (e-mail address: alcalde@ilpla.edu.ar) and Sergio D. Rosset, Contribucion Cientifica n° 750 del Instituto de Umnologia Platense “Dr. Raul A. Ringuelet” (ILPLA), CC 712 (1900) La Plata, Argentina. Received 15 April 2002; accepted 21 December 2003 Associate Editor: Joan L. Morrison J. Raptor Res. 38(2) :191 © 2004 The Raptor Research Foundation, Inc. Consumption of a Ringed Kingfisher {Megaceryle torquata) by a White-tailed Hawk (BUTEO ALBICAUDATUS) IN SOUTHEASTERN BRAZIL The White-tailed Hawk {Buteo albicaudatus) is a poorly known species ranging from southern Texas to northern Argentinean Patagonia (Farquhar 1992, The Birds of North America, No. 30, Washington, DC U.S.A.). Few data are reported on its diet, which comprises insects, rodents, reptiles, and birds (Farquhar 1992, Sick 1993, Birds in Brazil: a natural history. Princeton Univ. Press, Princeton, NJ U.S.A.). Virtually no data are published on its ecology in South America. We observed a feeding event by the White-tailed Hawk in the 2300 ha Itirapina Ecological Station (22°12'S, 47°54'W), State of Sao Paulo, Brazil. On 23 April 1998, at 1300 H, while driving a car through the savannah grassland, we observed an adult White-tailed Hawk feeding on dead Ringed Kingfisher {Megaceryle torquata) . The fresh kingfisher remains were in a small tree, ca. 2 m above the ground. As we approached, the hawk flew away and the remains fell to the ground. Only the complete cranium, cervical vertebrae, ulna, metacarpals, phalanges, and some rectrices were left by the hawk when we inspected the carcass. The Ringed Kingfisher is a piscivorous and semiaquatic bird associated with rivers, ponds, lakes, and reservoirs, occurring from extreme southern Texas to southernmost South America (del Hoyo et al. 2001, Handbook of the birds of the world. Lynx Edicions, Barcelona, Spain). The nearest aquatic environment, a reservoir, was located ca. 2 km away from the observation site. It is possible, therefore, that the kingfisher could have been passing over the grassland savannah when captured. This may have been the case as the White-tailed Hawk is known to kill and consume prey in or nearby the site of predation (M.A.M. Granzinolli pers. obs.). The Brazilian subspecies, B. a. albicaudatus, has a mass ranging from 850-884 g (del Hoyo et al. 1994.) The Ringed Kingfisher body mass ranges from 305-341 g (Sick 1993). Therefore, the kingfisher represented 34.5-40.1% of adult mass of the hawk. Other authors have reported consumption of birds by White-tailed Hawks, but few with a mass of more than 300 g (see Farquhar 1992). However, 43 of 259 pellets from the State of Minas Gerais in southeast Brazil contained birds and, except for one individual with a mass of 72 g, all the others were less than 40 g (M.A.M. Granzinolli and J.C. Mottajunior unpubl. data). According to the latter study, which evaluated the hawk’s diet over a 1-yr period, birds are relatively uncommon prey, totaling 11.1% of consumed biomass of this species. Thus, the present observation suggests that this hawk subspecies can also prey upon larger birds occasionally. Also, we note that White-tailed Hawks are known to scavenge on dead animals (Farquhar 1992) and that the kingfisher carcass we found may not have been captured and killed by the hawk. Nonetheless, we suggest that the feeding event we observed was the result of predation and our record documents the consumption of a relatively large bird in the diet of the White-tailed Hawk. We thank Funda^:ao de Amparo a Pesquisa do Estado de Sao Paulo for financial support and Denise Zanchetta from Instituto Florestal de Sao Paulo for the license to conduct studies in the Ecological Station. C. Farquhar and Adriana A. Bueno made suggestions on the manuscript. This is publication No. 16 of the project “Ecology of the Cerrados of Itirapina.” — Jose Carlos Motta-Junior (e-mail address: mottajr@ib.usp.br) and Marco Antonio Monteiro GranzinoUi, Departamento de Ecologia, Instituto de Biociencias, Universidade de Sao Paulo, 05508-900, Sao Paulo, SP, Brazil. Received 11 June 2003; accepted 18 December 2003 192 Letters VoL. 38, No. 2 J Raptor Res. 38(2) :192 © 2004 The Raptor Research Foundation, Inc. Golden Eagle {Aquila chrysaetos) Predation Attempts on Merriam’s Turkeys {Meleagris GALLOPAVO MERRIAMI) IN THE SOUTHERN BLACK HILLS, SOUTH DAKOTA While trapping Merriam’s Wild Turkeys {Meleagris gallopavo merriami), we witnessed three predation attempts by Golden Eagles {Aquila chrysaetos) on turkeys during winter (January-March) and spring-summer (April^uly), 2001- 03. Merriam’s turkeys in the southern Black Hills of South Dakota primarily use (i.e., roost, feed, and loaf) xeric habitats dominated by ponderosa pine {Pinus ponderosa) . The first observation of an eagle attempting to prey upon turkeys occurred at a bait-site used to capture turkeys. At approximately 0800 H, 5 February 2001, 13 adult male turkeys were at the bait-site feeding while we observed from a ground blind. Four of the turkeys looked up and emitted alarm “putt” vocalizations (Williams 1984, The voice and vocabulary of the wild turkey. Real Turkeys, Gaines- ville, FL U.S.A.). Within 2-3 sec all the birds were alert and very vocal. At this point, we observed a Golden Eagle dive toward the turkeys. The turkeys flew into the trees, seeking shelter in a thick stand of young-ponderosa pine trees. The eagle followed the turkeys, but captured no birds. The turkeys did not return to the bait-site until the following day. A second attempt occurred while we were collecting habitat data in the afternoon (1400-1500 H) at a ponderosa pine feeding site on 23 January 2002. While walking toward a radio-marked female turkey in a flock containing 35 females and 10 males, we heard the flock emitting fast alarm “putt” vocalizations. Due to the steep terrain and thick cover, we were able to approach to within 40 m of the flock and could see several females above our position in a thick stand of young ponderosa pine. We noticed a Golden Eagle soaring overhead, and as the eagle neared the flock, the turkeys once again began to emit alarm “putt” vocalizations, which increased in intensity as the Golden Eagle approached the flock. When the eagle was within 80 m of the birds, it went into a dive and maneuvered through the young pine stand and into the flock of turkeys. After hitting several turkeys with its talons and body, the Golden Eagle and two turkeys rolled down the slope and stopped several m below the flock. Both the turkeys struck by the eagle regained their balance and ran back into the flock. Soon after, three different turkeys left the flock and ran at the eagle as it stood below. The turkey’s aggressive calling, quick movements, and flailing of wings at the eagle startled the eagle and it quickly left and glided off the slope avoiding further confrontation on the ground with the turkeys. Once in flight, the eagle soared twice over the flock at a height of about 10-15 m, never reentering the flock. The turkeys remained in the dense stand of young ponderosa pine as the eagle made two more approaches. A third predation attempt occurred while we were observing a radio-marked female and her 6-d-old brood along the edge of a meadow on 11 June 2003. We were roughly 70 m from the female and her brood, watching them feed along the edge of a meadow for 4 min when suddenly the female laid flat in the grass. A Golden Eagle immediately flew from the nearby trees, folded its wings, and dove into the grass ca. 5 m from the hiding female. The female then quickly rose from its hiding position and started emitting fast alarm “putt” vocalizations and circling the raptor trying to attract its attention. The Golden Eagle ignored the “putting” female and appeared to be consuming something on the ground beneath it. After 2 or 3 min the eagle became nervous and flew to a nearby perch. We immediately approached the kill site and found two dead poults. One poult had its head and neck eaten, the other poult was not consumed, but a necropsy revealed it had talon puncture wounds on the neck and breast. Other observations of wild turkey-raptor interactions have been reported. Rio Grande Wild Turkey {M. g. intermedia) behavior (i.e., alarm calls and heightened wariness) has been described for birds reacting to the harassment of overhead flying golden eagles (Thomas et al. 1964, Wilson Bull. 76:384-385). Poult protection behavior has been observed by Merriam’s females toward a goshawk {Accipiter gentilis) (Lehman 2003, Prairie Nat. 35:47—48) and by Rio Grande females toward a Red-tailed Hawk {Buteo jamaicensis) (Butts 1977, Southwest. Nat. 22:404-405). All of our observed predation attempts occurred within a 16-km radius of Pringle, South Dakota in the southern Black Hills. This study was supported by federal aid funds through the South Dakota Department of Game, Fish 8c Parks, and by the National Wild Turkey Federation. We thank L.D. Flake, M. Kochert, and two anonymous referees for reviewing this manuscript. — Chad P. Lehman (e-mail address: turkeys@gwtc.net) and Dan J. Thompson, Wildlife and Fisheries Sciences, South Dakota State University, Box 2140B, Brookings, SD 57007 U.S.A. Received 30 July 2003; accepted 13 February 2004 June 2004 Letters 193 / Raptor Res. 38(2):193-194 © 2004 The Raptor Research Foundation, Inc. A Record of the Ornate Hawk-Eagle {Spizaetus ornatus) in Nayarit, Mexico Ornate Hawk-Eagles {Spizaetus ornatus) inhabit tropical and subtropical zones, in well-preserved interior forests, from sea level to 1500 m. Habitat associations include tropical rainforests and deciduous forests, cloud forests, and occasionally pine-oak (Pinus-Quercus) forests (Inigo-EHas et al. 1987, Condor 89:671-672; Inigo-Elias 2000, pages 122- 124 in G. Ceballos and L. Marquez Valdelamar [Eds.], Las Aves de Mexico en Peligro de Extincion. CONABIO- UNAM-Eondo de Cultura Economica, Mexico). However, this species also has been recorded from old second-growth and coffee plantations with native trees providing canopy cover, Ornate Hawk-Eagles have been documented from southern Mexico to Colombia and Ecuador (Ihigo-EHas 2000). In Mexico, they have been recorded on the slope of the Gulf of Mexico, from Tamaulipas and San Luis Potosi to Chiapas and the Yucatan Peninsula (Fig. 1). On the Pacific slope they have been recorded in the state of Colima and Jalisco, with an isolated record from Guerrero (Ihigo-Elias 2000). Ornate Hawk-Eagles have always been considered uncommon to rare, with low reproductive po- tential, producing one offspring every 2 yr (Ihigo-EHas 2000) . Habitat requirements, low productivity, and low abun- dance make them highly vulnerable to extinction (Ferguson-Lees and Christie 2001, Raptors of the world. Houghton Mifflin Company, New York, NYU.S.A.). During a mammal survey of the southwestern portion of the state of Nayarit, Mexico, we observed and photo- graphed an Ornate Hawk-Eagle on 22 February 2003, at 1300 H soaring at a low altitude not more than 100 m above the canopy, constantly calling. The locality was 105°13'W and 21°41'N, elevation 212 m; southwest of the community named “El Cora,” within the municipality of San Bias, Nayarit. The eagle perched first on a torote tree {Burserasp ) and moved to an unidentified snag 10 min after it was first observed perched; the height of both trees was >20 m The habitat is a semi-evergreen rainforest, with an abundant source of water from a nearby river. The site is within a single 225-km^ patch of semi-evergreen forest (Palacio-Prieto et al. 2000, Invest. Geogr. Bolet. Instit. Geogr. UNAM 43- 183-203), apparently protected from development. We estimated the age of the observed individual to be transitional, -116 -112 -108 -104 -100 -96 -92 -88 32 28 24 20 16 Figure 1. Distribution range for Ornate Hawk-Eagle, modified from Inigo-EHas (2000) and Howell and Webb (1995). The star shows the Nayarit record, black circles are verified records. 194 Letters VoL. 38, No. 2 between 2- and 3-yr-old, but not yet a mature adult (Gonzalez Garcia and Inigo-Elias pers. comm.). Distinct characters for identification were the plumage, the barred legs, and flight pattern (Inigo-Elfas 2000) . The nearest verified records for the Ornate Hawk-Eagle are located in Sierra Autlan, Jalisco (Schaldach 1969, An. Inst. Biol. T7VAM 40:299-316) and the town of Pueblo Juarez, Colima (Schaldach 1963, Proc. West. Found. Vertebr. Zool. 1:1-100), located 200 and 280 km, respectively, from our sighting. Several authors (Inigo-Elfas 2000, Howell and Webb 1995, A guide to the birds of Mexico and northern Central America, Oxford Univ. Press, London, U.K.) delineate the Pacific slope range of Ornate Hawk-Eagle into Jalisco, based on one verified record in the southern portion of Jalisco. At least one hawk-eagle, the Javan Hawk-Eagle {Spizaetus bartelsi), apparently shows long-distance dispersal capability between patches of suitable habitat (>37 km; S. van Balen, V. Nijman, and H.H.T. Prins 2000, Biol. Cons. 96:297- 304) . Even if these movements are typical of the genus Spizaetus, our record is disjunct from other reported sightings, which probably indicates that the observed hawk-eagle came from the nearest population in Jalisco. Ornate Hawk- Eagle territories may include 13.75 km^ in the tropical rainforest of Guyana (Thiollay 1989, Cons. Biol. 3:128-137). If our record was a hawk-eagle from the Jalisco population it would have traveled ca. 54 home-range diameters. This observation increases the known range of the Ornate Hawk-Eagle and emphasizes the lack of biological data for most of the mountain ranges in the western Pacific slope of Mexico. We strongly recommend initiating surveys for Ornate Hawk-Eagles and other raptors in the mountains between our sighting record and the known Jalisco population. We would like to thank Fernando Gonzalez and Eduardo Ihigo-Elias for corroborating the species identity based on our photograph. We would also like to thank Allen Fish (Golden Gate Raptor Observatory) and Erin Boydston (USGS Golden Gate National Recreational Area) for their comments and help on the literature review. We would also like to thank the reviewers. — Carlos A. Lopez GonzMez (e-mail address: cats4mex@aol.com), Eduardo Ponce Guevara, Karla Pelz Serrano, Hugo Lima Soria, and Rodrigo Sierra Corona, Licenciatura en Biologia, Universidad Autonoma de Queretaro, Cerro de las Campanas S/N, Col. Ninos Heroes, C. P. 76010, Queretaro, Queretaro, Mexico. Received 21 June 2003; accepted 27 January 2004 A Telemetry Receiver Designed with The Researcher in Mind What you've been waiting for! Finjlly. a htcjhly st'initivc 9^»9 ctiannc< synthrsi/ed tolcmetry leceiver that weighs lesi than 13 ounces, is completely u\er programmable and oHers variable ican rates over all frequencies. 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Grants and Awards For details and additional information visit: http:/ /biology.boisestate.edu/raptor/rrfi.htm Awards for Recognition of Significant Contributions. The Tom Cade Award is a non-monetary award that recognizes an individual who has made significant advances in the area of captive propagation and reintroduction of raptors. The Fran and Frederick Hamerstrom Award is a non-monetary award that recognizes an individual who has contributed significantly to the under- standing of raptor ecology and natural history. Submit nominations for either award to: Dr, Clint Boal, Texas Cooperative Fish and Wildlife Research Unit, BRD/USGS, Texas Tech University, 15th Street & Boston, Ag Science Bldg., Room 218, Lubbock TX 79409-2120 U.S.A.; phone: 806-742-2851; e-mail: cboal@ttu.edu Awards for Student Recognition and Travel Assistance. The James R. Koplin Travel Award is given to a student who is the senior author and presenter of a paper or poster to be presented at the RRF meeting for which travel funds are requested. Application deadline: due date for meeting abstract. Contact: Dr. Patricia A. Hall, 5937 E. Abbey Rd., Flagstaff, AZ 86004; phone: 520-526-6222 U.S.A.; e-mail: pah@spruce.for.nau.edu The William C. Anderson Memorial Award is given to both the best student oral and poster presentation at the annual RRF meeting. The paper cannot be part of an organized symposium to be considered. Application deadline: due date for meeting abstract, no special application is needed. Contact: Rick Gerhardt, Sage Science, 319 SE Woodside Ct., Madras, OR 97741 U.S.A; phone: 541-475-4330; email: rgerhardt@madras.net Grants. Application deadline for all grants is February 15 of each year; selections will be made by April 15. The Dean Amadon Grant for up to $1000 is designed to assist persons working in the area of systematics (tax- onomy) and distribution of raptors. The Stephen R Tully Memorial Grant for up to $500 is given to support research and conservation of raptors, especially to students and amateurs with limited access to alternative funding. Agency proposals are not accepted. Contact for both grants: Dr. Carole Griffiths, 251 Martling Ave., Tarrytown, NY 10591 U.S.A.; phone: 914-631-2911; e-mail: cgriff@liu.edu The Leslie Brown Memorial Grant for up to $1400 is given to support research and/or the dissemination of information on African raptors. Contact: Dr. Jeffrey L. Lincer, 9251 Golondrina Drive, La Mesa, CA 91941, U.S.A.; e-mail: JeflLincer@tns.net