(issn oesa-mG) The Joe RNAL OF Raptor Research Volume 22 Autumn 1988 Number 3 Contents The Relationship of Vegetative Cover to Daily Rhythms of Prey Consumption by American Kestrels Wintering in Southcentral FLORIDA. John A. Smallwood 77 Road Mortality of the Little Owl (. Athene noctua) in Spain. Mauro Hernandez 81 Short Communications Nesting of Falco tinnunculus in Natural Sites in Canary Pines on El Hierro Island. Jose Carrillo, Manuel Nogales and Manuel Padron 85 Red Fox Predation on Fledgling Egyptian Vultures. Jose Antonio Donazar and Olga Ceballos 88 Red-tailed Hawk “Captured” by a Striped Whip Snake. Clyde L. Pritchett and James M. Alfonzo 89 First Record of the Mississippi Kite for Bolivia. Denice Shaw and Terry C. Maxwell .... 90 Nocturnal Flight by Turkey Vultures ( Cathartes aura ) in Southcentral Texas. Stephen P. Tabor and Chris T. McAllister 91 Incidence of Black-phase Plumage in Ferruginous Hawks Nesting in Central North Dakota. Paul M. Konrad and David S. Gilmer 92 Great Horned Owl Observed “Hawking” Insects. James R. Duncan and Patricia A. Lane 93 Dissertation Abstracts Winter Territoriality and Predation Ecology of American Kestrels ( Falco sparverius ) in Southcentral Florida. John A. Smallwood 94 Thesis Abstracts Behavioral Development of Young Golden Eagles at a Hack Site: A Comparison to Wild Eaglets. Dan Allan Roberts 95 News and Reviews 84, 95, 96 Persons interested in predatory birds are invited to join The Raptor Research Foundation, Inc. Send requests for information concerning membership, subscriptions, special publications, or change of address to Jim Fitzpatrick, Treasurer, 12805 St. Croix Trail, Hastings, Minnesota 55033, U.S.A. The Journal of Raptor Research (ISSN 0892-1016) is published quarterly for $15.00 per year by The Raptor Research Foundation, Inc., 12805 St. Croix Trail, Hastings, Minnesota 55033, U.S.A. Application to mail at second class rate is pending at Hastings, Minnesota, and additional mailing office. Printed by Allen Press, Inc., Lawrence, Kansas, U.S.A. Copyright 1988 by The Raptor Research Foundation, Inc. Printed in U.S.A. THIS PUBLICATION IS PRINTED ON ACID-FREE PAPER. THE JOURNAL OF RAPTOR RESEARCH A QUARTERLY PUBLICATION OF THE RAPTOR RESEARCH FOUNDATION, INC. Vol. 22 Autumn 1988 No. 3 J Raptor Res. 22(3):77-80 © 1988 The Raptor Research Foundation, Inc. THE RELATIONSHIP OF VEGETATIVE COVER TO DAILY RHYTHMS OF PREY CONSUMPTION BY AMERICAN KESTRELS WINTERING IN SOUTHCENTRAL FLORIDA John A. Smallwood Abstract. — American Kestrels ( Falco sparverius) wintering in southcentral Florida were captured in order to collect their pellets. Dry mass of pellets was used as an index to the accumulated mass of prey consumed between dawn, when pellets representing prey consumed the previous day were regurgitated, and time of capture. Kestrels holding territories covered by a large proportion of suitable hunting substrate (grasses and weedy forbs <25 cm in height) consumed greater prey mass during morning than did kestrels inhabiting territories of lesser foraging quality. No difference was found between territories of high and low foraging quality in terms of total prey mass consumed by the end of the day. For reasons unrelated to habitat preference, most territories of high foraging quality were occupied by females, but within habitats of either high or low foraging quality, the temporal patterns of prey mass accumulation by males and females were similar. These results are consistent with observed kestrel activity budgets, and lend further support to the hypothesis that observed temporal differences in foraging behavior between males and females were due to differences in foraging quality of their territories; there was no evidence of any inherent sex-specific differences in predatory behavior. Foraging quality of kestrel winter territories in the study area was a function of the extent to which locations were covered by open patches of mutually preferred foraging substrate. Segregation by habitat in wintering American Kestrels {Falco sparverius) has been widely reported (Koplin 1973; Mills 1976; Stinson etal. 1981; Small- wood 1981, 1987; Bohall-Wood and Collopy 1986). Several lines of empirical evidence have been pre- sented which strongly suggest that the solitary winter territories held by female kestrels in southcentral Florida differ substantially from those held by males in regard to foraging quality; 1) females were more common than males in habitats extensively covered by suitable hunting substrate, 2) the territories of females were characterized by fewer and smaller trees and shrubs (woody vegetation was negatively correlated with coverage by suitable hunting sub- strate and obstructed the views of foraging kestrels), 3) males were less likely than females to reject an opportunity to capture novel prey items, and 4) males suffered a greater absolute and relative weight loss in response to weather-related decreases in prey availability (Smallwood 1987). Differential habitat use by the sexes was shown to be related to the date of arrival on wintering grounds, most of the adult males arriving last, rather than to differences in habitat preference (Smallwood 1988). In fact males and females established terri- tories in the same type of habitat, when available, and all kestrels utilized open patches of the same type of foraging substrate regardless of the overall vegetative structure of the territory. Diets of males and females were also similar; both sexes fed exclu- sively on arthropods during winter (Smallwood 1987). In a study of kestrel activity budgets (Smallwood 1987), it was shown that males and females had virtually identical capture success, once a capture was initiated, and captured similar numbers of prey 77 78 John A. Smallwood Vol. 22, No. 3 each day. However, sexes exhibited markedly dif- ferent daily rhythms of foraging activity. The rate at which males made capture attempts did not change significantly throughout the day. In females, how- ever, rates increased during morning, reaching a peak before noon. Hunting activity of females was markedly lower during early afternoon, increased in mid-afternoon and then waned toward evening. Differences in daily foraging rhythms were in- terpreted as evidence of differential foraging quality of the respective territories. Apparently, most males were constrained to forage actively throughout the day in order to capture a sufficient number of prey items. Because females were more likely to be oc- cupying territories of relatively high foraging qual- ity, they were able to meet a large portion of their prey requirements early in the day. Later in the day, females allotted more time toward nonforaging ac- tivities. The above interpretation was based on the as- sumption that mean prey size did not differ for males and females, that is, the similar number of prey items consumed/d by males and females represented sim- ilar nutrient rewards. Given the observed differences in daily foraging rhythms between the sexes and the assumption of equal mean prey size, the cumulative prey mass (CPM) consumed by females should differ from the CPM of males in a predictable manner throughout the day. The CPM of females should be greater than that of males during morning, when female foraging rates reach a maximum. The much reduced foraging activity of females in the early afternoon, during which males still actively forage, and the similarity of the total daily number of prey captures should result in similar CPM values for males and females during afternoon. If differences in CPM values are due to differential foraging qual- ity rather than to an inherent sex-specific difference in foraging behavior, then kestrels holding territories of similar foraging quality should exhibit similar temporal patterns of prey mass accumulation, re- gardless of gender. The objective of this study was to examine the temporal patterns of prey mass accumulation by male and female kestrels occupying winter territories cov- ered to various extents by grasses and weedy forbs <25 cm in height. In this manner, the importance of kestrel gender and territory habitat were com- pared in regard to foraging behavior. In addition percent coverage by suitable hunting substrate, as defined above, was evaluated as a reliable indicator of the foraging quality of kestrel winter territories. Study Area and Methods The study area was centered on 27°00'N, 81 a 20'W, west of Lake Okeechobee in southcentral Florida and included portions of Highlands, Glades and Hendry counties. Most of this land is covered by pastures, citrus groves and res- idential developments. Numerous ponds, slash pine ( Pinus elliotii ) plantations, scrubby flatwoods and cypress ( Tax- odium distichum ) sloughs are situated throughout the area (see Smallwood 1987). Kestrels do not begin their daily foraging activities until after regurgitation of the undigested material from prey consumed on the previous day (Balgooyen 1971; pers obs.). Thus, kestrels begin foraging “on an empty stom- ach,” and the indigestible food material which then ac- cumulates is a record of that day’s prey consumption. Pellet mass was considered an index of the mass of consumed prey. Kestrels were captured with a modified bal-chatn trap (Berger and Mueller 1959) from 3 January-23 February 1984, and from 18 December 1984-2 February 1985 Time of day of capture was recorded, and captured birds were held in cages overnight and regurgitated pellets col- lected the following morning. Each kestrel was subse- quently released near its capture site. Pellets were air- dried at least 96 h prior to being weighed to the nearest 0.0001 g (Mettler AE 163 digital balance, Mettler In- strument Corp., Highstown, NJ). Because 97.5% of all observed capture attempts by kes- trels directed toward naturally occurring prey were made onto substrates of grasses or weedy forbs <25 cm in height (Smallwood 1987), this category of ground vegetation was operationally defined as suitable hunting substrate. The foraging quality of kestrel territories was estimated by sampling a 1-ha circular plot centered on each kestrel’s hunting perch at the time of capture, measuring percent coverage by suitable hunting substrate (see Smallwood 1987 for a detailed description of the sampling technique) Data were analyzed in the following manner. Kestrel territories were ranked with respect to the estimate of percent coverage by suitable hunting substrate. The ranked list of territories was then divided arbitrarily into two groups of approximately equal sample size, the respective pellets representing territories with >50% coverage by suitable hunting substrate (high foraging quality) or ter- ritories with coverage <50% (low foraging quality). Each pellet thus represented either a male or female kestrel captured either before or after solar noon (i.e., either a morning or afternoon CPM value) from a territory of either high or low foraging quality. Association between kestrel gender and foraging quality of the territory was tested for significance with a Chi-square test of homoge- neity (Fienberg 1977). With respect to mass, pellets rep- resenting high and low foraging quality habitats were compared with Wilcoxon’s rank sum tests (Hollander and Wolfe 1973) separately for four combinations of kestrel gender and time of day. In addition, males were compared to females with respect to pellet mass with Wilcoxon’s Autumn 1988 Kestrel Prey Consumption Rhythms 79 rank sum tests separately for four combinations of foraging quality and time of day. Results Pellets were collected from a total of 1 69 kestrels. Pellets from 33 individual kestrels were chosen at random and were sacrificed for a concurrent study. Thus, results were obtained from measurements of 136 pellet samples. Foraging quality of territories was significantly associated with kestrel gender. Of the 82 females sampled, 67% occupied territories of high foraging quality; only 20% of the 54 males sampled were found in high quality habitats (x 2 = 28.43, P < 0 . 001 ). For birds captured before solar noon, pellets rep- resenting locations of high foraging quality had sig- nificantly greater mass than those representing ter- ritories of lower foraging quality for both males and females (Wilcoxon’s Z = 1.81, P = 0.036, and Z = 1.69, P = 0.045, respectively; Fig. la). No associ- ation between pellet mass and the foraging quality of the respective territories was found for pellets representing afternoon CPM values for either males or females (Z = 0.68, P = 0.50, and Z = 0.88, P = 0.38, respectively; Fig. lb). No differences in pellet mass were found between males and females in high quality habitats during morning (Z = 0.27, P = 0.80) or afternoon (Z = 0.93, P = 0.35), or in low quality habitats during morning (Z = 0.04, P = 0.97) or afternoon (Z = 0.91, P = 0.37). Discussion Several interrelated conclusions may be drawn from these results. First, these data support the mod- el of prey mass accumulation rhythms for kestrels inhabiting territories of various foraging quality, as suggested by the observed difference in kestrel ac- tivity budgets (Smallwood 1987). Kestrels occupying the “best” habitats differed from those in poorer habitats in rate of prey mass accumulation early in the day, but not in total prey mass consumed by the end of the day. It is unlikely that a kestrel would normally occupy a territory of such poor foraging quality that a sufficient mass of prey could not usu- ally be captured on a daily basis. It has been demonstrated previously that males and females consume a similar number of prey items per day (Smallwood 1987), and the present study suggests that the total daily mass of prey consumed by males and females is also similar. If the relation- cn to i- LU UJ CL >- tr o Ll o to to < 1.5 1.2 0.9 0.6 0.3 0 2.7 2.4 2.1 a. r l GOOD b. 1 . 8 - M males I | FEMALES 7 29 20 0 l 1 I 1 GOOD POOR FORAGING QUALITY OF TERRITORY Figure 1. Cumulative mass of prey consumed a) before solar noon and b) throughout the day by American Kestrels occupying winter territo- ries in southcentral Florida. Mass of dry pel- lets was used as an index of consumed prey mass. Ranges, quartile deviations and sample sizes are shown. Territories with >50% cov- erage by suitable hunting substrate (grasses or weedy forbs <25 cm in height) were consid- ered to be of good foraging quality; territories with suitable hunting substrate coverage < 50% were considered poor. 80 John A. Smallwood Vol. 22, No. 3 ship between prey mass and pellet mass is the same for each sex, then mean size of prey captured by males and females must also be similar. In addition it appears that mean size of prey captured by kestrels is not dependent on foraging quality of a territory. Relative to large patches, small patches of suitable hunting substrate apparently support prey com- munities which are similar in terms of prey size. If prey density is a function of the type and height of ground vegetation, rather than of patch size, then total prey mass available to kestrels is proportional to patch size. The amount of coverage by suitable hunting sub- strate was successfully used to predict differences in CPM values. This result corroborates that percent coverage by grasses or weedy forbs <25 cm in height is a biologically meaningful measure of the quality of a location in southcentral Florida with respect to foraging by kestrels. Preference for open patches of short ground vegetation by hunting kestrels has been well documented (e.g., Balgooyen 1976). Results of this study lend further support to the hypothesis that observed temporal differences in for- aging behavior between males and females (Small- wood 1987) were due to differences in the foraging quality of their territories rather than to inherent sex-specific differences in predatory behavior. Al- though males and females, on average, occupy dif- ferent macrohabitats (Smallwood 1987, 1988), they depend on the same microhabitats for foraging. Both sexes feed on the same kinds of prey (see also Cade 1960; Balgooyen 1976) captured in open patches covered by the same kind of hunting substrate. It appears that the foraging quality of kestrel winter territories in southcentral Florida is a function of the extent to which locations are covered by open patches of grasses and weedy forbs <25 cm in height. Those kestrels which occupy territories of similar foraging quality forage similarly, regardless of gen- der. Acknowledgments I am grateful to T. C. Grubb, Jr., T. A. Bookhout, and T. J. Coonan for critical reviews. Field assistance was provided by M. A. Smallwood, M. S. Woodrey, N. J. Smallwood, and S. L. Morgan. This study was supported by funds from The Ohio State University, Archbold Bi- ological Station, Hawk Mountain Sanctuary Association, and Sigma Xi. This study represents a portion of the dissertation research conducted in partial fulfillment of the requirements for a doctoral degree in Zoology at The Ohio State University. Literature Cited Balgooyen, T. G. 1971. Pellet regurgitation by captive Sparrow Hawks ( Falco sparvenus). Condor 73:382-385. . 1976. Behavior and ecology of the American Kestrel ( Falco sparverius L.) in the Sierra Nevada of California. Univ. Calif. Publ. Zool. 103:1-83. Berger, D. D. and H. C. Mueller. 1959. The bal- chatri: a trap for the birds of prey. Bird-Banding 30: 18-26. Bohall-Wood, P. and M. W. Collopy. 1986. Abun- dance and habitat selection of two American Kestrel subspecies in north-central Florida. Auk 103:557-563. Cade, T. J. 1960. Ecology of the Peregrine and Gyr- falcon populations in Alaska. Univ. Calif. Publ. Zool 63:151-290. Fienberg, S. E. 1977. The analysis of cross-classified data. MIT Press, Cambridge. Hollander, M. and D. A. Wolfe. 1973. Nonpara- metric statistical methods. John Wiley & Sons, New York. Koplin, J. R. 1973. Differential habitat use by sexes of American Kestrels wintering in northern California Raptor Res. 7:39-42. Mills, G. S. 1976. American Kestrel sex ratios and habitat separation. Auk 93:740-748. SMALLWOOD, J. A. 1981. Prey size selection by wild American Kestrels ( Falco sparverius) wintering in southcentral Florida. M.Sc. thesis, Miami Univ., Ox- ford, Ohio. . 1987. Sexual segregation by habitat in Amer- ican Kestrels ( Falco sparverius) wintering in southcen- tral Florida: vegetative structure and responses to dif- ferential prey availability. Condor 89:842-849. . 1988. A mechanism of sexual segregation by habitat in American Kestrels {Falco sparverius) win- tering in south-central Florida. Auk 105:36-46. Stinson, C. H., D. L. Crawford and J. Lauthner 1981. Sex differences in winter habitat of American Kestrels in Georgia. J. Field Ornith. 52:29-35. Department of Zoology, 1735 Neil Ave., The Ohio State University, Columbus, OH 43210. Present ad- dress: Department of Wildlife and Range Sciences, University of Florida, Gainesville, FL 32611. Received 8 September 1987; accepted 1 June 1988 /. Raptor Res. 22(3):81-84 © 1988 The Raptor Research Foundation, Inc. ROAD MORTALITY OF THE LITTLE OWL {Athene noctua ) IN SPAIN Mauro Hernandez Abstract. — We studied the causes of road mortality of the Little Owl {Athene noctua ) in Spain based on 418 road casualties and their relation to road characteristics and type of roadside cover. Road mortality presents a clear seasonal pattern and a summer peak (August) was found to be associated with postfledging dispersion. Road illumination decreases road mortality. Roadside cover has an important influence upon road casualties, possibly as a consequence of perching. Higher numbers of deaths occur in shrub type vegetation of <1 m height. These results and those obtained by other authors are discussed. The Little Owl {Athene noctua ) is the most gen- eralist strigiforme in the Iberian Peninsula, and the most widely distributed and most common owl in Spain. In spite of this, many aspects of the biology of this species are unknown. The Little Owl was poorly documented (Valverde 1967; Agelet 1979; Hoz 1982) until the studies of Manez (1983a and 1983b). No information is avail- able on the species’ status in Spain, and mortality has never been studied in Spain (Clark et al. 1978). Mortality of strigiformes in Spain was poorly treated by Garzon (1977) and, particularly on Bubo bubo (see Gonzalez et al. 1980). Westernhagen (1962) reported on numerous road casualties of kites {Mil- vus sp.) in Andalusia (southern Spain) and Hass (1978) included Spanish roads in his study. In Europe, particularly in Great Britain, Ger- many, the Netherlands and Denmark, road mortal- ity among birds is well documented. Hodson (1962) studied the various types of roadside cover and its influence upon bird casualty numbers. Dunthorn and Errington (1964) made an attempt to measure the effects of such deaths on the bird population. Hansen (1969) divided roads into categories using traffic density as a norm and, lastly, Brautigam (1978) discussed the seasonal distribution of road deaths. Nevertheless, the Little Owl appears only occa- sionally in those samples, and for this reason the results of these observers are dubious for application to the species and to Spain. The purpose of this study was to establish the causes of road mortality of the Little Owl in Spain and to advance knowledge on non-natural mortality of this species. Materials and Methods Data were compiled in a 3-yr period (1984-1986) in Central Spain. A total of 418 collisions with cars in Spain were studied. Position, date of death and, when known, age of each owl casualty were recorded. Features of the road and the type of roadside cover were also recorded, including the presence or absence of illumination, the pres- ence or absence of road margin vegetation and its features, and the type road. Road margin vegetation was studied only in non-illu- minated roads in an area of 20 m width from the road border and 10 m length on each side from the location of the carcass. Vegetation >3 m in height was considered as woodland. If no homogeneous vegetation was found, the presence of only 1 tree was deemed sufficient for classi- fication as woodland. The other class of vegetation was shrub vegetation which was <3 m height. In many cases no information was available on the distance from where a bird was found to the next curve in the road, and so, the types of roads have been classified by calculating the number of curves in 10 km of road. On this basis, three road classes resulted as follows: 1) roads with no more than 10 curves/10 km; 2) roads having between 10 and 25 curves/10 km; and 3) roads with >25 curves/ 10 km. Results Of 418 total collisions recorded during the study, 40 were excluded due to insufficient data being avail- able. Mortality caused by car collisions represents 82% of non-natural deaths in Athene noctua:, al- though in some cases this value may be considerably higher. The remaining 18% were attributed as fol- lows: shot (4.3%); caught in nest (3.1%); trapped (0.9%); preyed upon (3.5%); unknown (1.9%) and other causes (4.3%), including falling from nest, being waterlogged, cannibalism and starvation. Results concerning the seasonal variation in mor- tality are given in Figure 1. The time of greatest mortality was recorded in summer. Between 1 Au- gust and 1 5 August we found 63.2% of the 378 deaths studied; 17.1% between 15 July and 31 July, and 81 82 Mauro Hernandez Vol. 22, No. 3 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC MONTH Figure 1. Histograms showing the pattern of seasonal mortality by half-month periods. 7.1% between 1 July and 15 July. During the re- mainder of the year (21 2-wk periods) were found the remaining 12.6% (47 deaths). With respect to age of Little Owls found, among 353 (93.3%) found between 1 July and 1 November, only 25 (7.0%) were adults, the remainder being juvenile birds identified by their characteristic plum- age. All car collisions occurred during the night. On illuminated roads only 9 Little Owl deaths (2.3%, N = 378) were recorded, all of them being young owls; 369 (97.6%) were found on non-illuminated roads. Power transmission or telephone lines parallel to roads were not associated with car collisions and are generally placed <20 m from the road. Of the 369 deaths found on non-illuminated roads, in 75 cases (20.3%) there was woodland vegetation in the road margin area and in the remainder (294 cases, 79.6%) the vegetation was of the shrub type. We found 1 84 deaths (62.5%) occurred on roads with vegetation of no more than 0.5 m height and 110 deaths (37.4%) occurred on roads with a vegetation of 0.5-1 m height in road margins. On roads with a vegetation height of 1-3 m no deaths were found. Often in the margin of several roads the two types of vegetation defined were alternatively distributed in which case carcasses were found only in areas of shrub vegetation. Discussion According to the available data, road casualties are the most important cause of non-natural mor- tality of the Little Owl in Spain. Nevertheless, it is possible that road deaths may have been over rep- resented since birds killed on the road are more likely to be found than those killed in most other ways (Hodson and Snow 1965). In Europe deaths on roads are not as frequent but represent an important frac- tion of owls killed by human influence (Glue 1971; Weir 1971; Glue and Scott 1980; Exo and Hennes 1980). Collisions with cars can be produced when bright lights at night cause temporary blindness of owls (Labisky 1960, in litt.) and as a result of owls swoop- ing towards a moving light (Hodson 1962). Sutton (1927) suggested this as a cause of Screech Owls ( Otus asio ) being killed by cars. For these reasons and perhaps others, all road casualties occurred at night (M. Manez, pers. comm.) and are also the main differences in road deaths between diurnal and nocturnal birds. Along illuminated roads, mortality Autumn 1988 Little Owl Mortality in Spain 83 is less (only 2.3%), and possibly Little Owls are not blinded in illuminated areas or are so with less crit- ical intensity. Hansen (1969) suggested that bird behaviour de- termines whether a species is liable to be killed in traffic or not, and perhaps this can explain why the Little Owl is more frequently killed by cars than other owls. Road mortality presents a clear seasonal pattern. In the first half of August we found a very conspicuous increase in mortality (Fig. 1) producing 63.2% of the annual deaths in only 15 d approxi- mately. Summer mortality has also been reported by Glue (1973, in lift.) and Exo and Hennes (1980). In our study, however, the summer peak occurred late in August and was not associated with stress of the breeding season as suggested by Exo and Hennes (1980) due to a greater proportion of young in our sample (92.9% between 1 July and 1 November), but to postfledging dispersion occurring during this time (Glue and Scott 1980). Glue and Scott (1980) found that between 1 July and 1 September 40% of young died, most of them on roads. Dunthorn and Errington (1964), Haas (1964), Hodson and Snow (1965) and Hansen (1969) have also reported an increase in road casualties during this time frame and note the influence of a greater proportion of inexperienced young on the observed increase. The trend of the Little Owl to frequent open areas influences the relationship between number of deaths and roadside cover. Nevertheless, we think that, in this study, the influence is very small due to the small amount of open regions of the study area. The influence of road margin vegetation on casualties is a consequence of perch availability because owls are rarely killed while crossing roads. Vegetation of <1 m is classified as shrub and is not adequate for perch- ing and causes Little Owls to use the pavement as a perch. Hodson (1962) established that much higher number of deaths occur opposite gaps and openings than along stretches of roadway with uniform bor- der, because most birds are killed while attempting to fly from one side of the road to the other through these gaps (Dunthorn and Errington 1964). The presence of trees in the proximity of a road (<20 m) was associated with decreased road mor- tality (20.3%). However, the most adequate vege- tation, according to the information obtained is that between 1 and 3 m height and located at <20 m from the road and not woodland as found by Hodson (1962) for other birds. In many cases the perch was not a tree or a shrub but a wall or a barrier. Table 1. Number and percentage of deaths of the Little Owl in Spain associated with various roadway conditions. Road Condition N % Road Characteristic Illuminated 9 2.3 Non-illuminated 369 97.6 Total 378 99.9 Roadside Cover Woodland 75 20.3 Shrub 294 79.6 Total 369 99.9 Shrub Height 0.0-0. 5 m 184 62.5 0. 5-1.0 m 110 37.4 1. 0-3.0 m 0 0 Total 294 99.9 Road Classification Class 1 32 8.4 Class 2 281 74.4 Class 3 65 17.1 Total 378 99.9 Speed and density of traffic have an important influence upon bird road casualties (Dunthorn and Errington 1964) and the greatest mortality is reg- istered on roads where traffic is dense and fast mov- ing (Hansen 1969). The number of casualties on Class 2 roads (Table 1) is higher than on those of Class 3 and Class 1. Nevertheless, the speed of traffic is the highest on Class 1 roads and is the lowest on Class 3. This may be explained by the fact that on Class 2 roads there are enough curves to prevent the owls from seeing cars far away, and also preventing cars from reaching high speed, while on Class 3 roads the speed should be low and on Class 1 roads cars are seen by the owls with time enough to leave the road. Finally, as a practical measure to avoid car col- lisions of Little Owls, it is advisable to place trees or shrubs near roads, or if it is possible, 2 m height perches should be placed 5 m from the road border and 10 to 15 m apart. Acknowledgments I thank Eduardo Castrillo, Miguel A. Carro and Al- berto Fernandez- Arias for critically reading an earlier version of the manuscript, Manuel Manez for his com- ments and suggestions and Juan M. Hernandez for the 84 Mauro Hernandez Vol. 22, No. 3 English translation. I acknowledge the support for this study, provided by the Asociacion para la Defensa de las Estrigiformes Ibericas — ADES. I also appreciate the as- sistance of ADENA 2000 (Barcelona); ANAT-LANE (Navarra); ANES (Toledo); M. A. Carro; S. Gerradelo; J. C. del Olmo; C. Fernandez; A. Fernandez- Arias; J. L. Garcia; J. Izquierdo; V. Machuca; O. Maroto; J. I. Mar- tin; A. Melero; C. Palacin; D. Saavedra and I. Sanchez. Literature Cited Agelet, A. 1979. Notas sobre la alimentacion de Mo- chuelo comun — Athene noctua (Aves, Strigidae). Misc. Zool. 5:186-188. Brautigam, H. 1978. Vogelverluste auf einer fernver- kehrstrabe von 1974 bis 1977 in den kreisen Atenburg und Geithain. Orn. Mitt. 30:147-149. Clark, R. J., D. G. Smith and L. H. Kelso. 1978. Working bibliography of owls of the world. Nat 7. Wildl. Fed. Sci. & Tech. Series , No. 1. Washington, DC. Cramp, S. A. (Ed). 1985. The birds of the Western Palaearctic. Vol. IV, pp. 514-525. Oxford Univ. Press, Oxford. Dunthorn, A. A. and F. P. Errington. 1964. Cas- ualties among birds along a selected road in Wiltshire. Bird Study 1 1 (3): 1 68—1 82. Exo, K. M. and R. Hennes. 1980. Beitrag zur Po- pulationsokologie des Steinkauzes ( Athene noctua ). Die Vogelwarte 30:162-179. Garzon, J. 1977. Birds of prey in Spain: the present situation. Pages 159-170. In R. D. Chancelor, Ed. World Conference on birds of prey. Report Proceed- ings, ICBP. Glue, D. E. 1971. Ringing recovery circumstances of some small birds of prey. Bird Study 18(3): 137-1 46. and D. Scott. 1980. Breeding biology of the Little Owl. Brit. Birds 73:167-180. Gonzalez, J. L., J. Lobon, L. M. Gonzalez y F. Pa- lacios. 1980. Datos sobre la evolucion no natural de la mortalidad de Bubo bubo en Espaha durante el pe- riodo 1972-1980. Bol. Est. C. Ecol. 9:63-66. Haas, W. 1964. Verluste von Vogeln und Saugern auf Autostraben. Orn. Mitt. 16:245-250. Hansen, L. 1969. Trafikdoden i den danske dyreverden. Dansk orn. Foren. Tisskr. 63:81-92. Hodson, N. L. 1962. Some notes on the causes of bird road casualties. Bird Study 9(3):168-172. and D. W. Snow. 1965. The road deaths en- quiry, 1960-61. Bird Study 12(2):90-99. Hoz, M. de la. 1982. Algunos datos sobre la alimen- tacion de Athene noctua en Asturias. Bol. C. Nat. IDEA 29:113-120. Labisky, R. F. 1960. A technique for capturing birds and mammals. Biol. Notes No. 40. Nat. Hist. Survey Div., Univ. Illinois. Manez, M. 1983a. Espectro alimenticio de Athene noc- tua en Espana. Alytes 7:275-290. . 1983b. Variaciones geograficas y estacionales de la dieta de Athene noctua en Espana. Actas XV Cong. Fauna Silv. Trujillo 1981. Pp. 617-634. Spencer, K. G. 1965. Avian casualties on railways. Bird Study 12(3):257. Sutton, G. M. 1927. Mortality among Screech Owls (Otus asio) of Pennsylvania. Auk 44:563-564. Val VERDE, J. A. 1967. Estructura de una comunidad de vertebrados terrestres. Consejo Superior de Inves- tigaciones Cientificas, CSIC, Madrid. Weir, D. N. 1971. Mortality of hawks and owls in Speyside. Bird Study 18(3):147-154. Westernhagen, W. 1962. Greifvogel in Andalusien. Orn. Mitt. 1 4(3): 1 62— 1 69. Asociacion para la Defensa de las Estrigiformes Ibe- ricas — ADES, P. Conde de los Gaitanes, 145, La Moraleja, 28109 Madrid, SPAIN. Received 1 February 1988; accepted 15 July 1988 Raptor Protection and Research — Albemarle Farms of Charlottesville, Virginia, in conjunction with Virginia Poly- technic Institute and State University (VPISU) in Blacksburg, is establishing a preserve to be used as a training facility for interns in wildlife management at VPISU. Raptor research and education foundations, along with organizations concerned with the protection of hawks and other migratory birds are invited to make proposals and initiate discussions for cooperative efforts aimed at the development of further techniques for protecting predatory birds. For more information, contact John Williamson, Albemarle Farms, Route 6, Box 69, Charlottesville, Virginia 22901 (804)293- 3978 or Fred Garcia (212)557-0100. J. Raptor Res. 22(3):85-88 © 1988 The Raptor Research Foundation, Inc. Short Communications Nesting of Falco tinnunculus in Natural Sites in Canary Pines on El Hierro Island* Jose Carrillo, Manuel Nogales and Manuel Padron In Europe the reproductive behaviour of the Kestrel {Falco tinnunculus) is similar to that of other Falconidae: no nest building occurs although some individuals scrape the surface where their eggs will be laid (Cave 1968). According to Cramp and Simmons (1980), nesting occurs most frequently in trees, using old nests left by Corvidae (Dementiev et al. 1951), Columbidae (Labitte 1932), Pici- dae (Geroudet 1978), as well as by larger birds of prey, and even in those of arboreal mammals (i.e., Sciurus vul- garis) (Kuusela 1983). The behavioural flexibility of the Kestrel is also shown in its utilization of a wide variety of nesting sites such as ledges on cliffs or building (Geroudet 1978), nest boxes (Cave 1968) and occasionally the ground (Balfour 1955). Use of such varied nest sites is probably one of the factors contributing to the species’ success as the commonest of the diurnal birds of prey in most of the Palearctic and African regions (Cade 1982), including the Canary Is- lands. The reproduction of the Kestrel in the Canary Islands has been discussed, though not in depth (Koenig 1890; Bannerman 1914; Carrillo and Trujillo in press). More- over, studies on the nesting sites are scarce, and lack quan- titative information (Bannerman 1963; Perez Padron 1983), apart from the record of 17 nests on Tenerife (Martin 1987). In the Canary Islands the Kestrel usually breeds in holes and on ledges on cliffs. Nesting in trees is occasional (Cabrera 1893; Polatzek 1908), though in the Eastern Islands nesting in palm trees seems to be a more frequent phenomenon (Meade-Waldo 1889; Bannerman 1963). Other sites where we have also found Kestrel clutches are in walls pertaining to houses and along roadsides, in holes of disused quarries, in old nests of domestic pigeons ( Co - lumba sp.) in rural buildings or earth slopes, and in nests of ravens ( Corvus corax) on rocks, or in Canary Pines (Pinus canariensis). Also, in El Hierro Island the Kestrel breeds normally (approximately 70-80% of cases) in ledges and holes on rocky walls. We have found, however, that on this island * Presented at the IX Jornadas Ornitologicas Espanolas (Madrid, December 1987). the Kestrel breeds in the forests of Canary Pines by laying its eggs on or in the masses of pine needles that accumulate naturally in various parts of mature pine trees. Pine forests on El Hierro Island are characterized by a fairly high density of trees and an almost total lack of undergrowth. Although the forests have been extensively modified by human activities, they contain a substantial number of mature trees, and these are used for nesting by kestrels. Nesting occurred both near the outer borders of the forest and in the interior, apparently without preference. Our observations on El Hierro were carried out during the spring of 1987. The 27 nests that we studied in pine trees were classified according to 7 nest site types (Fig. 1), and distance to the tree trunk and height above ground were also measured. The most frequently utilized sites were the masses of dead pine needles near the ends of lateral branches (Fig. 1, type D). Such accumulations, once initiated, are well situated to catch falling needles from the upper parts of the tree, and thus often reach a large size. The malformations on the tips of the branches (type F), including both living and dead needles, form a more regular type of structure, but in our sample they were used a little less commonly than type D sites. These malformations are sometimes formed at the tops of the trees, and in one there was a small tunnel through which the Kestrel entered to breed. These large and compact foliage concentrations in the tree tops are somewhat com- parable to the bulky nests of the Hamerkop ( Scopus um- bretta) in South Africa, which also has interior tunnels that are occasionally used by nesting kestrels (Steyn 1985). Both type D and type F sites are favourable for nesting, probably because the fragility of the branches is a deterrent to human interference which kestrels often suffer on the islands. The remaining types of nest sites (types A, B, C, D, G) were associated with the trunk and less frequently used by the Kestrel. Accumulations of needles in such sites were usually smaller than those on the branches and may be more vulnerable to human interferences. From a total of 27 nests surveyed the average height from the forest floor surface was 10.3 m (S.D. = 3.15; range = 3-17 m). This height was slightly greater to what Soler et al. (1983) exposed on kestrels nesting on old nests of the Carrion Crow {Corvus corone) on trees in Granada 85 86 Short Communications Vol. 22, No. 3 Autumn 1988 Short Communications 87 (south of the Iberian Peninsula). The average distance from the nests to the tree trunks was 2.9 m (N = 13; S.D. = 2.19; range = 0.5-8 m), a distance similar to that de- scribed by Soler et al. (1983). According to Newton (1979) the density of birds of prey is generally restricted by the availability of breeding sites or food. The high relief of El Hierro, the abundant food supply during the breeding season (Nogales, in prep.) and the versatile feeding habits of the Kestrel on El Hierro Island (Carrillo et al., in press) are all factors that combine to ensure the success of this species on the island. This success probably ensures the saturation of all trophically optimal areas that also contain breeding sites in rocky places (these are in the area of El Pinar). Thus, the use of pine trees for nesting probably increases the overall breeding density of the species on El Hierro. Similar effects have been produced artificially by providing nest boxes (Cave 1968) and artificial nests of Corvidae (Village 1983). It is noteworthy, however, that the use of natural nesting sites in pine trees has not been recorded up to now in any of the other islands in the Canary archipelago. Acknowledgments Guillermo Delgado provided information on the subject. Aurelio Martin and Borja Heredia read and criticized the original manuscript. We are especially grateful to Philip Ashmole for many constructive comments. Literature Cited Balfour, E. 1955. Kestrels nesting on the ground in Orkney. Birds Notes 26:245-253. Bannerman, D. A. 1914. An ornithological expedition to the eastern Canary Islands. Ibis 10(2): 39-90, 228- 293. . 1963. Birds of the Atlantic Islands. Vol I. Oliver & Boyd, Edinburgh. Cabrera, A. 1893. Catalogo de las aves del Archipielago Canario. Anal. Soc. Esp. Hist. Nat. 22:1-70. Cade, T. J. 1982. The falcons of the world. Collins Ltd., London. Carrillo, J. and N. Trujillo (in press). Ponte de remplacement singuliere de Falco tinnunculus canarien- sis (Koenig, 1890). Alauda. , R. Garcia and M. Nogales (in press). Con- tribution a Petude du spectre alimentaire de Falco tinnunculus Linnaeus 1758 dans Pile de El Hierro: Premieres donnees pour les lies Canaries. Alauda. Cave, A. J. 1968. The breeding of the Kestrel Falco tinnunculus L., in the reclaimed area Oostelijk Flevo- land. Netherlands. J. Zool. 18(3):31 3-407. Cramp, S. and K. E. L. Simmons (Ed.). 1980. The birds of the western Palearctic. Vol. II. Oxford Uni- versity Press. Dementiev, G. P., N. A. Gladkov, E. S. Ptushenko, E. P. Spangenberg and A. M. Sudilovskaya. 1951 Birds of the Soviet Union. Vol. I. Z. S. Cole, Ed. Moskva. Geroudet, P. 1978. Les rapaces diurnes et nocturnes d’Europe. Delachaux et Niestle (Ed.). Paris. Koenig, A. 1890. Ornithologische Forschungsergeb- nisse einer Reise nach Madeira und den Canarischen Inseln. J. Orn. 38:257-488. Kuusela, S. 1983. Breeding success of the Kestrel Falco tinnunculus in different habitats in Finland. Proc. Third Nordic Cong. Ornithol. 1981:53-58. Labitte, A. 1932. Reproduction du Faucon Creserelle, Falco t. tinnunculus L. L’Oiseau et la Revue Franc. Or- nith. Martin, A. 1987. Atlas de las aves nidificantes en la Isla de Tenerife (Islas Canarias). Instituto de Estudios Canarios, Consejo Superior de Investigaciones Cien- tificas. Meade- Waldo, E. G. B. 1889. Notes on some birds of the Canary Islands. Ibis 6(1): 1 — 1 3. Newton, I. 1979. Population ecology of raptors. T. & A. D. Poyser, Hertfordshire, England. Nogales, M. (in prep). Biologia del Cuervo, Corvus corax tingitanus en la Isla de El Hierro e importancia en la diseminacion de plantas vasculares en el Archi- pielago Canario. Perez Padron, F. 1983. Las aves de Canarias. Enci- clopedia Canaria. Aula de Cultura del Excmo. Cabildo Insular de Tenerife. Santa Cruz de Tenerife. Polatzek, J. 1908. Die Vogel der kanaren. Orn. Jahrb. 19:161-197. Soler, M. s J. M. ZuNiga e I. Camacho. 1983. Ali- mentation y reproduction de algunas aves de la Hoya de Guadix (Sur de Espana). Trabajos monograficos del Departamento de Zoologia, Universidad de Gra- nada (N.S.) 6(2):27-100. Steyn, P. 1985. Bird of prey of southern Africa. D. Philip (Ed.) Cape Town and Johannesburg. Village, A. 1983. The role of nest-site availability and Figure 1. Diagram showing the different types of nest sites used by Falco tinnunculus in Pinus canariensis on El Hierro, with number of cases and percentages frequency of each type. Types of nest sites shown in the figure are A, nest on trunk hole; B, nest on the trunk ending fork; C, nest on the platform of a main trunk; D, nest on needle accumulation of lateral branches; E, nest on stretched base axillary branch; F, nest on malformation of terminal branch; G, nest on trunk malformation. 88 Short Communications Vol. 22, No. 3 territorial behaviour in limiting the breeding density of Kestrels. J. Anim. Ecol. 52:635-645. Departamento de Biologia Animal (Zoologia-Verte- brados), Facultad de Biologia, Universidad de La Laguna, Tenerife, Islas Canarias, ESPANA. Ad- dress of third author: Calle del Hoyo s/n, El Pinar, El Hierro, Islas Canarias, ESPANA. Received 22 January 1988; accepted 10 August 1988 /. Raptor Res. 22(3):88 © 1988 The Raptor Research Foundation, Inc. Red Fox Predation on Fledgling Egyptian Vultures Jose Antonio DonAzar and Olga Ceballos Reports of predation on nestlings of Old World vultures are rare (see Brown, L. and D. Amadon, Eagles, hawks and falcons of the world. Feltham, Middlesex, 1968; Mun- dy, P., The comparative biology of Southern African Vul- tures. Vulture Study Group, Johannesburg, 1982). The Egyptian Vulture ( Neophron Percnopterus ) nests frequent- ly in narrow cliff cavities where the possibility of mam- malian predation is low (Ceballos, O. and J. Donazar, Munibe, in press). Only one reference (Rodriguez- Jimenez and Balcells, P. Cent. Pir. Biol. Exp. 2:159-187, 1968) reports the capture of a nestling in an accessible nest by a mammalian predator of unknown species. Killing of fledgings by predators are not known. In this note we report an Egyptian Vulture-Red Fox ( Vulpes vulpes ) in- cident and two cases of fledgling predation by Red Foxes. The research was done in Bardenas Reales-Navarra (northern Spain). On 11 August 1987, while observing an Egyptian Vul- ture nest with 2 fledged chicks, we saw a fox approaching the nest along the cliff edge close to where the younger fledgling (81 d old) was perched. Immediately, the female vulture placed herself between the fox and the chick and displayed much nervous excitement. A few seconds after, the fox moved away. Meanwhile, the nestling, very fright- ened, flew hurriedly to a nearby ravine. On 28 August 1987, the remains of an 83 d old fledgling were found under the nest-cliff. On the ground there was a great pool of blood and plucked feathers with cut quills. Fox tracks were very common, and a den was located 150 m away from the nest. On 30 August 1987, a fledgling provided with a radio transmitter flew from the nest at sunset and did not return, roosting on the ground under the nest-cliff. Next morning the young had disappeared. It was 82 d old and its flights were still very short, no more than 50 m around the nest. Searching with receivers we found the radio transmitter together with the nestling remains at the burrow entrance of a fox den, which was 650 m away from the nest. The remains, only wings and body, had signs of carnivore feed- ing. It is difficult to evaluate the real importance of fox predation in our study area. Of 7 fledglings provided with radio transmitters, 1 was killed (last reported case). The chance for predation would be enhanced by foxes wan- dering around vulture nests searching for food remains. Predation seems more probable during the days following the initial flight, which occurs when the chick is around 75 d old. In this period, fledglings are not able to return to the nest at night (unpubl. obs.) and are thus being exposed to possible mammalian predation. Acknowledgments We thank I. Garcia-Bello for assistance in monitoring the nests. F. Hiraldo was the director of the research. S R. Wilbur and P. J. Mundy and an anonymous referee offered constructive criticism on the manuscript. We re- ceived support from the Institute Nacional para la Con- servation de la Naturaleza (Section de Recursos Naturales Renovables). Museo Nacional de Ciencias Naturales, J. Gutierrez Abascal 2, 28006 Madrid, SPAIN. Address of second author: Sociedad de Ciencias Aranzadi, Pi. I. Zu- loaga (Museo), 20003 S. Sebastian, SPAIN. Present address of first author: Estacion Biologica de Don- ana, Pabellon del Paru, Avda M4 Luisa s.n., 41013 Sevilla, SPAIN. Received 27 January 1988; accepted 15 July 1988 Autumn 1988 Short Communications 89 / Raptor Res. 22(3):89 © 1988 The Raptor Research Foundation, Inc. Red-tailed Hawk “Captured” by a Striped Whip Snake Clyde L. Pritchett and James M. Alfonzo During the last 50 yrs, there have been many reports of birds being preyed upon by snakes (Wythe 1933; Austin et al. 1972; Blem 1979). Most reports are of moderate to large snakes preying upon small birds (Ervin and Rose 1973), nestlings (Jackson 1970; Cink 1977) or eggs (Best 1974; 1977), or occasional reports of birds as large as California Quail ( Callipepla californica) killed by “rattle- snakes” (Jewett 1939) and “gopher snakes” (Wythe 1933). Fendley (1980) reported a rat snake consumed several Hooded Merganser ( Lophodytes cucullatus ) eggs in a nest box which also contained a dead female merganser. Whit- field (1934) observed a gopher snake capture a roosting Western Screech Owl (Otus kennicottii). However, we could not find a reference of a snake as small as a Desert Whip Snake ( Masticophis t. taeniatus) capturing a bird as large as an adult Red-tailed Hawk (Buteo jamaicens). On 15 August 1984 a near-dead Red-tailed Hawk was reported to officials at Fish Springs National Wildlife Refuge in western Utah. The hawk was found encoiled by a desert striped whip snake ca. 1 m in length. The snake was wrapped twice around the hawk’s body un- derneath its wings, and once completely around the hawk’s neck rendering it completely incapacitated. After removing the snake from the bird, a careful examination revealed that the hawk had no serious injuries, other than appearing to be in shock. The bird was released at the refuge and after a recovery period of 35 min flew away. Acknowledgments We wish to express our appreciation to Mr. and Mrs. Albert Taylor for their conservation ethic in alerting us to the injured bird and for the photographs they took of this incident. We also thank N. K. Johnson, Curator of Ornithology, M.V.Z., U. C. Berkeley and J. W. Sites, Curator of Reptiles, Department of Zoology, B.Y.U. for their helpful comments and review of the manuscript. Literature Cited Austin, G. T., E. Yensen and C. S. Tomoff. 1972. Snake predation on cactus wren nestlings. Condor 74(4)- 492. Best, L. B. 1974. Blue racers prey on field sparrow nests. Auk 91 (1 ): 1 68—1 69. . 1977. Bull snake preys on rough-winged swal- low nest. Condor 79(4):509. Blem, C. R. 1979. Predation of black rat snakes of a bank swallow colony. Wilson Bull. 91(1):135— 137. ClNK, C. L. 1977. Snake predation on Bell’s vireo nest- lings. Wilson Bull. 89(2):349-350. Ervin, S. and C. Rose. 1973. Gopher snake predation on the common bushtit. Auk 90(3):682-683. Fendley, T. T. 1980. Incubating wood duck and hooded merganser hens killed by black snakes. Wilson Bull 92(4):526-527. Jackson, J. A. 1970. Predation of a black rat snake on yellow-shafted flicker nestlings. Wilson Bull. 82(3):329 Jewett, S. J. 1939. A rattlesnake kills a California quail. Condor 41(1):30. Whitfield, C. J. 1934. A screech owl captured by a snake. Condor 36(2):84. Wythe, M. W. 1933. California quail attacked by go- pher snake. Condor 35(1):34. Department of Zoology, Brigham Young University, Provo, UT 84602. Address of second author: U. S. Fish and Wildlife Service, Fish Springs National Wildlife Refuge, Dugway, UT 84022. Current ad- dress second author, Charles M. Russell National Wildlife Refuge, P.O. Box 166, Ft. Peck, MT 59223. Received 16 January 1988; accepted 15 July 1988 90 Short Communications Vol. 22, No. 3 /. Raptor Res. 22(3):90 © 1988 The Raptor Research Foundation, Inc. First Record of the Mississippi Kite for Bolivia Denice Shaw and Terry C. Maxwell An adult male Mississippi Kite ( Ictinia mississippiensis ) was banded by DS on 6 July 1984 (USFWS #0745- 69057) at a nest in San Angelo, Tom Green Co., Texas. The nest was located in a Mulberry tree ( Morus micro- phylla) near a home in a residential area. On 1 1 November 1986, the kite was shot at San Miguel de Velasco (16°4'S, 61°0'W) Department of Santa Cruz, Bolivia. San Miguel de Velasco is in a region of semihumid lowland forest in eastern Bolivia. The migratory and wintering range of the Mississippi Kite is poorly understood (AOU 1983) but is known to include portions of Central and South America. A band recovery has been reported from Guatemala (Parker 1977) and the species has been collected in Paraguay (Blake 1949) and northern Argentina (Eisenmann 1963; Olrog 1968). The San Miguel de Velasco record is the first confirmation of the species from Bolivia (J. V. Remsen, Jr., pers. comm.; Meyer de Schauensee 1966, 1970; Blake 1977; Mayr and Cottrell 1979) and the first Mississippi Kite band recovery from South America (D. Bystrak, pers. comm.). Acknowledgments We thank J. V. Remsen, Jr. for providing us with his knowledge of Bolivian avifauna and D. Bystrak for pro- viding banding records from the USFWS Bird Banding Laboratory files. Mark Engstrom made helpful comments on the manuscript. Literature Cited American Ornithologists’ Union. 1983. Check-list of North American birds. 6th ed. American Ornithol- ogists’ Union, Washington, DC. Blake, E. R. 1949. Ictinia misisippiensis collected in Par- aguay. Auk 66:82. . 1977. Manual of Neotropical birds. Vol. 1. Univ. Chicago Press, Chicago, IL. Eisenmann, E. 1963. Mississippi Kite in Argentina, with comments on migration and plumages in the genus Ictinia. Auk 80:74-77. Mayr, E. and G. W. Cottrell (Eds.). 1979. Check- list of birds of the world. Vol. 1, 2nd ed. Mus. Comp. Zool., Cambridge, MA. Meyer de Schauensee, R. 1966. The species of birds of South America and their distribution. Livingston Publ. Co., Narberth, PA. . 1970. A guide to the birds of South America. Livingston Publ. Co., Narberth, PA. Olrog, C. C. 1968. Las aves Sudamericanas: Una Guia de Campo. Unid. Nat. Tucuman, Fond. Inst. Miguel Lillo., Tucuman, Argentina. Parker, J. W. 1977. Second record of the Mississippi Kite in Guatemala. Auk 94:168-169. Biology Department, Angelo State University, San An- gelo, TX 76904. Present address of first author: In- stitute of Applied Sciences, University of North Texas, Denton, TX 76203. Received 28 September 1987; accepted 15 July 1988 Autumn 1988 Short Communications 91 /. Raptor Res. 22(3):91 © 1988 The Raptor Research Foundation, Inc. Nocturnal Flight by Turkey Vultures ( Cathartes aura) in Southcentral Texas Stephen P. Tabor and Chris T. McAllister Large flocks of Turkey Vultures ( Cathartes aura) typ- ically gather before nightfall on a single open roost after searching for carrion during the day (Chase 1982). L. Griscom (in Bent 1937) noted that “the vulture is a late riser, seldom being on the wing until an hour after sun- rise.” The following account describes an episode of noc- turnal flight by Turkey Vultures. On 28 September 1985 at 2200 H (CDT) in Real County, Texas, 18.6 km NE of Leakey (elevation 625 m) along Silver Creek, a tributary of the East Frio River, we observed 12 Turkey Vultures gliding, soaring and spiral- ing in characteristic fashion at a height of ca 61 m. Met- erological conditions were: 27°C, full moon, slightly cloudy- overcast sky, intermittent, misty rain, ground wind speed SE 15-20 mph. The birds remained above us for 15-20 min before flying off in a northwesterly direction. As the vultures flew to the NW, we climbed to the top of an adjacent ridge and, with the aid of binoculars, watched the birds fly completely out of visual range (visual con- ditions were excellent due to the full moon) and away from the river and its tributaries. The above observation may represent an unprovoked case of nocturnal flying by Turkey Vultures. On the other hand, it is possible that the birds could have been disturbed from a riverside roost and were simply taking the pre- vailing SE winds away to the NW. However, we believe this is an unlikely explanation due to the following reasons: Prior to dusk, we observed some Turkey Vultures lighting m trees on a roost situated above the river. This roost site was located on the edge of a sheer bluff overlooking the river valley below. It is unlikely that the birds were dis- turbed by human or other intrusion in such an inaccessible location. The following morning at dawn, we again ob- served the birds at a roost (ca 2 km from our original observation post). Because the birds were not marked or followed through the night continually, we can only as- sume that they are the same ones we observed flying at night, as we are quite familiar with the study site and surrounding area. Alternatively, the vultures may have been flying at night to exploit thermals, the sufficient lighting from the full moon or other favorable environmental factors. As pointed out by Kendeigh (1934) and reiterated by Moore (1945), additional information needs to be obtained about the night habits of birds. Although the time of year and location are appropriate, this event was probably not a case of nocturnal migration (K. A. Arnold, pers. comm.). Neither the related Black Vulture ( Coragyps atratus ) nor other New World vultures, are known to migrate at night (Eisenmann 1963). Ober- holser (1974) reported that Turkey Vulture autumnal mi- gratory trips in Texas are carried out entirely diurnally, over a period of 2 wks. In California, Turkey Vultures migrate for a period lasting over 3 mos (96-111 d) from September through November (Binford 1979). However, in Arkansas, Turkey Vultures are still present through mid-December (McAllister, unpubl. observ.) and may not represent birds migrating in from other localities. Acknowledgments We thank K. A. Arnold, C. D. Fisher, and E. L. Hane- brink, for providing information regarding the habits of vultures and J. Coleman, J. R. Parrish, P. Rabenold, G. Warrick, B. Zoellick, and an anonymous referee, for crit- ically reviewing the manuscript. We also appreciate the hospitality of K. Cave, who allowed us to stay at the H. E. Butt Foundation Camp. Literature Cited Bent, A. C. 1937. Life histories of North American birds of prey. Part I. Bull. U.S. Nat. Mus. No. 167. Binford, L. C. 1979. Fall migration of diurnal raptors at Pt. Diablo, California. West. Birds 10:1-6. Chase, A. M. 1982. Choice of roost sites for the night by Turkey Vultures. Bull. N.J. Acad. Sci. 27:26. ElSENMANN, E. 1963. Is the Black Vulture migratory? Wilson Bull. 75:244-249. KENDEIGH, S. C. 1934. The role of environment in the life of birds. Ecol. Monogr. 4:299-417. Moore, A. D. 1945. Winter night habits of birds. Wilson Bull. 57:253-260. Oberholser, H. C. 1974. The bird life of Texas. Vol I. Univ. Texas Press, Austin. Rt. 3, 909 Stella Mae Dr., Burleson, Texas 76028. Ad- dress of second author: Department of Biological Sciences, North Texas State University, Denton, TX 76203. Present address of first author: 3620 Caldwell, Bakersfield, CA 93309. Received 6 January 1988; accepted 1 June 1988 92 Short Communications Vol. 22, No. 3 J. Raptor Res. 22(3):92 © 1988 The Raptor Research Foundation, Inc. Incidence of Black-phase Plumage in Ferruginous Hawks Nesting in Central North Dakota Paul M. Konrad and David S. Gilmer Distinct plumage phases for the Ferruginous Hawk (. Buteo regalis) include normal, black and red (Brown and Amadon 1968). During a three-yr (1977-79) study of nesting Ferruginous Hawks in central North Dakota (Gil- mer and Stewart 1983), we observed only normal and black-phase plumage in adults and in nestlings with well- developed plumage. A total of 12 (1.1%) of 1050 adult Ferruginous Hawks we observed at nest sites had black-phase plumage. The number of nest sites occupied by black-phase adults was five of 200 (3%) in 1977, five of 184 (2.7%) in 1978 and two of 245 (0.8%) in 1979 (Table 1). All black-phase adults were paired with normal-colored mates, and mixed pairings produced broods that varied from all black to all normal. Sixteen (47%) of 34 mixed-pair nestlings had black-phase plumage. In addition one black nestling was produced by a normal pair. Only 17 (1.2%) of 1407 nest- lings we observed had black-phase plumage. Observations of one mixed pair and its broods are es- pecially noteworthy. A pair consisting of a black-phase Table 1. Plumage characteristics of adults and nestlings at nest sites occupied by black color phase Fer- ruginous Hawks in central North Dakota. Year No. Black Adults No. Black Nestlings No. Normal Nestlings 1977 1 2 1 1 2 3 0 a 1 2 1 0 4 1 0 1 1 b b 1978 1 1 2 1 1 2 1 1 3 1 3 1 1 b b 1979 1 3 0 1 3 1 Total 12 17 20 a Only normal-phase adults observed at nest site. b Nesting attempt failed. No brood information. female and a normal-colored male was observed for five consecutive yrs (1977-81) at the same nest site. During this period, five broods were produced which contained zero of four, one of four, three of three, one of two, and two of four black-phase nestlings. Our data indicate that, compared with most other re- gions, adult black-phase Ferruginous Hawks are relatively rare breeders in central North Dakota. The incidence of Ferruginous Hawks with black plumage reported in other regions was 9.4% in southeastern Alberta (Schmutz and Schmutz 1981), 5.7% in southeastern Washington (Fitzner et al. 1977), about 4% in southern Idaho (Howard 1975; Thurow et al. 1980), 3% in northeastern Colorado (Olen- dorff 1973) and <1% in northcentral South Dakota (Loke- moen and Duebbert 1976). Literature Cited Brown, L. H. and D. Amadon. 1968. Eagles, hawks, and falcons of the world. McGraw-Hill, New York. 2 vols. 945 pp. Fitzner, R. E., D. Berry, L. L. Boyd and C. A. Rieck. 1977. Nesting of Ferruginous Hawks ( Buteo regalis) in Washington 1974-75. Condor 79:245-249. Gilmer, D. S. and R. E. Stewart. 1983. Ferruginous Hawk populations and habitat use in North Dakota. J. Wildl. Manage. 47:146-157. Howard, R. P. 1975. Breeding ecology of the Ferru- ginous Hawk in northern Utah and southern Idaho. M.S. thesis, Utah State Univ., Logan. 59 pp. Lokemoen, J. T. and H. F. Duebbert. 1976. Ferru- ginous hawk nesting ecology and raptor populations in northern South Dakota. Condor 78:464-470. Olendorff, R. R. 1973. The ecology of the nesting birds of prey of northeastern Colorado. U.S. Int. Biol. Programme Grassland Biome Tech. Rep. 211. 233 pp. Schmutz, S. M. and J. K. Schmutz. 1981. Inheritance of color phases of Ferruginous Hawks. Condor 83:187- 189. Thurow, T. L., C. M. White, R. P. Howard and J F. Sullivan. 1980. Raptor ecology of Raft River Valley, Idaho. U.S. Dep. Energy, Idaho Natl. Eng. Lab., Natl. Tech. Inf. Serv., Springfield, VA. 45 pp. U.S. Fish and Wildlife Service, Northern Prairie Wild- life Research Center, Jamestown, ND 58402. Pres- ent address of first author: 418-18 Street, Bismarck, Autumn 1988 Short Communications 93 ND 58501. Present address of second author: Wild- Received 7 April 1988; accepted 30 August 1988 life Research Field Station, U.S. Fish and Wildife Service, 6924 Tremont Road, Dixon, CA 95620. /. Raptor Res. 22(3):93 © 1988 The Raptor Research Foundation, Inc. Great Horned Owl Observed “Hawking” Insects James R. Duncan and Patricia A. Lane On 20 October 1986 at 1848 H we observed a Great Horned Owl ( Bubo virginianus ) perched atop one of many snags in a flooded bog alongside a forestry fire road of the Sandilands Provincial Forest, Manitoba, Canada. A sec- ond Great Horned Owl was perched approximately 30 m distant. The “pair” maintained vocal contact intermit- tently, which suggested that the second owl was a male, having a lower pitched call (Austing, G. R. and J. B. Holt. The world of the Great Horned Owl. Lippincott Co., 1966). The male made several short flights of varying heights (one to four m) over the bog and returned to the same perch or one nearby. These occurred during the first 30 of the 45 min we observed the owls. Using a 45x spotting scope we observed the male owl consuming large beetle- like insects while perched. The beetles were most likely Dytiscus sp. which were observed to emerge from a ditch adjacent to the fire road with an audible “plop,” and the hum of their wings could be heard up to 5 m away. The male caught at least five beetles in his bill during observed “hawking” flights, but the female was not observed to do so. However, at 1918 H both birds landed on the fire road and consumed live beetles. At 1933 H there was insuffi- cient light to continue observations. Our observed “insect hawking” provides further evi- dence of the opportunistic feeding behavior of this gen- eralist owl. Remains of at least four genera of beetles, including Dytiscus and other invertebrates, have been found in Great Horned Owl pellets (Hamerstrom and Mattson, Am. Midi. Nat. 22(3):700-702, 1939; Errington et al., Iowa Agric. Exp. Stn. Res. Bull. 277:758-850, 1940; Bent, A. C., Life histories of North American birds of prey, Part II. U.S. Nat. Mus. Bull. 162, Washington, DC. 1961). Errington et al. (1940) could not conclude if insects were eaten directly by owls or consumed along with the stomach contents of other prey. Where insects were undoubtedly owl prey they are considered conspicuous crawlers, carrion feeders or predators, etc., attracted to carcass fragments about feeding places (Errington et al. 1940). Errington et al. (1940) also explained insect fragments in pellets as reflecting the partial dependence of inexperienced young owls upon types of prey that are easy to catch, including invertebrates. Our observation provides evidence that di- rect captures of flying insects may explain the occurrence of some of the insect matter found in Great Horned Owl pellets. Insect foraging would be more economical ener- getically for smaller sized males with greater aerial ma- neuverability (Mueller, H. C., Wilson Bull. 98(3):387- 406, 1986), although both sexes were observed consuming insects on the ground. Thanks to D. M. Bird, N. Gard and R. W. Nero for helpful comments on the manuscript. 219 Berry Street, Winnipeg, Manitoba R3J 1N3, CAN- ADA. Received 10 March 1987; accepted 31 August 1987 /. Raptor Res. 22(3):94- 95 © 1988 The Raptor Research Foundation, Inc. Dissertation Abstracts Winter Territoriality and Predation Ecology of American Kestrels ( Falco sparverius) in Southcentral Florida Migrant American Kestrels {Falco sparverius) wintering in southcentral Florida showed marked segregation of sexes due to differential habitat use. Females typically occupied territories in pastures, mowed hayfields and recently planted citrus groves. Males were observed primarily along the margins of slash pine ( Pinus elliotii) woodlots, eucalyptus {Eucalyptus spp.) plantations and cypress {Taxodium distichum ) sloughs, and within scrubby flatwoods, mature citrus groves and residential areas. Although most males were found in less open habitats, both sexes foraged in open patches of the same type of hunting substrate, grasses or weedy forbs <25 cm in height (herein, suitable hunting substrate). Pellet analysis revealed that both sexes fed exclusively on arthropods. Male and female territories differed in the proportion of area covered by suitable hunting substrate (median values of 0.30 and 0.60, respectively). Additionally, more numerous and larger trees or shrubs characteristic of male territories formed a visual barrier such that a smaller proportion of the available hunting substrate was visible from any one perch. Differential prey availability was evident from differences between male and female activity budgets. Males were similar to females in capture success, once a prey item was detected, and in the total number of prey items captured per day. However, most males were constrained to forage actively throughout the entire day while females were able to satisfy most of their daily food requirements earlier in the day and thus had a substantial amount of time remaining to allot toward nonforaging activities. In addition males were more likely to attack novel prey items and experienced a greater loss of body mass during a period when ambient temp <0°C reduced arthropod prey availability. The evidence supports the hypothesis that most female territories were of superior foraging quality. Kestrels wintering in the study area were captured in order to collect their pellets. Dry mass of pellets was used as an index of accumulated mass of prey consumed between dawn, when pellets representing prey consumed the previous day had been regurgitated, and time of capture. Kestrels holding territories of superior foraging quality (those with > 50% coverage by suitable hunting substrate) consumed a greater prey mass during morning than did kestrels inhabiting territories of lesser foraging quality. No difference was found between territories of high and low foraging quality in terms of the total prey mass consumed by the end of the day. Most territories of high foraging quality were occupied by females, but within habitats of either high or low foraging quality, the temporal patterns of prey mass accumulation by males and females were similar. These results are consistent with observed kestrel activity budgets, and lend further support to the hypothesis that the temporal differences in foraging behavior between males and females were due to differences in the foraging quality of their territories; there was no evidence of any inherent sex-specific differences in predatory behavior. The foraging quality of kestrel winter territories in the study area was a function of the extent to which locations were covered by patches of a particular foraging substrate. The establishment of 240 winter territories by kestrels on a 293-km census route in the study area was observed during autumn 1985. Most females arrived before males. Analysis of 18 367 USFWS records of kestrels banded during autumn in eastern North America revealed that immatures of both sexes and adult females preceded adult males in migration, thus skewing the sex ratio of early arrivals toward females. In the south Florida study area territorial kestrels occupied habitats in decreasing order of foraging quality, as measured by percent cover of suitable hunting substrate and by woody canopy cover (which was negatively correlated with suitable hunting substrate and obstructed the view of a hunting kestrel). Although most females arrived first, early-arriving males also occupied habitats of superior foraging quality and were as successful as females in defending territories against same-sex and opposite-sex kestrels as space in high quality habitats became limited. There was no evidence that a kestrel of either sex, once established, was ever displaced by a later- arriving conspecific. Results of experiments in which free-flying intruder kestrels were released into defended territories suggest that males, which typically held territories with smaller surpluses of prey resources and therefore stood to suffer more from an intrusion by a food competitor, defended winter territories more tenaciously than did females. Because there was no evidence of male submissiveness on wintering grounds, a female dominance hypothesis is not a plausible explanation for sexual segregation by habitat in wintering kestrels Each kestrel’s arrival date was apparently the principal determinant of which habitats were still available for occupancy, foraging quality was negatively correlated with arrival date for both adult males and for females and immatures. Delayed molt in adult males, associated with differential sex roles on breeding grounds, may result in delayed migratory departure and thus late arrival onto wintering grounds. An examination of relative importance of three prey characteristics, size, color and activity, with respect to prey selection by wild kestrels wintering in the study area was conducted using House Mouse {Mus musculus ) as prey. Results suggest that prey activity was more important than either prey size or prey coat color with respect to selection 94 Autumn 1988 Thesis Abstracts 95 by kestrels. Active prey were selected more often apparently because they were more easily detected. Although conspicuous coloration did not appear to enhance detectibility of prey in the present study, conspicuousness may be important in prey detection under certain environmental conditions. Smallwood, John A. 1987. Ph.D. Dissertation. Department of Zoology, The Ohio State University, Columbus, OH 43210, U.S.A. /. Raptor Res. 22(3):95 © 1988 The Raptor Research Foundation, Inc. Thesis Abstracts Behavioral Development of Young Golden Eagles at a Hack Site: A Comparison to Wild Eaglets A project was begun in 1981 to establish a breeding population of Golden Eagles ( Aquila chrysaetos) in the southern Appalachians by hacking captive produced young near the Shining Rock Wilderness Area in Haywood County, North Carolina. The study attempted to determine behavioral differences between wild and hacked eaglets. Performance levels of 35 “key” behaviors were quantified and entered into an electronic data recorder, allowing data to be analyzed by computer. Behavioral performance levels of hacked eaglets were statistically compared to wild eaglets (Ellis 1973) by i-Tests. Some behavioral differences seem to be due to the effect of hacking (e.g., lower bout numbers for postures and higher Flap and Spread-hold performances), while other differences seem to be caused by abnormal physical development (e.g., slow transition from Lie to Stand and higher performance levels of Preening). Alternate hacking methods and uses of behaviors as indicators of proper development are discussed. Roberts, Dan Allan, 1985. M.Sc. Thesis (under the direction of Dr. Richard D. Brown), Department of Biology, The University of North Carolina at Charlotte, Charlotte, NC 28216. News and Reviews Chevron Conservation Awards Program and 1988 Honorees. The Conservation Awards Program is the oldest privately-sponsored program of its kind in the United States. Founded in 1954 by Ed Zern, the program has been sponsored by Chevron since 1986. Anyone in the United States or Canada can nominate an individual or a nonprofit organization for a Conservation Award. An independent committee of distinguished conservationists, representing a variety of conservation activities in North America, evaluates the nominees. From this list, the panel and Ed Zern select ten volunteer citizens, ten professionals and five nonprofit organizations. Honorees receive $1000 and a bronze plaque in honor of their conservation achievements. Among the 1988 honorees were Gerald R. Craig of the Colorado Division of Wildlife Resources for his work in the Peregrine Falcon recovery program in the western United States, and Hope Carpenter who is director of the Pennsylvania Raptor Association and has led a 20-year campaign to gain public awareness and acceptance of avian wildlife. For further information on nominating procedures for 1989 contact W. C. Roper, Corporate Program Director, Chevron Conservation Awards, P.O. Box 7753, San Francisco, CA 94120-7753; Telephone (415) 894-2457. 1989 Annual Meeting of The Raptor Research Foundation, Inc. — A joint meeting of The Raptor Research Foundation, Inc., and the ICBP World Working Group of Birds of Prey will take place 8-14 October 1989 at the Hotel Mocambo in Veracruz City, Veracruz, Mexico. Approximate costs will be $420.00 U.S. for single and $300.00 U.S. for double occupancy, including breakfast and dinner. Major themes of the joint meeting will be Biology and Conservation of Tropical Raptors. Mario A. Ramos is Chairman of the Local Committee. All individuals interested to attend should write to Mr. Romeo Dominguez Barradas, Local Arrangement Committee, RRF/WWGBP Meeting INIREB, P.O. Box 63, Xalapa, Veracruz, 91000 MEXICO. Those requesting additional information will receive the formal meeting announcement and the call for papers. THE RAPTOR RESEARCH FOUNDATION, INC. (Founded 1966) OFFICERS PRESIDENT: Gary E. Duke SECRETARY: James D. Fraser VICE-PRESIDENT: Richard J. Clark TREASURER: Jim Fitzpatrick BOARD OF DIRECTORS EASTERN DIRECTOR: Keith Bildstein CENTRAL DIRECTOR: Patrick T. Redig MOUNTAIN & PACIFIC DIRECTOR: W. Grainger Hunt EAST CANADA DIRECTOR: David M. Bird WEST CANADA DIRECTOR: Lynn Oliphant INTERNATIONAL DIRECTOR: Bernd Meyburg DIRECTOR AT LARGE #1: Michael Collopy DIRECTOR AT LARGE #2: Gary Duke DIRECTOR AT LARGE #3: Jeffrey L. Lincer 4ea|e9fe9|e4s3fe3{c?{c^ea|c^c^c9|c>|csfte>|ca|e3|e9Cea|: EDITORIAL STAFF EDITOR: Jimmie R. Parrish, Department of Zoology, 159 Widtsoe Building, Brigham Young Uni- versity, Provo, Utah 84602 ASSOCIATE EDITORS Reed Bowman — Behavior Susan Chaplin — Anatomy and. Physiology Richard J. Clark — Order Strigiformes JEFFREY L. Lincer — Environmental Chemistry and Toxicology Carl Marti — Ecology Patricia P. Rabenold — New World Vultures Patrick T. Redig — Pathology, Rehabilitation and Reintroduction Sanford R. Wilbur — Old World Vultures INTERNATIONAL CORRESPONDENT: Richard J. Clark, York College of Pennsylvania, Coun- try Club Road, York, Pennsylvania 17405 The Journal of Raptor Research is distributed quarterly to all current members. Original manuscripts dealing with all aspects of general ecology, natural history, management and conservation of diurnal and nocturnal predatory birds are welcomed from throughout the world, but must be written in English. Contributors should submit a typewritten original and three copies of text, tables, figures and other pertinent material to the Editor. Two original copies of photographic illustrations are required. All submissions must be typewritten double-spaced on one side of 8 Vz x 11 -inch (21 Vi x 28 cm) good quality, bond paper. Number pages through the Literature Cited section. The cover page should contain the full title and a shortened version of the title (not to exceed 30 characters in length) to be used as a running head. Author addresses are listed at the end of the Literature Cited section. Provide an abstract for each manuscript more than 4 double-spaced typewritten pages in length. Abstracts are submitted as a separate section from the main body of the manuscript and should not exceed 5% of the length of the manuscript. Both scientific and common names of all organisms are always given where first appearing in the text and should conform to the current checklists, or equivalent references, such as the A.O.U. Checklist of North American Birds (6th ed., 1983). Authors should ensure that all text citations are listed and checked for accuracy. If five or fewer citations appear in the text, place the complete citation in the text, following these examples: (Brown and Amadon, Eagles, Hawks and Falcons of the World. McGraw-Hill, New York, 1968), or Nelson {Raptor Res. 16(4):99, 1982). Metric units should be used in all measurements. Abbreviations should conform with the Council of Biology Editors (CBE) Style Manual, 5th ed. Use the 24-hour clock (e.g,, 0830 and 2030) and “conti- nental” dating (e.g., 1 January 1984). A more detailed set of instructions for contributors appeared in J. Raptor Res., Vol. 21, No. 1, Spring 1987, and is available from the Editor. Send all manuscripts for consideration and books for review to the Editor.