Introduced Animals in the Diets of the Ogasawara Buzzard, an Endemic Insular Raptor in the Pacific Ocean

Home , Chichijima, Hahajima, Hawaiian hawk, Japanese wood pigeon, Wildlife of Japan

JUNE2005 SNORTCOMMUNiCaTiOnS 173

OSTERLOFF,S. 1977. Migration,wintering areas, and site SWENSON,J.E. 1979.The relationshipbetween prey spe- tenacity of the European Osprey,Pandion haliaetus ha- cies ecologyand dive successin Ospreys.Auk 96:408- liaetus(L.). Ornis Scan&8:60-78. 412. PREVOST,Y. 1982. The wintering ecologyof Osprey in Se- THIBAULT,J.-C., R. TRIAY,P.L. BEAUBRUN,D. POUKHALFA, negambia. Ph.D. dissertation, Univ. Edinburgh, Ed- J.-M. DOMINICI,AND A. TORRE.1996. Osprey (Pan&on inburgh, U.K. haliaetus) in the Mediterranean: characteristics of a P•WSON,D.S. 1952. Mean depth and the fish production resident population with a patchy distribution. Pages of large lakes. Ecology33:513-521. 135-144 inJ. Muntaner andJ. Mayol lEDS.], Ecolog•a RmER, R.A. 1982. The morphoedaphic index-use,abuse, y conservacion de las rapaces Mediterraneas. SEO, and fundamental concepts. Trans.Am. Fish. Soc.111: Madrid, Spain. 154-164. V2u,•D)d•LE, LJ 2U,•DH.A. V2U,•D)d•L•. 1982. Factors af- SANCHORo¾o, F. aND C. GP,•tN•.DOS.1988. La pesca en los embalses andaluces. Instituto de Desarrollo Re- fecting the productivity of Ospreys nesting in west- central Idaho. Condor 84:292-299. gional de la Univ. Sevilla,Sevilla, Spain. V2U,•A-MtLL•R,S.L. 1987. Habitat suitabilityindex models. S^URODt,P. 1994. African non-breeding areas of Fenno- scandianOspreys (Pandion haliaetus). Ostrich 65:127- Osprey. U.S. Fish and Wildlife Service, Washington, DC U.S.A. 136. STATISTICA. 1986. Version 5. StarSoft, Inc., Tulsa, OK U.S.A. Received 11 February 2004; accepted 5 March 2005

j. RaptorRes. 39(2):173-179 ¸ 2005 The Raptor ResearchFoundation, Inc.

INTRODUCED ANIMALS IN THE DIETS OF THE OGASAWARABUZZARD, AN ENDEMIC INSULAR RAPTOR IN THE PACIFIC OCEAN

YUKA KATO 1 AND TADASHI SUZUKI Departmentof BiologicalSdences, Tohyo Metropolitan University, Minami-ohsawa 1-1, Hachi-ohji, Tohyo192-0397Japan

KEYWORDS: CommonBuzzard; Buteo buteo toyoshimai; tal changes as are many other insular predators (e.g., gnsularsubspecies; diet;, introduced animals; Bonin Islands; Cade andJones 1993). Therefore, ecologicalinformation OgasawaraIslands. including dietary data are needed to develop conservation strategiesfor the population. However, little infor- The Ogasawarabuzzard (Buteobuteo toyoshimai) is an mation on the food habits of the Ogasawarabuzzard are •nsular subspeciesof the Common Buzzard (B. buteo),en- currently available. demic to the Ogasawara (Bonin) Islands, in the Pacific Many researchershave investigatedthe diet of the con- Ocean (Momiyama1927, Ornithological Society of Japan tinental subspeciesof the Common Buzzard, especially 2002). This hawk may be distinguishedfrom a closely- in Europe. As a result, the Common Buzzard is well related subspecies,the Japanese Common Buzzard (B. known to capture and consume various kinds of inver- buteojaponicus), by its lessbrown or lighter plumage, a tebrates and small- to medium-sized vertebrates. Com- longer bill, and shorter wings and tarsi (Momiyama mon prey include reptiles, birds, and rodents depending 1927). The distributionof the Ogasawarabuzzard is very on environmental conditions (e.g., Cramp and Simmons restricted, and this hawk is classifiedas endangered in 1980, del Hoyo et al. 1994, Jedrzejewski et al. 1994, Japan (Ministry of Environment 2002). Recently,Suzuki Swann and Etheridge 1995, Reif et al. 2001, Sergio et al. and Kato (2000) reported on the abundance of the Oga- 2002). sawara buzzard on Chichijima, and estimated that less The native fauna of the Ogasawara(Bonin) Islandswas than 85 pairs of this subspeciesinhabited the Ogasawara originally characterized by low speciesrichness because Islands. of the island'svolcanic origin, and its small size and rel- Insular raptors are likely to be sensitiveto environmen- atively great distance from the other islands and mainland of Japan (Tsuyamaand Asami 1970). Human colo- • Email address:[email protected] nization of the islands began in the 1830s. After that 174 SHORT COMMUNICATIONS VOL. 39, NO. 2

ume, it was likely that a number of exotic animals were introduced intentionally or unintentionally. Some of these introduced specieshave become very common. Conversely,many native animals have become extinct. For example, about a third of breeding land birds have gone extinct (Ornithological Societyof Japan 2002). As a result, the present fauna of the OgasawaraIslands is composed of a mix of introduced exotic speciesand some survivingnative species. Several authors have incidentally reported that the Ogasawarabuzzard consumed rodents, some birds, green anoles (Anolis carolinensis),and marine toads ( Bufo maN- nus;Takano et al. 1970,Wild Bird Societyof Japan 1975, Nakane et al. 1980, Ueda and deforest 1988, Suzuki and Chiba 1995, Kawakami2000). Villagers alsoreported that this buzzard preyed upon domesticfowls (Suzuki 1982) and migrant egrets (Egrettasp. and Bulbulcusibis; Y. Iida pers. comm.). Despite these anecdotalreports, the food habits of the Ogasawarabuzzard have not received any ßr' , 3p_]?he quantitativestudy. Here, we provide quantitativedata on the diet of the Ogasawara buzzard, derived from a broader ecological study of this endemic insular raptor. We also describe ,• (Bonin)IIa•ds someof the basicecology of this species,information that is necessaryto provide for its conservation.

METHODS

Study Area. The Ogasawara(Bonin) Islands are composed of three island groups and situated in the Pacific 13• 140151 Ocean, ca. 1000 km south of the mainland of Japan (Fig. 1). It has a volcanicorigin and subtropicalclimates, with Figure 1. The location of the study area, Ogasawara an annual mean temperatureand rainfall of 23.0øCand (Bonin) Islands. 1333 mm, respectively(means from 1986-99 at Chichi- j•ma Observatory). Chichijima (ca. 27øN,142øE), where we studiedthe diets of the Ogasawarabuzzard, is the largest island of the Introduced animals (Table 1; see Tomiyama1998) are OgasawaraIslands and 24 km2 in area with a high ele- very common now in the islands as well as introduced vation of 326 m. Chichijima was extensivelydeforested invertebrates,such as European honeybees(Apis melh- from the late 1880s to the mid 1900s (Katahira 1981). fera) and African giant snails (Achatinafulica). Norway Today,Chichijima is generallycovered with relativelylow rats (Rattusnorvegicus) have also been recorded as intro- vegetation.About 73% of Chichijima is regeneratedna- duced rodents on the OgasawaraIslands, but recently uve forests and scrubs, and the rest includes coastal for- have not been found in Chichijima. ests, exotic low shrubs (Leucaenaleucocephala), grasses Data Collection. Data were collected by two methods: (Stachytarphetajamaicensis), and residentialareas; canopy (1) observationof hunting or carrying behaviorby buz- trees in all areasconsist of native and introduced species zardsfrom fixed points and (2) observationat nestsites that do not exceed 15 m in height (Shimizu and Tabata We conductedgeneral behavioralobservations, prey-car- 1991). rying and hunting behavior for 491 hr in January-June Land Animals on Chichijima. In addition to the extant in 2000, 543 hr throughout 2001, and 668 hr in 2002. native migratory and introduced land vertebrates in We alsoincluded opportunisticobservations in 1998 and Chichijima (Table 1) and accidental visitors of birds, 1999. The buzzards were observed with binoculars (8X) some breeding seabirdsare also found on the islands. and/or a telescope(60X). We pooled all data, because Nonbreeding visitorsare infrequent and breeding sea- sample size in each year was small. We observedfour birds occur in a relativelyrestricted seasonof the year nestson cliffs during 148.9 hr in May-June in 2000 and depending on the species(e.g., Momiyama 1930, Chiba one nest for a total of 28.8 hr in May-June in 2001. We and Funatsu 1991, Ornithological Societyof Japan 2002, watched those nests from hides, which were more than Kato pers. observ.). 300 m away.Prey items brought to the nestswere iden- The native land invertebratesinclude about 236 spe- tified with a telescope(60X). We took care not to disturb cies of insects and 63 speciesof land snails, although the nestingactivity; we generallystopped the observation many of these have exhibited declines in numbers or al- when a parent on the nest noticed us, or a parent outside ready have gone extinct (Kurozumi 1988, Kato 1991). the nest displayed an alarm for more than 5 min. Data JUNE 2005 SHORTCOMMUNICATIONS 175

Table 1. Presentfauna of resident land vertebrateson Chichijima, the Ogasawara(Bonin) Islands.

SPECIES STATUS 1

Mammals Ogasawarafruit bat (Pteropuspeslaphon) Native Feral goat (Capra hircus) Introduced Feral cat (Felis catus) Introduced Black rat (Rattus rattus•) Introduced House mouse ( Mus musculus) Introduced

Birds Brown-cheekedBulbul ( Hypsipetesamaurotis) Native Bull-headed Shrike ( Lanius bucephalus) Recent immigrant Bush Warbler (Cettia diphone) Native Japanese White-eye (Zosteropsjaponicus) Introduced Rock Thrush ( Monticola solitarius) Native White's Ground Thrush (Zootheradauma) Recent immigrant JapaneseWood Pigeon (C01umbajanthina) Native Common Buzzard ( Buteo buteo) Native Rep61es Ogasawarasnake-eyed skink (Crypt0blepharusboutonii) Native Green anole (Anolis carolinensis) Introduced House gecko (Hemidactylusfrenatus) Introduced Morning gecko ( Lepidodactyluslugubris) Introduced Brahminy blind snake (Typh010psbraminus) ? Amphibians Marine toad (Bufo marinus) Introduced Categorizationsare referredfrom Tsuyamaand Asami(1970), and the OgasawaraNatural Environment Study Group (1992). Another introducedrat, R. norvegicus,formerly resident, has not been found recently.

from nest observations were also combined because of speciesbecause all but one partial food item identified small sample sizesfor each nest. as a marine toad was large and determined to be an The two methods were not employed on the same day adult. in the same territory, which should have prevented the double countsof the sameprey items. For both methods, RESULTS we were usuallyable to identify prey animals, becauseall prey observed were likely specieson the limited list of We recorded 156 prey items using the two methods of terrestrial vertebrate fauna present in the OgasawaraIs- observations.Among them, we omitted from the analyses lands (Table 1). As black rats (R. rattus) and Norway rats 46 prey items that we could not identify. are similar in size and shape, it was possiblethat we mis- The Ogasawarabuzzard hunted or carried 49 prey took one speciesfor the other. However,several sampling items, and 40 of them were identified (Table 2). Black surveyshave been unable to document Norway rats on rats (N = 23, 57.5%) and green anoles(N = 9, 22.5%) Chichijima (e.g.,Yabe and Matsumoto1982, K. Watanabe pers. comm., pers. observ.). Therefore, we assumedthat predominated in this sample. Marine toads (N = 2, the black rat were the only large rodent prey taken by 5.0%) and petrels( Bulweriabulwerii or Oceanodromasp.; N buzzardsand that Norway ratswas inconsequential in the = 2, 5.0%) were next most frequent. A house mouse diet of this hawk. (Mus musculus)and a White's Ground Thrush (Zoothera In order to evaluate the relative importance of prey dauma)were also observed(N = 1, 2.5%, respectively). speciesas in the diet on a biomassbasis, we weighed One small- or medium-sized bird (2.5%) and one lizard dominant prey speciesusing specimenscollected by us (2.5%) were alsorecorded as prey, though we could not tn Chichijima in 2001. Twenty-three black rats were identify these to the specieslevel. caught with live traps in August-October,along with 29 We recorded 35 (87.5%) of the 40 identified prey green anoles, and 32 marine toads caught by hand in April-May and on 16 September,respectively. As marine items during January-Junewhen the Ogasawarabuzzard toadswere caughtaround a flume where many toadscon- engagesin breedingactivities. Six (17.1%; all were black gregated for mating in the night, they were considered rats) of the 35 prey items were used for flight displayby all adults. Adult biomasswas appropriate for this prey territorial males.Two birds (one thrush and one petrel, 176 SHORT COMMUNICATIONS VOL. 39, NO. 2

Table 2. Diets of the Ogasawarabuzzards observed in Chichijima (1998-2002). Prey items identified at the class level were shown. a

No. OBSERVED

HUNTED OR OBSERVED PREY CARRIED AT NEST TOTAL PERCENT

Mammals Black rat (Rattus rattus) 23 32 55 50.0% House mouse (Mus musculus) 1 0 1 0.9%

Birds White's Ground Thrush (Zootheradauma) I I 2 1.8% Petrel b 2 0 2 1.8% Small- to medium-sized birds c I 3 4 3.6% Reptiles Green anole (Anolis carolinensis) 9 27 36 32.7% Unknown I 0 I 0.9% Amphibians Marine toad (Bufomarinus) 2 7 9 8.2% Total 40 70 110 100.0% Forty-sixanimals (9 observedhunting and 37 prey deliveries)were excludedfrom the table becausetheir identitywas uncertain. Bulweriabulwerii or Oceanodromasp. Small-to medium-sizedbirds include Zosteropsjaponicus, Cettia diphone, Hypsipetes amaurotis, Lanius bucepharus, Monticola solitarius, and Zoothera dauma.

5.0%) werefed to fledglings.Though we couldnot follow To evaluate the relative importance of each prey spe- the fate of the remaining prey, five (14.3%) of the 35 ciesas foods, we took bodymass into consideration.Many were likely brought to the nests based on the flight di- black rats (i = 114.5 + 44.2 g [SD], range = 50-180 g, rection of the breeding Ogasawarabuzzard. Other prey N = 23) and marine toads (i = 91.6 + 36.8 g, range = seemed to be also used for breeding activities (fed to 35-205, N = 32) were more than 100 g, but all green mates and/or offspring) rather than for self consump- anoles (i = 6.0 --- 1.6 g, range = 3.0-9.5, N = 29) were tion. lessthan 10 g. Total biomassconsumed during observa- We recorded107 prey items during the nest site ob- tion was 6298 g for black rats, 216 g for green anoles, servations.Sixteen of the prey items were alreadyon the and 824 g for marine toads. nestswhen we began the observations.We observedthat 101 (94.4%) of the 107 prey items were consumedby DISCUSSION either nestlingsor the female. Six other items were carried off from the nests by the female parent after the During this study,we documented the current food nestlingstopped feeding. habits of the Ogasawarabuzzard, an insular endemic sub- We identified 70 (65.4%) of the 107 prey items ob- species.The number of speciestaken wasvery small (Ta- servedat nest sites(Table 2). Among them, blackrats (N ble 2) comparedwith other populationsof the Common = 32, 45.7%) and green anoles (N = 27, 30.6%) were Bttzzard (e.g., Cramp and Simmons1980). The main rea- dominant,followed by marine toads(N = 7, 10.0%).The son for this differencewas undoubtedly the low diversity remaining prey itemswere small-to medium-sizedbirds. fauna inhabiting the OgasawaraIslands (Table 1). The We combined the data collected by the two different Ogasawarabuzzard primarily caught black rats, green methods,because the prey compositionbetween the two anoles, and marine toads, all of which were introduced methodswas not significantlydifferent (X2 = 4.13, df = animals in the OgasawaraIslands (Tomiyama 1998). 3, P = 0.24). Based on the pooled sample,we identified These three speciesaccounted for ca. 90% of prey items 110 prey items. There were three predominant species in terms of frequency (Table 2). Black rats are known to in the diet; black rats (N = 55, 50.0%), green anoles(N be common on many islandsof the Ogasawaraarchipel- = 36, 32.7%), and marine toads (N = 9, 8.2%; Table 2). ago. However, green anoles and marine toads are only In addition, we also collected eight pellets in fields inci- present and common on two major islands (Chichijima dentally during the study.All of thesecontained only the and Hahajima) of the Ogasawarachain. Based on the remnants of black rats. predominance of these three prey speciesin the diet of JUNE2005 SHORTCOMMUNICATIONS 177

Table 3. Possiblenative prey availablefor the Ogasawarabuzzard in the Ogasawara(Bonin) Islandsbefore coloni- zation by human beingsand exotic animals.a

SPECIES STATUS

Vertebrates Mammals Ogasawarafruit bat (Pteropuspeslaphon) Endangered Birds Brown-cheekedBulbul ( Hypsipetesamaurotis) Bush Warbler (Cettiadiphone) Bonin White-eye (Apalopteronfamiliare) Extinct in Chichijima Rock Thrush (Monticola solitarius) Bonin Islands Thrush (Chichlopasserterrestris) Extinct Oriental Greenfinch (Carduelis sinica) Extinct in Chichijima Bonin Islands Grosbeak (Chaunoproetusferreorostris) Extinct Jungle Crow (Corvusmacrorhynchos) Extinct Bonin Wood Pigeon (C0lumbaversicolor) Extinct JapaneseWood Pigeon (C0lumbajanthina) Endangered Rufous Night Heron (Nycticoraxcaledonicus) Extinct Small- to medium-sizedsea birds (e.g., Bulweria,Oceanodroma) Occasionalmigrant visitors(e.g., Ardeidae, Charadriidae,Scolo- pacidae, and passerines) Reptiles Ogasawarasnake-eyed skink (Crypt0blepharusboutonii) Green turtle ( Cheloniamydas) Invertebrates Large insects(e.g., Cicadidae,Buprostidae) Land crabs (Geograpsus,Sesarma) and hermit crabs (e.g., Coenobi- ta) Large land snails (e.g., Mandarina) extinct or endangered depending on species) Extinct or Endangered Main sourcesare Tsuyamaand Asami (1970) and OgasawaraNatural EnvironmentStudy Group (1992). the buzzard, the densityof these three speciesappears to could be important prey at times for the Ogasawarabuz- be very high on Chichijima Island. zard. For example, the mean mass of six adult White's We observedthe Ogasawarabuzzard to prey upon only Ground Thrushes was 128 g (Y. Kato, unpubl. data). few birds (Table 2). The birds appeared to be auxiliary We also observedthe Ogasawarabuzzard preying upon food for buzzard on Chichijima Island during this study. seabirds(e.g., petrels;Table 2), which are generallylarge But other researchershave reported some birds as prey compared with passerines.The OgasawaraIslands are of the Ogasawarabuzzard. Ueda and deforest (1998) known as breeding grounds of seabirds(e.g., BulwersPe- found that the JapaneseWhite-eye (Zosteropsjaponicus) trel [ Bulweriabulweriz] , Wedge-tailed Shearwater [Puffinus was prey for the buzzard in Chichijima and Kawakami pacificus],Brown Noddy [Anousstolidus], and Brown Boo- (2000) recorded the White's Ground Thrush, Pacific by [Sula leucogaster];Ornithological Society of Japan Golden Plover (Pluvialis dominica), and Providence Petrel 2002). We observed that three pairs of the Ogasawara (Pterodromahypoleuca) in the diet on Hahajima. Further- buzzard had breeding territories that included seabird more, the Ogasawarabuzzard was reported by villagers breeding colonieson the isletsnear Chichijima (Y. Kato, to hunt migrant egrets (Y. Iida pers. comm.). unpubl. data). These three territories were not included The Common Buzzard is known to prey frequently in our nest-sitestudies. As breeding Ogasawarabuzzards (e.g., Cramp and Simmons1980) and selectively(Jedrze- seem to hunt only within their territories, it wasnot sur- jewskiet al. 1994) on medium-sizedbirds. The Ogasawara prising our list of the prey specieswas limited to land buzzard also hunted White's Ground Thrushes.We sug- fauna. Thus, our data may have underestimated buzzard gest that medium-sizedbirds, especiallyfledglings and predation on seabirdsby excluding territories without large nestlingsbecause of their relativelylarge body mass, seabird colonies. 178 SHORTCOMMUNICATIONS VOL. 39, No. 2

The number of marine toads (/= 91.6 g) taken was ACKNOWLEDGMENTS lessthan that of green anoles recorded (Table 2). How- We thank K. Morimoto, N. Kachi, H. Chiba, and the ever, the biomass of marine toads was more than 10 times staff of the Institute of Boninologyfor their helpful in- that of green anoles (œ = 6.0 g). Thus, we suggestthat formation and field support.A. Suzukikindly informed marine toads may be the more important prey for Oga- us of the massof green anoles before we took our own sawarabuzzards. Of course,green anoles might also be measurements.We also thank three anonymousreferees an important food if frequent feeding providesthe buz- for their helpful advice that improved this manuscript. zards with stable nutrition. This studywas partially supportedby the ResearchPro- During the studyperiod, the Ogasawarabuzzard large- ject on ConservationMethods of SubtropicalIsland Eco- ly fed on introduced vertebrates.This dietary pattern is systemscoordinated by S. Nohara and fundedfrom Japan Environmental Agency and a public trust Zoshinkai Na- similar as reported in the Hawaiian Hawk (B. solitarius) ture and Environmental Conservation Research Grant. in the Hawaiian Islands (Griffin et al. 1998). These re- suits indicated that the endemic buzzardssurviving on LITERATURE CITED selectedislands, with drasticallymodified environments, in the Pacific Ocean now feed on exotic animals intro- C•a)E,T.J. •4t) C.G. JONES.1993. Progressin restoration of the Mauritius Kestrel. Conserr. Biol. 7:169-175. duced by human beings. Then, what animalsdid the Ogasawarabuzzard feed on CHIB^,H. ANt)T. FUN^TSU.1991. Birds in Chichijima-ret- before the arrival of introduced animals? Based on the to and Hahajima-retto.Pages 135-147 in M. Ono, M knowledgeof the current food habits of the Ogasawara Kimura, K. Miyashita,and M. Nogami [Et)s.], Reports buzzard and of the continentalCommon Buzzard (e.g., of the secondgeneral surveyof natural environment Cramp and Simons1980), we can speculateabout the his- of the Ogasawara(Bonin) Islands.Tokyo Metropoli- torlcal diet of this species.We suggestthat the former diet tan Univ., Tokyo, Japan. of this buzzard consisted of several medium-sized birds, a CRAMP,S. AND K.E.L. SIMMONS.(Er)s.). 1980. Handbook couplereptiles, some large invertebrates,and perhaps,the of the birds of Europe, the Middle East and North Ogasawarafruit bat (Pteropuspeslaphon; Table 3). Africa. Vol. 2. Oxford Univ. Press, Oxford, U.K. The Common Buzzard is known to switch from one r)ELHoYo, J., A. ELLIOTt, ANt)J. SA•½ATA[.(Et)s.). 1994. speciesof primary prey to another depending on their Handbook of the birds of the world. Vol. 2. Lynx Edi- abundance (Truszkowski 1976, Reif et al. 2001, Selas tions, Barcelona,Spain. 2001). In the OgasawaraIslands, about a third of native GraFFIN, C.R., P.W.C. PATON, AND T.S. BASKETr. 1998. land bird specieshave expired since the human coloni- Breeding ecology and behavior of the Hawaiian zation (Ornithological Society of Japan 2002), and the Hawk. Condor 100:654-662. abundance of native animals have generally decreased JEDRZEJEWSKI,W., A. SZYMURA,ANt) B. JEDRZEJEWSKA.1994. and many of them are threatenedwith extinction (Tsuy- Reproduction and food of the buzzard Buteobuteo in ama and Asami 1970). On the contrary,the number of relation to the abundance of rodents and birds in speciesand the densityof introduced animals increased. alowieza National Park, Poland. Ethol. Ecol. Evol. 6: The predominance of introduced animalsin the present 179-190. dietsof the Ogasawarabuzzard has probably been caused KATAHIRA, H. 1981. The characteristics of land use in by the shift in prey availability. Chichijima island, the Ogasawaraislands. Pages 43-

ANIMALES INTRODUCIDOS EN LA DIETA DE BUTEO BUTEO TO- 63 in The general surveyof natural environment of YOSHIMAI,UN Aw R•z ENDI•MICA ALAS ISLASDEE OCP.ANO the Ogasawara(Bonin) Islandsresearch group of To- PACiFICO kyo Metropolitan University lEDs.], Reports of the general surveyof natural environment of the Ogasa- RESUMEN.--Buteobuteo toyoshimai es una subespecieinsu- wara (Bonin) Islands.Tokyo Metropolitan Univ., To- lar endSmicadistribuida exclusivamente en las islasOga- kyo,Japan. sawara(Bonin), en el Ocfiano Pacifico subtropical.Esta I•TO, M. 1991. A list of insectsfrom the OgasawaraIs- subespeciese considera amenazada en Jap6n. La ecolo- lands. OgasawaraRes. 17/18:32-59. gia de estarapaz, incluyendosus hSbitos alimenticios, ha KAWAK•MI, K. 2000. Bird deaths in the Bonin Islands. An- sldo poco investigada.En este estudio examinamoscuan- imals and Zoos 52:12-16. titativamente su dieta mediante observaciones directas realizadasentre 1998-2002 en Chichijima, la isla de may- KUROr)^,N. 1930. The geographicaldistribution of mam- or 5rea (ca. 24 km2) entre lasislas Ogasawara. Las presas mals in the Bonin Islands.Bull. Biogeog•Soc. Japan 1: 81-88. fueron registradas mientras las aves estaban cazando, mmntrasaves adultas las cargaban o cuandoeran 11evadas KUROZUMI,T. 1988. Speciescomposition and abundance a los nidos. De los 110 items identificados, 55 (50.0%) of land mollusksand factorsaffecting their extinction correspondierona Rattusrattus, 36 (32.7%) a Andis car- in the Ogasawara(Bonin) Islands.Ogasawara Res. 14/ ohnensisy 9 (8.2%) a Bufomarinus. Con baseen la con- 15:59-109. tnbuci6n estimada en tfirminos de biomasa, R. rattus fue MINISTRY OF ENVIRONMENT. (EDS.). 2002. Threatened predominante, seguidapor B. marinus. wildlife of Japan -red data book. Japan Wild Research [Traducci0ndel equipo editorial] Center, Tokyo,Japan. JUNE2005 SHORTCOMMUNICATIONS 179

MOMIYAMA,t. 1927. Discriptionof twenty-fivenew birds --AND H. CHIBA.1995. Distribution and ecology of and three additions from Japaneseterritories. Annot. the Ogasawara Buzzard. Pages 61-93 in Tokyo Re- Orn. Or/ent. 1:81-101. gional Forest Office [EDs.], The Ogasawarabuzzard- 1930. On the birds of Bonin and Iwo-islands. report for conservation act of rare plants and animals Bull. Bioge%n:Soc. Japan. 1:89-186. Tokyo Regional Forest Office, Tokyo,Japan. NAKANE, g., t. MATSUMOTO, AND K. MIYASHITA. 1980. Sta- --AND Y. KATO.2000. Abundance of the Ogasawara tus of the birds on Chichi-jima and Haha-jima in the buzzard on Chichijima, the Pacific Ocean. J. Raptor OgasawaraIslands. Pages 43-63 in The general survey Res. 34:241-243. of natural environment of the Ogasawara(Bonin) Is- SWANN,R.L. AND B. ETHERIDGE.1995. A comparison of lands research group of Tokyo Metropolitan Univer- breeding successand prey of the Common Buzzard sity [EDS.], Reports of the general surveyof natural Buteo buteo in two areas of northern Scotland. Bzrd environment of the Ogasawara (Bonin) Islands. To- Study42:37-43. kyo Metropolitan University,Tokyo, Japan. TAKANO, S., Y. UCHIDA, N. YANAGISAWA,AND N. SUGIYAMA OGASAWARA NATURAL ENVIRONMENTAL GROUP. 1992. The 1970. The birds of the Bonin Islands and the Volcano nature of the OgasawaraIslands. Kokin-Shoin, Tokyo, Islands. Pages61-87 in Agency for Cultural Affairs Japan. (In Japanese.) [EDS.], Nature of the OgasawaraIslands. Agency for ORNITHOLOGICALSOCIETY OF JAPAN.2002. Check-list of Cultural Affairs, Tokyo,Japan. Japanesebirds. Ornithological Societyof Japan, Hok- TOMIYAMA,K. 1998. Disturbance of island ecosystemby kaido, Japan. introduced speciesin OgasawaraIslands. Jpn. J. Ecol, REIF, V., R. TORNBERG,S. JUNGELL,AND E. KORPIMAKI. 48:63-72. 2001. Diet variation of Common Buzzards in Finland TRUSZKOWSKI,J. 1976. Role of the Common Buzzard (Bu- supportsthe alternativeprey hypothesis.Ecography 24: teoIruteo L.) in agrocenosesof the middle Wielkopol- 267-274. ska. Pol. Ecok Stud. 2:103-111. SELAS,V. 2001. Predation on reptiles and birds by the TSUYAMA,T. ANDS. ASAMI.1970. Nature of the Ogasawara. Common Buzzard, Buteobuteo, in relation to changes Hirokawa Publishing Co., Tokyo, Japan. in its main prey,voles. Can. J. Zool.79:2086-2093. UEDA, K. AND L. N. DEFOREST. 1988. Food and behavior SERGIO,F., A. BOTO, C. SCANDOLARA,AND G. BOGLIANTI. of male Ogasawarabuzzards during the courtship 2002. Density, nest sites, diet, and productivity of feedingperiod. Jpn. J. Ornithol.37:34-36. Common Buzzards (Buteo buteo)in the Italian pre- WILD BIRD SOCIETYOF JAPAN.1975. Hahajima Islands. Alps.J. RaptorRes. 36:24-32. Pages 93-136 in Wild Bird Society of Japan IMps.I, SHIMIZU, Y. AND H. TABATA. 1991. Forest structures, com- Survey on special birds requiring protection. Japan position, and distribution on a Pacific island,with ref- Environment Agency,Tokyo, Japan. erence to ecologicalrelease and speciation.Pac. Sci. YABE,T. ANDT. MATSUMOTO.1982. A surveyon the ma- 45:28-49. rine rodents on Chichijima and Hahajima, the Oga- Suzur,I, T. 1982. Status of the Ogasawara buzzard on sawaraIslands. J. MammalSoc. Jpn. 9:14-19. Chichijima: estimation of distribution and abundance. Ann. Rep. OgasawaraRes. 6:23-34. Received 2 November 2003; accepted 4 October 2004

j. RaptorRes. 39 (2):179-183 ¸ 2005 The Raptor ResearchFoundation, Inc.

THE DIET OF EUP•S• GRIFFONS(GYPSFULVUS) IN CRETE

STAVROS M. XIROUCHAKIS 1 Natural HistoryMuseum of Crete,University of Crete,PO. Box2208, Heraklion71409, Crete,Greece

KEYWORDS: Eurasian Griffon;Gyps fulvus;pellet analysis; Europe (Arroyo 1994). The speciesis distributed mainly diet;,Crete. in countries bordering the Mediterranean basin and feeds primarily on livestock carrion (Cramp and Sim- Between a quarter and half of the global range of the mons 1980, Don•tzar 1993). In Crete, the griffon's feed- EurasianGriffon (Gypsfulvus) population occurswithin ing ecology may be more closelyrelated to pastoralism than anywhere else in Europe. Paleontological findings i Email address:[email protected] indicate that all autochthonous-mammalspecies (apart