RAPTOR RESEARCH Volume 1.1 Nmnlier 4 Winter 19TO R;ipLi>i R^wardi Foundation* Irtc. Provo, Utah, LLS,A. RAPTOR RESEARCH Winter 1979 Volume 13 Number 4, Pages 97-128 CONTENTS SCIENTIFIC PAPERS Distances Between Birthplace and Breeding Place in Sparrowhawks and Other European Raptors— I. Newton 97 Decomposition of Raptor Pellets— James R. Philips and Daniel L. Dindal 102 Observations on the Behavior of Wintering Bald Eagles— Howard I. Russock 112 Use of Hunting Methods by Ferruginous Hawks in Relation to Vegetation Density— James S. Wakeley 116 Coopers Hawk Attacks Sharp-tailed Grouse— D. L. J. Moyles 120 Subterranean Nesting by Prairie Falcons— Bruce A. Haak and S. Jon Denton 121 Red-tailed Hawk Preys on Adult Sage Grouse in Northern Utah— Cal McCluskey 123 ANNOUNCEMENTS 124 ABSTRACTS 125 BOOK REVIEWS 126 RAPTOR RESEARCH Published Quarterly by the Raptor Research Foundation, Inc. Editor Dr. Clayton M. White, Dept, of Zoology, 161 WIDB, Brigham Young University, Provo, Utah 84602 Editorial Staff Dr. Frederick N. Hamerstrom, Jr. (Principal Referee) Dr. Byron E. Harrell (Editor of Special Publications) The Raptor Research Foundation, Inc., welcomes original articles and short notes concerning both diurnal and nocturnal birds of prey. Send all papers and notes for publication and all books for review to the Editor. Most longer articles (20 or more typeset pages) will be considered for publication in Rap- tor Research Reports , a special series for lengthy and significant contributions containing new knowledge about birds or new interpretations of existing knowledge (e.g., review articles). However, authors who pay page costs (cur- rently $20.00 per page) will expedite publication of their papers, including lengthy articles, by ensuring their inclusion in the earliest possible issue of Raptor Research. 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DISTANCES BETWEEN BIRTHPLACE AND BREEDING PLACE IN SPARROWHAWKS AND OTHER EUROPEAN RAPTORS b y I. Newton Institute of Terrestrial Ecology Monks Wood Experimental Station Abbots Ripton, Huntingdon PE 17 2LS, England Abstract Raptors that have been studied tended to settle and breed in the neighbourhood where they were born, and band recoveries (and hence dispersed birds) fell off expo- nentially in successive circles out from the birthplace. Within species, geographical or annual differences in dispersal distances occurred, probably dependent on the distri- bution of food sources and of vacant territories. Individuals in some irruptive popu- lations tended to disperse further than those in other populations. In European Spar- rowhawks and Hobbies, females dispersed further on average than did males. Introduction The question of how far raptors disperse from their birthplace to their subsequent breeding place is relevant both to population theory and to conservation. In this pa- per I shall summarize some information on this point from European banding schemes. For any such analysis, recoveries come mainly from members of the public, and the assumption usually has to be made that any bird of appropriate age reported in the breeding season was in fact nesting at the locality concerned. I took care to separate the immatures, for ringing has already shown that these birds may summer in partly different areas from the breeding adults of their popu- lation. So far at least three such traits have emerged: (1) the immatures may remain all summer in “winter quarters,” e.g., first-year Steppe Buzzard (. Buteo b. vulpinus ); (2) they may migrate north later and spend less time on the breeding areas than adults, e.g., Broad-winged Hawk ( B . platypterus ); or (3) they may migrate north but stop short of the breeding areas, e.g., second-year Osprey ( Pandion haliaetus ) (Olsson 1958, Osterlof 1951, Matray 1974, Schifferli 1965). Moreover, different populations of a species may behave in different ways, as may the different age-groups among the nonbreeders of a single population. In the Osprey, most recoveries of yearlings in summer come from the “winter quarters,” most recoveries of second-year birds are from further north but not as far as the breeding areas, and only in later years are most recoveries from the breeding areas themselves. This pattern holds in both the Old World and the New (Osterlof 1951, 1977; Henny & van Velzen 1972). In the Black Kite ( Milvus migrans), which migrates from Europe to Africa, a more pro- tracted pattern is found, as the majority of summer recoveries come from progressive- ly nearer the birthplace from the first to the fourth and later years (Shifferli 1967). In several migrant species, occasional adults are reported in summer on “winter quar- ters.” In the literature it is usually assumed that these birds are skipping a breeding attempt rather than nesting far to the south of their usual range. 97 Raptor Research 13(4):97-101 98 RAPTOR RESEARCH Vol. 13 No. 4 Sparrowhawk It is convenient to start with the European Sparrowhawk (Accipiter nisus ) because more records are available for this than for ay other raptor. The species is non- migratory in Britain, and, when the young become independent in August, they dis- perse outwards in various directions from the nest (Newton 1975). They begin breed- ing in their next summer or the one after, in their first or second year. The breeding season recoveries of this species were mostly clustered around the birthplace and became sparser with increasing distance (fig. 1). Thus about 76% of 201 recoveries were within 20 km of the birthplace, and almost all were within 50 km. Treating all the recoveries together, their density fell off exponentially in con- centric circles out from the birthplace, a drop of about 99% between the 0-5 km zone and the 21-25 km zone. This pattern was established by the first autumn and hardly changed thereafter, implying that in this species most birds dispersed within a few weeks of fledging to near where they would later breed. I therefore included all first-year birds in the analysis just described, even though some of them may not have nested. Other Species The breeding season recoveries of other raptors also thin out with increasing dis- tance from the birthplace, but at different rates in different species. A circle drawn at 50 km round the birthplace would include 98% of breeding season recoveries of the British Sparrowhawk, 89% of the British Kestrel (Falco tinnunculus ), 75% of the British Merlin ( Falco columharius ), 71% of the Swedish Goshawk (. Accipiter gentilis), 62% of the German Buzzard ( Buteo huteo), and 43% of Fennoscandian Ospreys of breeding age (table 7). Using data from the European and Soviet ringing schemes, Galushin (1974) calculated the mean distance between birthplace and presumed breeding place for eleven raptor species. This distance was much greater in some of the irruptive species, which depended on sporadic food sources, than in the others. Table 1. Dispersal of Some European Raptors from Birthplace to Presumed Breeding Place. Species (region, number) % of all breeding season band recoveries within Reference following distances (km) from birthplace 20 50 100 200 500 Osprey (Fennoscandia, 79) p 43 59 67 77 Osterlof 1977 Black Kite (Switzerland, 11) ? p 91 ? 100 Schifferli 1967 Goshawk (Sweden, 55) 31 71 84 93 98 Hoglund 1964 Sparrowhawk (Britain, 201) 76 98 99 100 100 B.T.O, records Buzzard (Britain, 15) 73 93 100 100 100 B.T.O records (Germany, 45) ? 62 ? 98 100 Mead 1973 (Denmark, 10) 30 60 80 100 100 Nielsen 1977 (Fennoscandia, 15) 67 95 100 100 100 Olsson 1958 Kestrel (Britain, 18) 61 89 89 100 100 Snow 1968 (Holland, 150) ? 63 80 93 100 Cave 1968 (Switzerland, 35) ? 43 46 51 91 Schifferli 1965 Merlin (Britain, 16) 38 75 81 100 100 Mead 1973° 0 Hobby (Germany, 12)° 92 100 100 100 100 Fiuczynski 1978 Note: ‘Probably all males, females disperse further; "amplified by letter, Winter 1979 Newton— Distances in Raptors 99 The most extreme was the Rough-legged Buzzard (. Buteo lagopus), with a mean dis- persal distance of nearly 2,000 km (number of recoveries was not given). Within species, geographical trends occurred, which accorded with regional differ- ences in the stability of food sources. Mean distances between birthplace and breed- ing place were longer for the Kestrel (277 ± 57) and Common Buzzard (295 ± 105) in northern and eastern Europe than they were in western and central Europe (146 ±59 and 60 ±11 km), and longer still than they were in Britain (Galushin 1974, table 1). Among Goshawks in northern Europe, movements were longer in poor food years than in good ones (Haukioja & Haukioja 1970). Presumably birds had to search fur- ther, on average, in poor food conditions than in good ones until they found vacant areas with sufficient food. Sex Differences In two species, dispersal between birthplace and breeding place could be examined separately for the sexes, and in both species females moved farthest. In the Spar- rowhawk this was evident from the British ring recoveries, in which two-thirds of males had moved less- than 10 km from their birthplace, and two-thirds of females had moved more than 10 km (table 2). In the Hobby ( Falco subbuteo), it was evident from a local study near Berlin, in which 85% of 180 male Hobbies seen breeding had been raised in the area, compared with only 11% of 174 females (P< 0.001). As the Table 2. Sex Difference in the Dispersal Distances of British Sparrowhawks between Birthplace and Presumed Place of First Breeding, Dispersal distance Less than 10 km More than 10 km Males 20 11 Females 9 20 Significance of difference, x 2 = 6,7, P<0.01 Figure 1. Breeding season recoveries of ringed Sparrowhawks showing distance of recovery from birthplace, which is represented by the center of the circle at the cross lines. sex ratio among nestlings ringed in the area was about equal, this difference implied a much greater fidelity to birthplace among males than among females (it was too great to be due to differential mortality) (Fiuczynski 1978). Such sex differences in dispersal may occur because males and females are exposed to different ecological conditions, or they may be inherent, perhaps serving to reduce inbreeding. Thus de- spite the many intensive studies that have been made of colour-ringed populations of other birds, hardly any brother-sister or parent-child matings have been recorded, and when they did occur, they were less successful than matings between unrelated indi- viduals (Lack 1954, Greenwood et al. 1978). Acknowledgments I am grateful to the British Trust for Orinithology for use of ringing data, and to the Nature Conservancy Council for financing part of this work. Literature Cited Cave, A. J. 1968. The breeding of the Kestrel, Falco tinnunculus L., in the reclaimed area Oostelijk Flevoland. Netherlands J. Zool. 18:313-407. Fiuczynski, D. 1978. Zur Populationsokologie des Baumfalken ( Falco subbuteo L., 1758). Zool Jb. Syst Bd. 105:193-257. 100 RAPTOR RESEARCH Vol. 13 No. 4 Galushin, V. 1974. Synchronous fluctuations in populations of some raptors and their prey. Ibis 116:127-34. Greenwood, P. J., Harvey, P. H., and Perrins, C. M. 1978. Inbreeding and dispersal in the Great Tit. Nature 271:52-4. Henny, C. J., and van Velzen, W. T. 1972. Migration patterns and wintering local- ities of American Ospreys. J. Wild 'l. Manage. 36:1133-41. Hoglund, N. 1964. Der Habicht Accipiter gentilis Linne in Fennoscandia. Viltrevy 2:195-270. Lack, D. 1954. The natural regulation of animal numbers. Oxford: Clarenden. Matray, P. F. 1974. Broad- winged Hawk nesting and ecology. Auk 91:307-24. Mead, C. J. 1973. Movements of British raptors. Bird Study 20:259-86. Newton, I. 1975. Movements and mortality of British Sparrowhawks. Bird Study 22:35-43. Nielson, B. P. 1977. Migratory habits and dispersal of Danish Buzzards Buteo buteo. Dansk Orn. Foren. Tidsskr. 71:1-9. Olsson, O. 1958. Dispersal, migration, longevity and death causes of Strix aluco, Buteo buteo, Ardea cinerea and Larus argentatus. Acta Vertebratica 1:91-189. Osterlof, S. 1951. Fiskgjusens, Pandion haliaetus (L), flyttning. Var F&gelv&rld 10:1-15. Osterlof, S. 1977. Migration, wintering areas, and site tenacity of the European Os- prey Pandion h. haliaetus (L). Ornis Scand. 8:61-78. Schifferli, A. 1965. Vom Zugverhalten der in der Schweiz brutenden Turmfalken Fal- co tinnunculus, nach den Ringfunden, Orn. Beob. 62:1-13. Schifferli, A. 1967. Vom Zug Schweizerischer und Deutscher Schwarzer Milane nach Ringfunden. Orn. Beob. 64:34-51. Snow, D. W. 1968. Movements and mortality of British Kestrels Falco tinnunculus. Bird Study 15:65-83. No. RECOVERIES PER lOOO KM 2 Winter 1979 Newton— Distances in Raptors 101 E DECOMPOSITION OF RAPTOR PELLETS by James R. Philips and Daniel L. Dindal Department of Forest Zoology State University of New York College of Environmental Science and Forestry Syracuse, New York 13210 Abstract Decomposing pellets from Great Horned Owls were studied during the summer and fall of 1973. After four months, pellets weighed 38-89 percent of their initial dry weight. Thirteen species of fungi were isolated from the pellets. Funnel extraction yielded 3,665 invertebrates from 75 pellets. The most important invertebrates in pel- let decomposition appear to be the trogid beetles and the tineid moths. Raptor pel- lets serve as a feeding, breeding, and shelter site for many invertebrates, including predators, parasites, fungivores, and saprovores. Introduction Indigestible material is quite commonly regurgitated by birds in the form of roughly oval to cylindrical pellets. Such regurgitation is known to occur in 330 spe- cies in more than 60 families, according to a survey made by The International Bird Pellet Study Group (Glue 1973). Among them are such birds as jays, flycatchers and thrushes, as well as hawks and owls (Simmons 1973, Tucker 1944). Raptor pellets generally consist of fur, feathers, bone, scales, chitin, and other prey remains, densely packed and held together by mucus secreted from the digestive tract which dries and hardens soon after egestion. In some cases, pellets of wax (Honey Buzzard, Pernis api- vorus , Meinertzhagen 1959) or even soil (Kestrel, Falco tinnunculus, Davis 1975) may be found. Pellets are also ejected by other vertebrates, including some mammals, rep- tiles, and amphibians (Hanson pers. comm., Dobroruka 1973). Pellets provide data on avian food habits and prey populations, but many other as- pects are of interest as well. Smith and Richmond (1972), Duke et al. (1973, 1975, 1976), and others have examined the physiology of pellet formation and regurgitation. Dobrokhotov and Litvin (1971) studied time-related dynamics of Kestrel pellet forma- tion by measuring pellet radioactivity after the raptor ingested mice containing P 32 . Raptor pellets may also play a role in the spread of diseases such as sylvatic plague, since they are temporarily infective if diseased prey has been eaten (Jellison 1939). Plague antigens can be detected much longer than the plague microbe itself in pel- lets, and pellet analysis has been proposed as one of the best methods of detecting epizootic plague infestations (Lobachev et al. 1971, Lobachev and Shenbrot 1974). Pellet decomposition has been given very little attention. Some authors have re- ported that pellets may remain intact for many years (Brooks 1929, Prestt and Wag- staffe 1973). Others have found that pellets are broken down in weeks or months (Wilson 1938, Marti 1974). Watling (1962, 1963) studied fungal succession on Kestrel 102 Raptor Research 13(4): 102-1 11 Winter 1979 Philips & Dindal— Raptor Pellets 103 (Falco tinnunculus) pellets and isolated 51 species of fungi and one alga. Hubalek (1974) isolated many fungal species from owl pellets. The invertebrate fauna reported from pellets is limited to a few insects (table 1). Therefore, the objective of this re- search was to elucidate the invertebrate microcommunity associated with decomposi- tion of owl pellets. The concept of microcommunity as presented by Dindal (1973a) was assumed in the study. Table 1. Insect Fauna of Raptor Pellets Order Family References Coleoptera Dermestidae Carpet beetles Dermestes spp. Silphidae Carrion beetles Trogidae Skin beetles Trox erinaceous J. Lee. Trox foveicollis Harold Trox plicatus Robinson Trox scaber (L.) Trox spinulosus simi Robinson Trox striatus Mels. Trox variolatus Mels. Diptera Anthomyiidae Anthomyid or latrine flies Fannia aerea (Zetterstedt) Hijdrotaea occulta (Meigen) Scatophagidae Manure-feeding flies Scatophaga squalida Meigen Scenopinidae Window flies Scenopinus sp. Hymenoptera Braconidae Braeonid parasitoid wasps Phaenocarpa ruficeps (von Es.) Lepidoptera Tineidae Clothes moths Monopis ferruginella (Hubner) Monopis rusticella (Clerck) Monopis weaverella Scott Tinea pellionella (L.) Tineola bisselliela (Hummel) Trichophaga sp. Trichophaga tapetzella (L.) Wallace, 1948 Simmons, 1971 Hanson, pers. comm. Petersen, 1960 Davis, 1909 Vaurie, 1955 Vaurie, 1955 Davis, 1909 Vaurie, 1955 Vaurie, 1955 Dillon and Dillon, 1972; Vaurie, 1955 Aubrook, 1939 Aubrook, 1939 Aubrook, 1939 de Joannis, 1899 Aubrook, 1939 Morton et al, 1977; Vernon, 1972 Hinton, 1956 Nurse, 1906; Buxton, 1914; Elton, 1966 Elton, 1966 de Joannis, 1899 de Joannis, 1899 Moon, 1940 de Joannis, 1899; Forbes, 1923; Baer, 1924; Davis (cited by Lutz, 1948) Methods Rats ( Rattus norvegicus) were fed to five Great Horned Owls ( Bubo virginianus). Pellets and pellet fragments were collected as soon as possible after regurgitation. They were dried in an oven at 60 °C for 24 hours. Dry weight and volume were 104 RAPTOR RESEARCH Vol. 13 No. 4 measured. The dry pellets were placed in 6-mm mesh nylon bags and frozen. On 3 July 1973, 90 “pellet bags” were set out in a maple-oak stand at our College’s Forest Experiment Station, Lafayette Road, Syracuse, New York. The pellets varied in weight from 3.08 to 11.47 g (av. 6.06); length ranged from 33 to 86 mm (av. 49.71) and width, from 20 to 34 mm (av. 25.11). Six pellets were removed every 8 days for 4 months. Five pellets were placed in modified Tullgren funnels for extraction of invertebrates. As the pellets air-dried, des- iccation drove out the invertebrates, which fell into a collecting jar containing an al- cohol and glycerin solution placed at the base of the funnel. The remaining pellet was used for culturing of fungi and invertebrates. Portions of the pellet were in- cubated on moist filter paper in a petri dish in the dark at 25° C. When insects hatched, they were preserved in alcohol. As fungal growth became evident, pieces of the pellet were transferred onto mycobiotic agar. The other half of the pellet was used for culturing of fungi by means of the soil-dilution agar plate method (Menzies 1965). Dilutions from 1CM to HP 6 were used with preparations of mycobiotic and malt agars. Results and Discussion After 4 months’ exposure to field conditions, pellets weighed from 38.03 to 89.53 percent of their initial dry weight, averaging 62.87 percent (fig. 1). Decomposition rates were highly variable because of differences in size, composition, micro- environment, and faunal and floral colonization of pellets. Physical Factors. Weather is a major factor in pellet decomposition. Rain flattens the pellet, dissolves the mucus, washes hair away from bones near the surface of the pellet, and helps create entry holes for invertebrates. Freezing and thawing are also important (Wilson 1938). Faunal Microcommunity. Fresh moist pellets attract flies, such as Calliphoridae and Anthomyiidae, which deposit their eggs on the pellets. Such flies do not appear to be attracted to dried or older pellets. Other flies may be found on older, moist pellets; however, pellets may at times represent islands of moisture on the soil litter surface and attract cryptozoans, such as sowbugs and earthworms. Snails and slugs can also be found on pellets, and the large slug Limax maximus often leaves a trail of mucus on pellets it has visited nocturnally. Various transient species, such as ants, centi- pedes, millipedes, and spiders, also visit pellets, as well as occasional hungry mam- mals (Wilson 1938, Fleay 1968) and industrious pack rats (Griffin 1976, Long and Kerfoot 1963). Pellets support large populations of protozoa and nematodes, and even tardigrades may be present. Pellets serve as habitat for beetles such as Leptodiridae and Staphylinidae. Various parasitic wasps find pellets to be a source of hosts. Predatory, parasitic, fungivorous, and saprophagous mites all were found. Akimov and Shehur (1972) have shown that the acarid mites Tyrophagus putrescentiae (Schrank), Glycyphagus domesticus (Deg.), and Rhizoglyphus echinopus (Fum. et Rob.) cannot digest keratin but feed on the lip- ids associated with keratinous substances such as feathers. However, other possible food sources are present, on feathers and pellets. Also, we have often found larvae, nymphs, and adults of T. putrescentiae , on pellets, with alimentary tracts filled with hyphae and fungal spores. The two most important pellet invertebrate decomposers are the tineid moths and Winter 1979 Philips & Dindal— Raptor Pellets 105 the trogid beetles. The larvae of the Tineidae, or clothes moths (fig. 2), eat hair and feathers, and we have found over 60 of them in a single pellet. Pellets sometimes ap- pear to be covered ventrally with a centimeter or more of debris. Actually this is a thin layer of soil and moth excreta covering many cases of silk constructed by the larvae. These cases range from 7 to 18 mm long by 2 mm wide, and the larvae feed and pupate within them. The open end of the case is in the pellet and the case re- sembles a small “sock” sticking out of the pellet. In decomposed pellets, the silken network of these moth cases may be all that holds the remaining bones together. Fly larvae of the genus Scenopinus prey on tineid larvae in pellets (de Joannis 1899). The trogid beetles also feed on hair and feathers, and their larvae burrow into the soil beneath the pellet. The burrows may be 30 mm deep by 2 mm wide, and they may be lined with hair for the upper 20 mm. Trogid beetles also serve as transporta- tion for uropodine and macrochelid mites (Sixl 1971). Many mites attach themselves to insects for transportation from one site to another. This relationship is known as phoresy. A mesostigmatic mite Macrocheles penicilliger (B.) has been reported phoret- ic on Trox scaber in owl nests in England (fig. 3). We have found it on Trox variola- tus in pellets and rat carrion in central New York. In addition we have found nema- todes that are also phoretic on the phoretic Macrocheles mite (fig. 3). There are several other published records of this type of nematode phoresy (Dindal 1973b, Ramsay 1970). Funnel extraction data for both tineid moths and trogid beetles was found to be unreliable because their cases provide considerable protection against desiccation. The trogid beetles are often found beneath the pellets— adults in the litter, and larvae in the soil. Millipedes, sowbugs, and earthworms were also observed on pellets more frequently than the extraction data indicates (table 2). Perhaps the most surprising find was a specimen of Radfordia. This prostigmatic mite is a small mammal ectoparasite which feeds in the bases of hair follicles (Krantz 1971). The specimen was in good condition but was probably dead and accidentally fell into the collecting jar during extraction. However, another specimen was obtain- ed in an extraction of fresh Great Horned Owl pellets. These findings bring up the question of whether ectoparasites may occasionally survive in the environment of a raptor’s stomach long enough to be regurgitated alive in a pellet. Chmielewski (1970) studied the passage of astigmatic mites through the alimentary canal of mice, spar- rows, and hens. Survival rates of some species varied from 1-7 percent. Survivors in- cluded individuals of all stages although eggs and resting stages were more resistant. Other parasites may also occasionally be found in pellets. Bond (1940) reported Great Horned Owl pellets in Nevada containing chicken ticks, Avgas persicus (Oken); for example, one pellet contained a gopher skull and 42 ticks. Also, roundworms such as Porrocaecum and Ascaridia are sometimes egested with pellets (Cooper 1972). In ad- dition to vertebrate parasites, we have periodically found insect and acarine parasites of other invertebrates on pellets. Pellet Flora. Thirteen species of fungi were isolated from the pellets (table 3). Oth- er species of fungi were observed on the pellets, but culture attempts failed. The most important species (as judged by visible growth) are Trichoderma sp. and Chry- sosporium tropicum Carmichael. Large green patches of Trichoderma at times covered up to 20 percent of the pellet surface. Most pellets had some surface growth of Chry- sosporium, and some appeared extremely white as the fungus took over as much as 106 RAPTOR RESEARCH Vol. 13 No. 4 Table 2. Invertebrates from Great Horned Owl Pellets no. no. of max. no. pellets specimens on one (75) pellet Prostigmata 73 1,840 156 Collembola 55 884 84 Oribatei 63 369 57 Mesostigmata 53 241 42 Lepidoptera 43 194 22 Astigmata 18 27 6 Coleoptera 14 26 9 Hymenoptera 9 17 6 Gastropoda 9 13 2 Diptera 7 12 2 Isopoda 9 11 2 Homoptera 8 8 1 Araneida 7 8 2 Chilopoda 3 4 2 Thysanoptera 2 4 3 Psocoptera 3 3 1 Diplopoda 1 1 1 Oligochaeta 1 1 1 Pauropoda 1 1 1 Symphyla 1 1 1 Total 3,665 Av. no. /pellet 48.87 Mites 67.59% Av. no./g dry wt 9.25 Insects 31.32% Max. no./g dry wt Others 1.09% on one pellet 48.00 Table 3. Fungi from Great Horned Owl Pellets Alternaria sp. * Aspergillus flavus Link Aspergillus fumigatus Fresenius * Aspergillus niger Van Tieghem Aspergillus sp. Chaetomium sp. Chrysosporium tropicum Carmichael * Fusarium roseum section Paecilomyces sp. Rhizopus sp. S porotrichum sp. Trichoderma sp. * species not previously reported from pellets Winter 1979 Philips & Dindal— Raptor Pellets 107 75 percent of the surface (fig. 4). Chrysosporium is a keratinophilic fungus which at- tacks hair with the aid of penetrating bodies (Carmichael 1962). This genus is com- mon on bird feathers and in their nests (Pugh 1966, 1972; Pugh and Evans 1970; Ot- cenasek et al. 1967; Rees 1967; Hubalek 1974. While Aspergillus fumigatus, the cause of aspergillosis in birds, was found, its occurrence in pellets does not appear to be an unusual source of infection since the fungus is so widespread. Summary Pellets may serve as a site of breeding, feeding, and shelter for many invertebrates and as a substrate for growth of a variety of fungi. Some invertebrates consume vari- ous pellet components such as the lipids of hair and feathers while others feed on the fungi. Still other predatory or parasitoid invertebrates are attracted to pellets where they afflict some of the “pioneer” invertebrates. Pellets may be found in many habitats. They are produced by many avian and oth- er vertebrate species, and they differ widely in composition depending upon the prey species. For these reasons pellets are excellent instructional tools since they illustrate so many aspects of ecology. Much remains to be learned about pellets as habitats for microbe and invertebrate microcommunities. A cknow ledgments We thank Jack Gray for allowing us to use two of the owls of the Burnet Park Zoo, Syracuse, and Dr. A. A. Padhye of the Center for Disease Control, Atlanta, Georgia, for identifying the fungi. Also, Dr. Roy A. Norton graciously aided in the identification of the mite species we collected. Literature Cited Akimov, E. A., and L. E. Shehur. 1972. Features of the nutrition of the grain mites Glycyphagus domesticus (Deg.) and Tyrophagus putrescentiae (Schr.) and the root mite Rhizoglyphus echinopus (Fum. et Rob.) on some proteinoids. (In Rus- sian, English summary). Vestnik Zoo/. 6(6): 45-48. Aubrook, E. W. 1939. Insects bred from owl pellets. Entomol. Mon. Mag. 75:88. Baer, W. 1924. Biologische Beobachtungen an Kleidermotten. Naturw. Korresp. 2:122-123. Bond, R. M. 1940. Food habits of horned owls in the Pahranagat Valley, Nevada. Condor 42(3): 164-165. Brooks, A. 1929. On pellets of hawks and owls. Condor 31:222-223. Buxton, P. A. 1914. Habit of Tinea rusticella. Entomol. Rec. 26:143. Carmichael, J. W. 1962. Chrysosporium and some other aleuriosporic hyphomycetes. Canadian J. Bot. 40:1137-1174. Chmielewski, W. 1970. The passage of mites through the alimentary canal of verte- brates. Ekol. Pol. Ser. A. 18(35):741-756. Cooper, J. E. 1972. Hawks and parasites. Hawk Chalk 11:31-35. Davis, T. A. W. 1975. Food of the kestrel in winter and early spring. Bird Study 22(2):85-91. Davis, W. T. 1909. Owl pellets and insects. /. New York Entomol. Soc. 17(2):49-51. Dillon, E. S., and L. S. Dillon. 1961. A manual of common beetles of Eastern North America. Dover Publications, New York. 2 vols. 894 pp. 108 RAPTOR RESEARCH Vol. 13 No. 4 Dindal, D. L. 1973a. Microcommunities defined. Pages 2-6 in D. L. Dindal (ed.), Soil Microcommunities I, Proc. First Conf. Nat. Tech. Information Serv. USAEC. CONF-711076, Springfield, Virginia. Dindal, D. L. 1973b. Review of symbiotic relationships in soil invertebrates. Pages 227-256 in D. L. Dindal (ed.), Soil Microcommunities I., Proc. First Conf. Nat. Tech. Information Serv. USAEC. CONF-711076, Springfield, Virginia. Dobrokhotov, B. P., and V. Yu. Litvin. 1971. Radioactivity of pellets of Falco tinnun- culus L. after feeding on mice containing P 32 . (In Russian, English summary). Zool.Zh. 50:1591-1592. Dobroruka, L. J. 1973. Pellet formation in the Japanese giant salamander. Int. Zoo. Yrbk. 13:158. Duke, G. E., J. C. Ciganek, and O. A. Evanson. 1973. Food consumption and energy, water and nitrogen budgets in captive Great Horned Owls ( Bubo virginianus). Comp. Biochem. Physiol. 44(A):283-292. Duke, G. E., O. A. Evanson, and A. Jegers. 1976, Meal to pellet intervals in 14 spe- cies of captive raptors. Comp. Biochem. Physiol. 53(A): 1-6. Duke, G. E., A. A. Jegers, G. Loff, and O. A. Evanson. 1975. Gastric digestion in some raptors. Comp. Biochem. Physiol. 50(A) :649-656. Elton, C. S. 1966. The pattern of animal communities. Wiley, New York. 432 pp. Fleay, D. 1968. Nightwatchmen of bush and plain. Taplinger, New York. 163 pp. Forbes, W. T. M. 1923. The Lepidoptera of New York and neighboring states. Primi- tive forms, Microlepidoptera, Pyraloids, Bombyces. Mem. Cornell Agric. Exp. Sta. No. 68. 729 pp. Glue, D. E. 1973. Owl pellets. Pages 193-197 in J. A. Burton (ed.), Owls of the world. E. P. Dutton, New York. Griffin, C. R. 1976. A preliminary comparison of Texas and Arizona Harris’ Hawks (. Parabuteo unicinctus) populations. Raptor Res. 10(2):50-54. Hinton, H. E. 1956. The larvae of the species of Tineidae of economic importance. Bull. Entomol. Res. 47:251-346. Hubalek, Z. 1974. The distribution patterns of fungi in free-living birds. Acta Sc. Nat. Brno 8(9): 1-51. Jellison, W. L. 1939. Sylvatic plague: Studies of predatory and scavenger birds in re- lation to its epidemiology. U.S. Public Health Service. Public Health Reports 54:792-798. Joannis, J. de. 1899. Note sur quelques Microlepidopteres dont les chenilles se nour- issent de poils d’animaux. Bull. Soc. Entomol. Fr. 1899:248-250. Krantz, G. W. 1971. A manual of acarology. Oregon State Univ. Book Stores, Inc., Corvallis, Oregon. 335 pp. Lobachev, V. S., M. E. Levi, and M. M. Levschitz. 1971. The preservation of a spe- cific antigen of a plague-causing agent in the food pellets of predatory birds. (In Russian, English summary). Zool. Zh. 50:1593-1595. Lobachev, V. S., and G. Shenbrot. 1974. Food of the Little Owl in the North Aral Sea area. (In Russian). Ornitologiya 11:382-390. Long, C. A., and W. C. Kerfoot. 1963. Mammalian remains from owl-pellets in east- ern Wyoming. J. Mammal. 44(1): 129-131. Lutz, F. E. 1948. Field book of insects. G. P. Putnam’s Sons, New York. 510 pp. Marti, C. D. 1974. Feeding ecology of four sympatric owls. Condor 76(1):45-61. Winter 1979 Philips and Dindal— Raptor Pellets 109 Meinertzhagen, R. 1959. Pirates and predators. Oliver and Boyd, London. 230 pp. Menzies, J. D. 1965. Fungi. Pages 1502-1505 in C. A. Black (ed.), Methods of soil analysis. Part 2. Am. Soc. Agronomy Inc., Madison, Wisconsin. Moon, E. L. 1940. Notes on hawk and owl pellet formation and identification. Trans. Kansas Acad. Sci. 43:457-466. Morton, S. R., M. Happold, A. K. Lee, and R. E. MacMillan. 1977. The diet of the bam owl, Tyto alba, in southwestern Queensland. Australian Wildl. Res. 4:91-97. Nurse, C. G. 1906. Food of Monopis rusticella. Entomologist 39:160. Otcenasek, M., K. Hudec, Z. Hubalek, and J. Dvorak. 1967. Keratinophilic fungi from the nests of birds in Czechoslovakia. Sabouradia 5:350-354. Peterson, A. 1960. Larvae of insects. Part 2. Edwards Bros., Ann Arbor, Michigan. 416 pp. Prestt, I., and R. Wagstaffe. 1973. Barn and bay owls. Pages 42-60 in J. A. Burton, (ed.), Owls of the world. E. P. Dutton, New York. Pugh, G. J. F. 1966. Associations between birds’ nests, their pH, and keratinophilic fungi. Sabouradia 5:49-53. 1972. The contamination of birds’ feathers by fungi. Ibis 114:172-177. Pugh, G. J. F., and M. D. Evans. 1970. Keratinophilic fungi associated with birds. I. Fungi isolated from feathers, nests, and soils. Trans. British Mycol. Soc. 54(2):233-240. Ramsay, G. W. 1970. Mites with phoretic nematodes. New Zealand Entomol. 4(4):91-92. Rees, R. G. 1967. Keratinophilic fungi from Queensland. II. Isolation from feathers of wild birds. Sabouradia 6:14-18. Simmons, G. E. 1971. Patterns of life in woodland communities. 8. Bird pellets. Quar- terly J. Forestry. 65:224-231. 1973. The study of bird pellets. Country Side 22:116-122. Sixl, W. 1971. Ein Beitrag zur Kenntnis der Phoresie. Mitt, naturwiss. Ver. Steier- mark. 100:405-406. Smith, C. R., and M. E. Richmond. 1972. Factors influencing pellet egestion and gas- tric pH in the Barn Owl. Wilson Bull. 84:179-186. Tucker, B. W. 1944. The ejection of pellets by passerine and other birds. British Birds 38:50-52. Vaurie, P. 1955. A revision of the genus Trox in North America (Coleoptera, Scara- baeidae). Bull. American Mus. Nat. Hist. 106(1): 1-89. Vernon, C. J. 1972. An analysis of owl pellets collected in southern Africa. Ostrich 43:109-124. Wallace, G. J. 1948. The Barn Owl in Michigan. Its distribution, natural history and food habits. Michigan State Coll. Agric. Exp. Sta. Tech. Bull. 208. 61 pp. Watling, R. 1962. Fungal succession on kestrel pellets. Naturalist 41-43. Watling, R. 1963. The fungal succession on hawk pellets. Trans. British Mycol. Soc. 46(l):81-90. Wilson, K. A. 1938. Owl studies at Ann Arbor, Michigan. Auk 55:187-197. 110 RAPTOR RESEARCH Vol. 13 No. 4 DECOMPOSITION RATES of GREAT HORNED OWL PELLETS MONTH Figure 1. Decomposition rate of Great Homed Owl pellets. Figure 2. Larva of clothes moth, Tineidae (head capsule indicated by arrow). Winter 1979 Philips and Dindal— Raptor Pellets 111 Figure 4. Growth of the white keratinophilic fungus, Chrysosporium tropicum, on surface of decomposing Great Horned Owl pellet. OBSERVATIONS ON THE BEHAVIOR OF WINTERING BALD EAGLES by Howard I. Russock Department of Biological and Environmental Sciences Western Connecticut State College Danbury, Connecticut 06810 Abstract The behavior of four Bald Eagle ( Haliaeetus leucocephalus ) was studied in western Connecticut during the winter of 1976-77. The eagles congregated below a hydro- electric dam which killed and injured large numbers of fish. The Bald Eagles ate these fish almost exclusively when in the vicinity of the dam and were never observed to hunt the waterfowl which also congregated in the area. Crows were observed to mob or har- ass the eagles on ten occasions. The eagles exhibited soaring behavior on seventeen oc- casions. Soaring has been considered an aspect of play and courtship; evidence is pre- sented which suggests that soaring may also be involved in agonistic interactions. Introduction The behavior of the Bald Eagle ( Haliaeetus leucocephalus ) has been studied many times. Most of these investigations have concentrated on reproductive and nesting be- havior. Comparatively few studies have dealt with migratory Bald Eagles on their win- tering grounds (Southern 1963, 1964; Hancock 1964; Ingram 1965; Lish 1973; Platt 1976), and fewer still have concentrated on the behavior of wintering eagles. This paper is a report of one winter of observations on the behavior of Bald Eagles in western Connecticut. The eagles congregated below the Shepaug Hydroelectric Dam on the Housatonic River; the dam’s generators kept the otherwise frozen river open and killed or injured large numbers of fish. The National Audubon Society Continental Bald Eagle Project has reports of Bald Eagles wintering in the Shepaug Dam area as early as December 1963, with the possible existence of an active nest in the area until 1966. Local residents have reported observ- ing wintering Bald Eagles in the area as early as 1953; there are also reports of Bald Eagles wintering along the Connecticut River near Essex. Study Area and Methods The Bald Eagles were observed in the vicinity of the Shepaug Hydroelectric Dam on the Housatonic River, approximately 4.6 km north of Newtown, Connecticut. Most ob- servations were made on the property of the Connecticut Light and Power Company, located on the north shore of the river and extending for 0.8 km east (downstream) of the dam; additional observations were made on a public road which follows the north side of the river for an additional 3.4 km. Above the dam is a lake surrounded by un- developed woodland. The subjects were observed with field binoculars (7x35) and a telescope (80-160X); observations were dictated into a tape recorder. This report covers more than 50 hr of observation. 112 Raptor Research 13(4): 112- 115 Winter 1979 Russock— Behavior of Bald Eagles 113 Results and Discussion Four Bald Eagles (one adult, three immatures) were observed. According to the plu- mage classifications of Bent (1937) and Southern (1964), the immature eagles were ap- proximately 2-3 (A), 3-4 (B), and 4 years old (C). The first observation of each eagle was between 14 December 1976 and 3 January 1977. The eagles were observed for the last time between 23 February 1977 and 11 March 1977. The river was frozen from 29 December 1976 to 24 February 1977, except for an area immediately below the dam when the dam’s generators were operating. The lake above the dam was frozen from before the eagles’ arrival until after they left. The departure of the eagles coincided with a period of consistently above-freezing temperatures which opened the river. The eagles normally arrived at the dam from the direction of the woodland above the dam and flew in the direction of the woodland upon leaving the feeding area. Presum- ably their roosting site(s) were located in this area. Several attempts to locate these sites were, however, unsuccessful. Feeding. With one exception, fish were the only observed prey of the eagles. Fish are the preferred food of Bald Eagles (Broley 1947, Southern 1966, Mc’Clelland 1973, Dun- stan and Harper 1975, Ofelt 1975), and wintering eagles have been reported to congre- gate near dams in many parts of the country (Sprunt 1961, Southern 1963, Ingram 1965, Spencer 1976). The eagles were observed to make swooping dives to the river to catch fish on 69 occasions, 33 of which were successful (47.8%). However, the two older birds (the adult and immature C) were successful 62.5% (20/32) of the time, while the two younger birds were successful only 35.1% (13/37) of the time (p< 0.025, Chi-Square Test). The species of fish they were catching was not determined; dead fish washed onto shore in- cluded White Perch (. Roccus americana ), Trout ( Salvelinus spp.), and Bass (Micropterus spp.). Interspecific Interactions . The large number of fish killed or injured by the dam’s gen- erators attracted many other birds to the area. Hundreds of Common Crow ( Corvus bra- chyrhynchos ) were present on all observation days as was a mixed-species flock of 50-200 Herring, Great Black-backed, and Ring-billed Gull ( Larus argentatus, L. ma- rinus, L. delawarensis). In addition, small numbers of the Canada Goose (Branta cana- densis ), the Mallard (Anas platyrhynchos ), the Common Merganser ( Mergus merganser), and the Great Blue Heron (Ardea herodias ) were often present. The eagles were never observed hunting the waterfowl, and an eagle was observed scavenging on waterfowl (a gull) on only one occasion. The apparent lack of interest of the eagles in the waterfowl is surprising because, next to fish, waterfowl are the preferred food of Bald Eagles and are often their primary food during the winter (Oberholser 1906, Brooks 1922, Bent 1937, Murrie 1940, Retfalvi 1970). However, Spencer (1976) has reported that Bald Eagles ignore waterfowl when fish are available, and Munro (1938) and Southern (1964) have reported cases of waterfowl ignoring Bald Eagles which were feeding nearby. Crows were observed harassing Bald Eagles on eight occasions and mobbing an eagle on two occasions. Harassment and mobbing were differentiated on the basis of length of the interaction and the number of crows involved. The eight interactions_classified as harrassments involved one to six crows (X = 3.0 =1= 1.6s) and lasted 1-5 min (X = 2.6 ± 1.4s min). Five harassments involved a perched eagle, and three occurred when an eagle was in the air; in two cases the eagle had a fish which the crows were apparently trying to 114 RAPTOR RESEARCH Vol. 13 No. 4 take. All harassments were directed against the immature eagles. Crows were never ob- served harassing or mobbing the adult eagle. Several studies have reported crows nesting or feeding near Bald Eagles (Baily 1927, Howell 1937, Southern 1964, Ingram 1965, Erskine 1968, Spencer 1976), and several others have reported crows harassing Bald Eagles or attempting to get their food (Her- rick 1932, Hausman 1948, Musselman 1949, Retfalvi 1970, Weekes 1975). Both instances of mobbing involved one immature eagle (C). The first case occurred on the first day the bird was observed and quite possibly the first time it had entered the study area. It took place while the bird was perched in a tree, lasted 10 min, and in- volved 100-110 crows. The other observed mobbing occurred two days later while the eagle was circling the study area; it lasted 13 min and involved 26 crows. Intraspecific Interactions. Only one unequivocal agonistic interaction was observed during more than 50 hr of observation. On that occasion an immature eagle (B) was perched on a branch eating a fish when a second immature eagle (C) landed on the same branch and made a pecking movement toward the first bird without making contact. The first bird immediately left the branch, and the second eagle grabbed the fish with its talons and began eating it. The only other observed intraspecific interactions involved soaring. During soaring two or more eagles swoop down upon each other, often perform rolls in the air in uni- son, turn over in the air and extend their talons up at the diving eagle, and sometimes try to take sticks from each other in midflight (Bent 1937, Platt 1976). Soaring has been observed as part of play behavior in immature eagles (Bent 1937, Platt 1976), during courtship and early nesting (Herrick 1924, Ingram 1965, Grewe 1966, Brown and Ama- don 1968), to signal the presence of a local food source (Sherrod et al. 1976), and during territorial defense (Mattsson 1974, Ogden 1975). Seventeen separate instances of soaring behavior were observed. Fifteen soaring bouts involved two eagles, and two involved all three immature eagles; the adult eagle was involved in only three of the seventeen bouts. The fourteen soaring bouts involving im- mature eagles could almost certainly be classified as play. In all cases the eagles took turns chasing each other, and both eagles remained in the feeding area after the bout; five of the fourteen bouts included transferring sticks in midair. However, it is possible that the three soaring bouts involving the adult were agonistic interactions. In all three cases the adult was alone when an immature eagle entered the dam area, and the adult flew up to meet it. In all three cases the adult chased the immature eagle, but the imma- ture eagle never chased or swooped down upon the adult. All three bouts ended with the immature eagle leaving the area. The adult and immature eagles coexisted in the feeding area on many other occasions. Acknowledgments I thank the Connecticut Light and Power Company for allowing me access to their property. I also thank Alexander Sprunt IV for providing the National Audubon Society Connecticut Bald Eagle File and John and M. Stoessel Wahl for the use of their Questar telescope. The following people provided me with personal information concerning the present and past history of Bald Eagles in Connecticut: Mrs. Polly Brody, Mr. Donald Hopkins, Mr. Fred King, and Mrs. John Stratton. Literature Cited Bailey, A. M. 1927. Notes on the birds of southeastern Alaska. Auk 44:1-23, 184-205. Winter 1979 Russock— Behavior of Bald Eagles 115 Bent, A. C. 1937. Life histories of North American birds of prey, part I. U.S. Nat. Mus. Bull 167:321-349. Broley, C. L. 1947. Migration and nesting of Florida Bald Eagles. Wilson Bull. 59:3-20. Brooks, A. C. 1922. Notes on the abundance and habits of the Bald Eagle in British Co- lumbia. Auk 39:356-359. Brown, L., and D. Amadon. 1968. Eagles, hawks, and falcons of the world, vol. 1. Ham- lyn Publ. Group, Middlesex. Dunstan, T., and J. Harper. 1975. Food habits of the Bald Eagle in north central Min- nesota. J. Wildl. Manage. 39:140-143. Erskine, A. J. 1968. Encounters between Bald Eagles and other birds in winter. Auk 85:681-683. Grewe, A. H. 1966. Some aspects in the natural history of the Bald Eagle, Haliaeetus leucocephalus, in Minnesota and South Dakota. Ph.D. dissertation, University of South Dakota (Abstract). Hancock, D. 1964. Bald Eagles wintering in the Southern Gulf Islands, British Colum- bia. Wilson Bull. 76:111-120. Hausman, L. A. 1948. Birds of prey. Rutgers Univ. Press, New Brunswick, NJ. Herrick, F. H. 1924. Nests and nesting habits of the American eagle. Auk 41:213-231. 1932. Daily life of the American eagle: Early phase. Auk 49:307-323, 428-435. Howell, J. C. 1937. The nesting Bald Eagles of southeastern Florida. Auk 54:296-299. Ingram, T. 1965. Wintering Bald Eagles at Guttenberg, Iowa-Cassville, Wisconsin, 1964-1965. Iowa Bird Life. 35:66-78. Lish, J. W. 1973. Bald Eagles wintering on the Leosho River, Oklahoma. Bull. Okla- homa Ornithol. Soc. 6:25-30. Mattsson, J. P. 1974. Interactions of a breeding pair of Bald Eagles with sub-adults at Sucker Lake, Michigan. Ph.D. dissertation, St. Cloud State University, St. Cloud, MN (Summary). Mc’Clelland, B. R. 1973. Autumn concentration of Bald Eagles in Glacier National Park. Condor 75:121-123. Munro, J. A. 1938. The northern Bald Eagle in British Columbia. Wilson Bull. 50:28-35. Murrie, O. 1940. Food habits of the northern Bald Eagle in the Aleutian Islands, Alaska. Condor 42:198-202. Mussleman, T. E. 1949. Concentrations of Bald Eagles on the Mississippi River at Ham- ilton, Illinois. Auk 66:83. Oberholser, H. C. 1906. The North American eagles and their economic relations. U.S. Bureau Biol Ser. Bull. 27:1-31. Ofelt, C. H. 1975. Food habits of nesting Bald Eagles in southeast Alaska. Condor 77:337-338. Ogden, J. 1975. Effects of Bald Eagle territoriality on nesting Ospreys. Wilson Bull. 87:496-505. Platt, J. B. 1976. Bald Eagles wintering in a Utah desert. American Birds 30:783-788. Retfalvi, L. 1970. Food of nesting Bald Eagles on San Juan Island, Washington. Condor 72:358-361. Sherrod, S. K., C. M. White, and F. S. L. Williamson. 1976. Biology of the Bald Eagle on Amchitka Island, Alaska. Living Bird, 15th Annual, pp. 143-182. Southern, W. E. 1963. Winter populations, behavior, and seasonal dispersion of Bald Eagles in northwestern Illinois. Wilson Bull. 75:42-55. 1964. Additional observations on winter Bald Eagle populations: Including re- marks on biotelemetry techniques and immature plumages. Wilson Bull. 76:121-137. 1966. Utilization of shad as winter food by birds. Auk 83:309-311. Spencer, D. A. 1976. Wintering of the migrant Bald Eagle in the lower 48 states. Na- tional Agricultural Chemicals Association, Washington, D.C. Sprunt, A. 1961. An eagle-eyed look at our Bald Eagle. Audubon Mag. 63:324-327. Weekes, F. 1975. Behavior of a young Bald Eagle at a southern Ontario nest. Canada Field-Nat. 89:35-40. USE OF HUNTING METHODS BY FERRUGINOUS HAWKS IN RELATION TO VEGETATION DENSITY by James S. Wakeley School of Forest Resources The Pennsylvania State University University Park, PA 16802 Abstract To test the hypothesis that hawks increase their foraging efficiency by selecting the most appropriate hunting technique for a particular habitat type, I studied the rela- tive use of 4 hunting methods by 2 Ferruginous Hawks in relation to the density of vegetative cover. No trends in relative use of hunting methods with increasing vege- tation density could be detected, indicating either that efficiency of hunting methods did not change with increasing cover density or that factors other than cover density were more important in the hawks’ choice of hunting methods for a particular site. Introduction There is increasing interest in foraging behavior of hawks, especially in factors af- fecting the selection of habitats for hunting and efficiency of food gathering in vari- ous vegetation types. Besides answering important behavioral questions, such informa- tion has potential management importance in areas of changing land use. That hawks use more than one hunting technique, which may differ in energy ex- penditure and in rate of return, complicates such studies. An individual bird’s choice of hunting methods may depend upon its relative efficiency in terms of prey cap- tured per unit of energy expended (Wakeley 1978b). Furthermore, the hunting meth- od which is most efficient in one vegetation type within a bird’s home range may be inferior to another method in a different vegetation type. Thus a hawk might in- crease its overall foraging efficiency by selecting the most appropriate technique for a particular habitat. This study examines trends in the relative use df 4 hunting methods by 2 Ferru- ginous Hawk ( Buteo regalis) in relation to increasing density of vegetative cover, and evaluates the effect of such trends, if any, on foraging efficiency. Wakeley (1978a) determined that cover density was the most important factor influencing the use of 116 Raptor Research 13(4): 116 Winter 1979 Wakeley— Hunting of Hawks 117 hunting sites by these Ferruginous Hawks, so it seems logical to examine the hawks’ use of hunting methods relative to this parameter. Herein I make no attempt to extrapolate my results on only 2 hawks to the popu- lation as a whole. However, a consequence of learning by individuals must ultimately be reflected in the average response of a population. Methods The study area in southern Idaho and the methods used were described elsewhere (Wakeley 1978a, b). Briefly, the study area consisted of the home ranges of 2 adult male Ferruginous Hawks and was a mosaic of vegetation types including agricultural crops (alfalfa, grains), small pastures, old fields, open shrubland, and bare areas. I measured the density of vegetative cover by a point-quadrat technique and cate- gorized all vegetation into 1 of 4 cover-density classes: absent (< 5% vegetative cov- erage), sparse (5-20% coverage), moderate (20-75% coverage), and dense (>75% cov- erage). To determine the use of cover-density classes for foraging, I observed strikes made by the 2 adult male hawks; male 1 was watched in 1974 and male 2, in 1975. Obser- vations were made from a blind during the nestling period. The hawks hunted (1) from the ground, (2) from a perch, (3) from low-altitude (active) flight, and (4) from high-altitude (soaring) flight. All observed strikes were categorized by the hunting method used. I used a graphical technique to look for trends in use of hunting meth- ods with increasing vegetation density (fig. 1). Neither hawk was marked; yet with experience, I had no trouble identifying the birds at a distance and distinguishing them from other hawks in the area. Identification was confirmed when the birds re- turned to their nests. Results I witnessed 430 strikes in 1974 and 378 strikes in 1975. Table 1 shows the distribu- tion of these strikes among hunting methods and cover-density classes. In each year, chi-square tests indicated that there were significant differences in relative use of hunting methods in areas of different vegetation density (P< .01). Table 1. Number of Strikes by Ferruginous Hawks in Relation to Hunting Method and Vegetation Density. Cover density Hunting Method Ground Perch Low flight High flight Total Absent 61( 7) 154( 42) 70( 47) 16( 62) 301(158) Sparse 9( 3) 7( 7) 33( 10) 16( 1) 65( 21) Moderate ?( 0) 17( 1) 6( 8) 17( 0) 47( 9) Dense 4( 4) 0( 56) 11( 43) 2( 87) 17(190) Totals 81(14) 178(106) 120(108) 51(150) 430(378) “Male 1 (1974) without parentheses; Male 2 (1975) within parentheses. 118 RAPTOR RESEARCH Vol. 13 No. 4 The number of strikes by a hunting method in each cover-density class was ex- pressed as a percentage of total strikes within that class. Despite the significant dif- ferences in use of hunting methods within areas of different vegetation density, no consistent trends in use of hunting methods with increasing cover density could be detected (fig. 1). Discussion I expected to find that the hawks hunted from the ground or from a perch more often in areas of absent or sparse cover than in moderate or dense cover. A hawk’s low viewing angle, especially from the typical fencepost perch, would seemingly ex- aggerate the prey-concealing effect of any vegetation present, making that technique less efficient in moderately or densely vegetated areas. However, this hypothesis was not supported by the results. The results were apparently not influenced by the relative availability of hunting perches near each habitat type. Hunting perches (wooden fenceposts, telephone poles, juniper trees) were present throughout the study area within or adjacent to all vege- tation types. The availability of perches was not quantified, but their number and placement seemed more than adequate to meet the hawks’ requirements. Earlier (Wakeley 1978b), I showed that both hawks increased their overall foraging efficiency by emphasizing their more efficient hunting technique (sit-and-wait hunting from a perch or from the ground). Hawks apparently did not adjust their efficiency further by matching the best hunting method to a particular type of cover, perhaps because there was no difference in relative efficiency of the 4 methods as cover den- sity increased. Another possibility is that some factor other than vegetation density was more important in the hawks’ choice of hunting methods for a particular area. Unfortunately, my data are not sufficient to resolve this question. A cknow lodgments This study was supported in part by the Chapman Fund of the American Museum of Natural History and by the Society of Sigma Xi. W. M. Tzilkowski provided statis- tical advice. Literature Cited Wakeley, J. S. 1978a. Factors affecting the use of hunting sites by Ferruginous Hawks. Condor 80:316-326. Wakeley, J. S. 1978b. Hunting methods and factors affecting their use by Ferruginous Hawks. Condor 80:327-333. PERCENTAGE OF STRIKES Winter 1979 Wakeley— Hunting of Hawks 119 Figure 1. Relationship between density of vegetative cover and relative use of hunting methods by Ferru- ginous Hawks. Vegetation density is plotted at the midpoint of the cover-density class for absent (A), sparse (S), moderate (M), and dense (D) vegetation. COOPER’S HAWK ATTACKS SHARP-TAILED GROUSE by D. L. J. Moyles 1 10315 - 79 St. Edmonton, Alberta T6A 3G7 CANADA On 21 April 1976, while observing the morning display of male Sharp-tailed Grouse ( Pedioecetes phasianellus ) on an arena 13 km (8 mi) west of Wainwright, Al- berta (lat. 52°49'; long. 110°59'), P. Harris saw a female Cooper’s Hawk (Accipiter cooperii ) attack an adult male sharptail. This attck came approximately one— half hour after sunrise; the hawk flew close to the ground from bushes 30 m from the arena and knocked the grouse off its feet. After a brief struggle in which the grouse lost some breast feathers, it escaped and flew off. The hawk did not pursue but in- stead flew onto a post. After 2 minutes it flew off. Although Beebe (1974) reported that Cooper’s Hawks do occasionally kill large birds, such as Ring-necked Pheasants ( Phasianus colchicus) and Mallards (Anas platy- rhynchos), it has not been reported to attack Sharp-tailed Grouse. Neither Artmann (1970) nor Brown (1970) saw Cooper’s Hawks attempting to kill these grouse. How- ever, Berger et al. (1963) reported one possible case of an adult male Greater Prairie Chicken ( Tympanuchus cupido pinnatus ) having been killed by a Cooper’s Hawk. Both these species of grouse display on open ground and have been observed to crouch, then flush upon the approach of a Cooper’s Hawk (Berger et al. 1963; pers. obs.). This may be a result of the grouse’s mistaking the shape and flight pattern of a Cooper’s Hawk for that of a Goshawk ( Accipiter gentilis) or because the incidence of attacks on grouse by Cooper’s Hawks is sufficiently frequent that they are recognized as potential predators themselves. I would like to acknowledge financial support from Department of Parks, Recrea- tion and Wildlife, Province of Alberta, and from a National Research Council of Canada grant (2010) to D. A. Boag. R. Fyfe of Canadian Wildlife Service allowed me to use the CWS facilities at Wainwright. D. A. Boag made helpful suggestions on this note. Literature Cited Artmann, J. W. 1970. Spring and summer ecology of the Sharptail Grouse. Ph.D. dis- sertation, Univ. of Minnesota. Xerox University Microfilms, Ann Arbor, Mich- igan. Beebe, F. 1974. Field studies of the Falconiformes of British Columbia. British Co- lumbia Provincial Museum. Occasinal Paper Series No. 17. Berger, D. D,, F. Hamerstrom, and F, N. Hamerstrom, Jr. 1963. The effect of raptors on Prairie Chickens on booming grounds. /. Wildl. Manage. 27:778-791. Brown, R. J. 1970. Organization and function of the spring and autumn lek of the Sharptailed Grouse ( Pedioecetes phasianellus jamesi). M.Sc. thesis, Univ. of Manitoba, Winnipeg. 1. Present address: Brooks Wildlife Center, Box 1540, Brooks, Alberta, CANADA TOJ OJO 120 Raptor Research 13(4): 120 SUBTERRANEAN NESTING BY PRAIRIE FALCONS b y Bruce A. Haak and S. Jon Denton Department of Fisheries and Wildlife Oregon State University Corvallis, Oregon 97331 Unusual nest site selection in Prairie Falcons ( Falco mexicanus) has rarely been re- corded. Variations from typical nest sites include one instance of tree nesting (Goss 1891) and one attempt within a hole in a lava fault (Pitcher 1977). On 18 May 1974, we discovered a successful subterranean Prairie Falcon nest site at Rattlesnake Cave in Malheur County, Oregon. This cave, a sink-hole approximately 24 m in diameter, was formed by the collapsed roof of a lava tube. Surrounding terrain was slightly rolling with no significant relief. The nest was placed 3 m below the ground on a 12-m-high vertical wall at the mouth of the cavern. At the time of discovery the nest contained two downy young which were observed as fledglings on 20 June 1974. To our knowledge this observation constitutes the first re- port of successful subterranean nesting by Prairie Falcons. An additional subterranean Prairie Falcon nest site was reported to us (Robert Beasley, Stewart Janes, and Caryn Talbot, pers. comm.). This site, located in Lake Coun- ty, Oregon consisted of a fissure approximately 804 m long, 1.5 m wide, and 4.5 m deep in an area characterized by otherwise flat terrain. The nest ledge was 1.2 m below ground level. Young fledged from this site in 1972 and 1976. At both locations, the nesting platform consisted of stick nests probably abandoned by Common Ravens ( Corvus corax ) or Red- tailed Hawks ( Buteo jamaicensis ). The use of stick nests by Prairie Falcons and their somewhat sympatric relationship with Common Ravens was documented (Decker and Bowles 1930, Skinner 1938). Of the hawks and falcons in western grasslands, Prairie Falcons were shown to be the least versatile in their nest-site selection (Olendorff and Stoddart 1974). However, the occupancy of abandoned quarries by Prairie Falcons (Smith and Murphy 1973) and the reports herein indicate a certain level of adaptability of this species by their willingness to occupy atypical nest sites. We thank R. Beasley, S. Janes, and C. Talbot for supplying data, and J. A. Crawford and R. T. Reynolds for reviewing the text. Literature Cited Decker, F. R., and J. H. Bowles. 1930. The Prairie Falcon in the state of Washington. Auk 47:25-31. Goss, N. S. 1891. History of the birds of Kansas. Geo. W. Crane & Co., Topeka, Kansas. Olendorff, R. R., and J. W. Stoddart, Jr. 1974. The potential for management of raptor populations in western grasslands. Pages 47-88 in F. N. Hammerstrom, Jr., B. E. Harrel, and R. R. Olendorff (eds.), Management of raptors. Raptor Res. Report No. 2, pp. 44-88. Pitcher, E. J. 1977. Nest site selection for Prairie Falcons. Auk 94(2) :371. 121 Raptor Research 13(4):117-118 122 RAPTOR RESEARCH Vol. 13 No. 4 Skinner, M. P, 1938. Prairie Falcon. Pages 18-42 in A. C. Bent (ed.), Life histories of North American birds of preu. Part 2. Smithsonian Inst., U.S. Natl. Mus. Bull. 170. 482 pp. Smith, D. G., and J. R. Murphy. 1973. Breeding ecology of raptors in the eastern Great Basin of Utah. Brigham Young Univ. Sci. Bull., Biol. Ser. 18(3): 1-76. Figure 1. Prairie Falcon nest site at cave entrance. Arrow shows location of stick nest platform. RED-TAILED HAWK PREYS ON ADULT SAGE GROUSE IN NORTHERN UTAH by Cal McCluskey Rureau of Land Management 2370 South 2300 West Salt Lake City, Utah 84119 Numerous authors have documented that the Red-tailed Hawk (Buteo jamaicensis ) feeds predominantly, but not entirely, on mammals. Fitch et al. (1946) noted in Cali- fornia that the redtails diet reflected the relative abundance of prey species, such as ground squirrels, and changed to alternate species as squirrel abundance declined. Luttich et al. (1970) noted that mammals constituted 60 percent of redtail diets in their Alberta study area, and birds averaged 31 percent. Of bird remains found at ac- tive nests, 4 percent were forest grouse. Craighead and Craighead (1956) found that Sage Grouse occurred in only 1.6 percent of redtail diets in their Wyoming study area. They noted that in general, redtail’s prefer to prey on small mammals but do occasionally prey on small birds. Wallestad (1976) noted that Montana redtails pose a threat to young Sage Grouse but not to adults. I saw an adult female Red-tailed Hawk attack a female Sage Grouse near Six Mile Creek, Rich County, Utah, on 27 September 1978. The Sage Grouse was feeding in a moist meadow with approximately 35 others when I saw the approaching hawk. The group became visibly restless as the hawk approached within 100 m. When the red- tail had come within 50 m, a few birds began flushing. Almost immediately, the red- tail stooped and struck a single grouse. The grouse was struck approximately 2 me- ters above ground level, at the base of the back. The grouse and hawk remained together until they hit the ground. The hawk remained on top of the grouse until flushed by my approach. Examination of the grouse revealed that no bones were bro- ken; however, the bird was unable to fly and appeared partially paralyzed. The wound consisted of several small punctures at the base of the back along both sides of the pelvis. The grouse was an adult female, weighing approximately 1500 g. Craig- head and Craighead (1965) reported that adult female redtails averaged 1224 grams, approximately 269 grams (18 percent) less than the average female Sage Grouse. They also noted that, in general, only extremely aggressive redtails will attempt to kill an animal larger than themselves. Literature Cited Craighead, J. J., and F. C. Craighead. 1956. Hawks, owls, and wildlife. Stackpole, Harrison, Pa. 443 p. Fitch, H. F., F. Swenson, and D. F. Tillotson. 1946. Behavior and food habits of the Red-tailed Hawk. Condor 48:205-237. Luttich, S., D. H. Rusch, E. C. Meslow, and L. B. Keith. 1970. Ecology of Red-tailed Hawk predation in Alberta. Ecology 51(2): 190-202. Wallestad, R. 1975. Life history and habitat requirements of Sage Grouse in central Montana. Montana Dept, of Fish and Game. 66 p. 123 Raptor Research 13(4): 123 124 RAPTOR RESEARCH Vol. 13 No. 4 ANNOUNCEMENTS Hawk Mountain Sanctuary Association is seeking an Executive Director in order to expand its programs in conservation and raptor biology. Some management expe- rience is preferred. For further information, send your curriculum vitae to Dr. Frank B. Gill, Academy of Natural Sciences of Philadelphia, Philadelphia, Pa. 19103. The United States Fish and Wildlife Service (USFWS) has recently established a Branch of Forensic Science to provide technical and scientific support to the Ser- vice’s Law Enforcement Division. The USFWS’s Division of Law Enforcement is assigned the responsibility of in- vestigating the illegal possession, killing, processing, importing and exporting of birds, fish, reptiles, and mammals relating to interstate and foreign commerce, treaty en- forcement, and national property. Much of this work deals with animals that appear on the Endangered Species List. To support this task, the Forensic Science Branch will direct its resources toward the identification of animals, animal parts (skins, blood, hair, bones, feathers, etc.), and animal products. Inasmuch as there are in excess of 430 mammals, birds, fish, and reptiles on the Endangered Species List alone (which is, unfortunately continuing to grow), it would be clearly impossible (or at least unreasonably expensive) to staff a lab with the fo- rensic/biological zoological experts necessary to identify parts and products from all of the animals which might be involved in a case. Instead, we hope to locate and list experts who are capable and willing to examine such evidence on a mutual aid, fee, or contractual basis. The examinations, of course, may necessitate testimony in a court of law. In addition, we will try to develop, or continue to encourage, interest by univer- sities and research centers in conducting research on current wildlife identification problems— particularly those involving endangered species animals, animal parts, and products. If any members of your organization have any questions, suggestions or information regarding our program, are interested themselves, or know of someone who would be interested and qualified in working wildlife identification problems, please contact the U.S. Fish and Wildlife Service at the address listed below. A survey form will be mailed immediately to requesting individuals, data from which will be used to com- pile a directory of available scientific expertise in wildlife identification. Ken Goddard, Chief Branch of Forensic Science Division of Law Enforcement U.S. Fish & Wildlife Service P.O. Box 19183 Washington, D.C. 20036 Telephone: (202) 343-9242 Winter 1979 125 HAWK TRUST NEWS The last six months have been busy ones for the Hawk Trust. The aviaries and birds are, hopefully, soon to be moved from Hungerford to a new site in Shropshire on the border between England and Wales where there is scope for further expansion. With eight species of raptor regularly nesting near the new headquarters, some in good num- bers, there will be excellent opportunities for carrying out combined field and labora- tory studies. On November 4, 1978, the Trust held a conference on the “Behavioural Ecology of Birds of Prey” at the meeting rooms of the Zoological Society of London. Papers includ- ed “A Study of Polygyny in Hen Harriers in Orkney” by Mr. N. Picozzi, “Patterns of Predation by Peregrines Breeding in Northern Scotland” by Mr. D. Weir, “Territory Usage by Tawny Owls” by Dr. A. R. Hardy, “The Role of Vultures as Scavengers” by Dr. D. Houston, and “The Hunting Strategies of Raptors” by Dr. N. Fox. There were also several short communications on more general aspects. It was an interesting and enjoyable day and drew raptor enthusiasts from far and wide together under one roof to discuss recent advances. Details of the proceedings of the conference, which will be published in 1979, can be obtained from the Hawk Trust, P.O. Box I, Hungerford, Berk- shire RGI7 OQE. Research during the last year has concentrated mainly on the bioenergetics of the Kestrel and on the growth and development of this and other species, but other studies have been undertaken including a bacteriological and haematological survey. This year the Trust successfully bred Kestrels ( Falco tinnunculus). Buzzards ( Buteo buteo ), Snowy Owls ( Nyctea scandiaca ), and Tawny Owls ( Strix aluco) in connection with research projects. James S. Kirkwood ABSTRACTS OF THESES AND DISSERTATIONS NOCTURNAL, PREROOSTING AND POSTROOSTING BEHAVIOR OF BREEDING ADULT AND YOUNG OF THE YEAR BALD EAGLES (HALIAEETUS LEUCOCEPHALUS ALASCANUS) ON THE CHIPPEWA NATIONAL FOREST, MINNESOTA. Nocturnal roosting behavior of nesting Bald Eagles and associated young of the year was studied during the 1974-1976 nesting seasons within the 6,475 km 2 Chippewa Na- tional Forest in Minnesota. Direct observations of 14 patagial color tagged young, 2 ra- dio tagged young, and adults from 8 nesting efforts were made at and away from nest trees during nocturnal, twilight, and diurnal time periods. Roosting behavior of eagles closely coincided with nocturnal time periods defined by the nautical twilight standard (sun 12° below horizon). Eagles were inactive (as recorded via Noctron IV night vision scope) during these roosting periods. Multiple regression analysis determined that length 126 Vol. 13 No. 4 of twilight, cloud cover, and presence of a full moon were significant factors (P<0.01) influencing the timing of eagle roosting relative to sunrise and sunset. These factors, all affecting relative light intensity, accounted for 72% and 68% of the variability in the timing of first morning activity and last evening activity, respectively. Higher ambient light conditions relative to sunrise or sunset (as indicated by long twilight period, lack of cloud cover, or presence of a full moon) resulted in later initiation of roosting in the evening and earlier termination of roosting at dawn. Temperature, nest site, and age of the eagle (adult or young) did not significantly (P<0.05) affect the timing of roosting behavior. Observations indicated that a single adult roosted at the nest tree until nest- lings were approximately 7 weeks old, at which time adult nest-tree roosting behavior terminated at all nests. From incubation to the fledging of young, adult roost locations away from the nest tree were primarily at repeatedly used supercanopy trees within 400 m of the nest. Fledgling eagles, including siblings, differed considerably regarding use of the nest tree for roosting. Nest trees continued to be important roosting locations for some fledglings through the first few weeks after their first flight. With progress of the nesting cycle, adults and fledglings roosted at increasingly greater distances from the nest tree. However, 4 weeks after their first flight, some fledging roost locations still ranged to within 12 m of the nest tree. Adults roosted to 1,866 m and fledglings as far as 3,057 m from the nest tree prior to dispersal of the young from the forest. After fledgl- ing, siblings showed a slight tendency to roost together (29 of 115 observations), this behavior occurring primarily in recently fledged young. Adults rarely were observed roosting with fledged young (2 of 102 observations). Characteristics of 44 identified roost trees were variable regarding species, height, distance to water, and community type. However, most roosts occurred on habitat edges (55%) and had considerable fo- liage (89%). Based on observed relative use of identified roosts in this study, identi- fication and protection of actual and potential important roosts within other eagle nest- ing territories appear practical within only a 400-m zone around nest trees. Pramstaller, Michael E. 1977. Nocturnal, preroosting and postroosting behavior of breeding adult and young of the year Bald Eagles ( Haliaeetus leucocephalus alas- canus) on the Chippewa National Forest, Minnesota. M.S. thesis, University of Minnesota, St. Paul. 97 pp. Present address: Michael E. Pramstaller Raptor Information Center National Wildlife Federation 1412 16th Street, N.W. Washington, D.C. 20036 BOOK REVIEWS A symposium on African predatory birds. 1977. South African Ornithological Society. 108 p. Paper covers. Price (unstated). Obtainable through Northern Transvaal Orni- thological Society, P.O. Box 4158, Pretoria 0001, South Africa. This collection of papers was presented at the 1977 Symposium on African Pre- Winter 1979 127 datory Birds. The contents consist of 11 papers printed in full text and 16 papers rep- resented by title and abstract. The opening addresses set the tone for the symposium, with Ian Newton discussing population regulation in diurnal birds of prey (abstract only) and Leslie Brown providing a comprehensive summary of the current knowl- edge about all species of African birds of prey. The topics of other papers for which the full text is provided are classified into three categories: predatory behavior, predator biology, and predator conservation. Predatory behavior is represented by one interesting paper which compares the prey and foraging methods of the terrestrial hunting Ground Hornbill and the Secretary Bird. Articles about predator biology include an ecological comparison of four sympa- tric owl species in Transvaal, South Africa, and papers on aspects of the general ecol- ogy of the Long-crested Eagle, Mackinder’s Eagle Owl, Dickinson’s Kestrel, and Greater Kestrel. Also there is a comprehensive paper on the various raptor measure- ments used to document aspects of bird design. Articles about predator conservation include a comparison of Black Eagle populations in protected and unprotected areas, a status report on the raptors of the Eastern Cape, South Africa, and a description of raptor leg surgery. Papers read at the symposium that are represented only by ab- stracts cover a wide variety of topics including, for example, the food resources of two sympatric Phoebetria albatrosses, Bat Hawk feeding behavior, Snake Eagle biolo- gy, Peregrine Falcons in Victoria, Australia, and several reports on Cape Vulture re- search. The primary value of this publication is that it provides the reader with a spec- trum of the types of avian predator research which are currently being pursued in Africa by many of the continent’s leading raptor biologists. For persons seriously in- terested in African raptor research, this publication offers an opportunity to obtain a series of generally good papers on research currently in progress. Thomas L. Thurow Bird of Prey Management Techniques. 1978. T. A. Geer (ed). A symposium spon- sored by the International Association of Falconry and Conservation of Birds of Prey. 160 pp. Price not stated. (Available through T. A. Geer, Minor Road, Brewster, New York 10509.) Because research on birds of prey has undergone a rapid growth in the past decade, the number of symposia treating them has likewise increased. These symposia tend to treat specific topics, and this symposium has brought together a truly international group of individuals concerned with the problems of management. The meetings were held at Wadham College, Oxford, England. In all, 202 participants are listed represent- ing some 20 countries, although Europeans were in the majority. There are five major areas of discussion, and each area had several contributing papers. These areas are (1) Population Dynamics and Habitat Management, (2) Reducing Mortality in the Wild, (3) Increasing Productivity in Wild Populations, (4) Captive Breeding and Release as Man- agement Techniques and (5) General Considerations (a discussion of falconry, legal and economic problems). Of the 17 papers published in this volume, most appeared to offer new material although two were taken from Endangered Species (S. A. Temple (ed.) 1978.). 128 Vol. 13 No. 4 Some of the papers, while of general interest, report on projects of regional scope such as the Project Eagle-Owl, South West, which describes the introduction of Eagle Owls in a small area of southwestern Sweden. Others, Productivity Manipulation in Wild Eagles, as an example, are review papers of a general nature. The opening address by T. Lutz, president of IAFCBP, sets the tone of the conference and reminds us that birds of prey have a variety of meanings to us all. We frequently need this reminder, and thus I quote from his address: “One has an admiring, revering love for them, the other loves them as a scientific object, another loves them as a possession, and yet others find the fulfillment of their love in the partner relationship with them.” All are valid viewpoints. All in all the proceedings of this conference are recommended highly. C. M. White Hawks and Owls of North America. D. S. Heintzelman. 1979. Universe Books, New York. 197 pages. 8 color plates, many black and whites. $18.50. Donald Heintzelman is a well-known author to most people interested in raptors and has produced another fine book to add to his list of quality works. In the preface, the author states that Hawks and Owls of North America is not written on a professional level, but rather, is a guide for the general public. To those familiar with Heintzelman’s other books, this style is probably his hallmark. The subtitle of this book is “A Complete Guide to North American Birds of Prey,” and indeed, the list of included raptors is exhaustive. For example, the roadside hawk (. Buteo magnirostris) is discussed, even though Heintzelman documents it as being seen only once in North America. The description given for each species varies greatly, but generally includes information on nesting, feeding, identifying features, and unique characteristics. I can forsee some criticism about the amount of space given to some birds while others seem neglected, as with the eight pages describing the osprey com- pared to the fewer than four pages devoted to the red-tailed hawk. Chapters are divided taxonomically, plus Heintzelman includes several short sections on topics such as ecology, migration, and conservation. An appendix, listing raptor re- lated organizations, is included as well as a seven-page list of selected references. Over- all, the book is well written and interesting, and would be a nice addition to the book- shelf of anyone interested in hawks and owls. William K. Parker THE RAPTOR RESEARCH FOUNDATION, INC. OFFICERS President Dr. Richard R. Olendorff, Division of Resources (C-932), 2800 Cottage Way, Sacramento, California 95825 Vice-President Dr. Joseph R. Murphy, Department of Zoology, 167 WIDB, Brigham Young University, Provo, Utah 84602 Secretary Dr. Donald R. Johnson, Department of Biological Sciences, Univer- sity of Idaho, Moscow, Idaho 83843 Treasurer Dr. Gary E. Duke, Department of Veterinary Biology, College of Veterinary Medicine, University of Minnesota, St. Paul, Minnesota 55101. Address all matters dealing with membership status, dues, publication sales, or other financial transactions to the Treasurer. Send changes of address to the Treasurer. Address all general inquiries to the Secretary. See inside front cover for suggestions to contributors of manuscripts for Rap- tor Research, Raptor Research Reports, and special Raptor Research Foundation publications. BOARD OF DIRECTORS Eastern Dr. Mark R. Fuller, Migratory Bird Lab., U.S.F.W.S., Patuxent Re- search Center, Laurel, Maryland 20811 Central Dr, James Grier, Department of Zoology, North Dakota State Uni- versity, Fargo, North Dakota 58102 Pacific and Mountain Dr. Joseph R. Murphy, Department of Zoology, 167 WIDB, Brigham Young University, Provo, Utah 84602 Canadian Eastern: Dr. David Bird, Macdonald Raptor Research Center, Mac- donald College, Quebec, H9X ICO, Canada Western: Dr. Wayne Nelson, 620 Harris Place Northwest, Calgary, Al- berta, T3B ZV4, Canada At Large Dr. Stanley Temple, Department of Wildlife Ecology, Russell Lab- oratory, University of Wisconsin, Madison, Wisconsin 53706 At Large Dr. Thomas Dunstan, Biology Dept., Western Illinois University, Macomb, Illinois 61455