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j. RaptorRes. 37(3):256-258 ¸ 2003 The Raptor ResearchFoundation, Inc.

DIET OF THREE SYMPATRIC OWLS IN STEPPE HABITATS OF EASTERN KAZAKHSTAN

JOANNAVARRO, Jos• ANTONIOSXNCHEZ-ZAPATA, 1 MARTINA CARRETE, AND FRANCISCO BOTELLA Area deEcologfa, Departamento de Biologia Aplicada, Universidad Miguel HernAndez, Ctra Benielkm 3.2, Orihuela,Alicante, Spain

ANDREI GAVRILOV AND SERGEI SKLYARENKO Instituteof Zoology,Ahademgorodoh, 480060 Almaty,Kazahhstan

jos• ANTONIO DONXZAR,OLGA CEBALLOS, AND FERNANDOHIRALDO Departmentof AppliedBiology, Estaci•n Bio•gica Dohana, CSIC,Pabelldn del Perd, Avda. Matra Luisas/n, 41013 Sevilla,Spain

KEYWORDS: Eurasian Eagle-Owl;Bubo bubo; Little Owl; remote steppe habitats have been little studied and their Athene noctua;Long-eared Owl; Asio otus;Asia; diet;, steppe breeding raptor communities resemblethose of Mediter- habitatsß ranean Europe.

We studied the diet and food-niche overlap of three STUDY AREA AND METHODS sympatricowls, the Eurasian Eagle-Owl (Bubotmbo), the The studywas conducted between 12 and 28June 1999 Long-eared Owl (Asio otus) and the Little Owl (Athene in eastern Kazakhstan in central Asia. The climate is con- noctua),during the breeding seasonin semiarid steppe tinental, with very cold winters (when temperatures re- habitats of eastern Kazakhstanand compared their food main under 0øC for months), and warm summers. Such habits with other localities in the western Paleartic. These conditions can also be considered as arid or semiarid with annual rainfall <300 mm. Extreme temperatures and rainfall limit the growthof tree species(Walter 1981) Correspondingauthor's e-mail address:[email protected] and the landscapeis dominatedby steppeand semidesert SEPTEMBER 2003 SHORT COMMUNICATIONS 257

Table 1. Number and percent occurrencein the diet of three owl speciesduring the breeding seasonin eastern Kazakhstan.N = number of prey.

EURASIAN EAGLE-OWL LONG-EARED OWL LITTLE OWL

PREY ITEMS N PERCENT N PERCENT N PERCENT

Birds 54 17.3 2 2.5 8 4.1 Sturnus roseus 25 8.0 2 2.5 0 0 Falco naumanni 4 1.3 0 0 0 0 Unidentified 25 8.0 0 0 8 4.1 Reptiles 19 6.1 1 1.2 3 1.5 Lacertidae 2 0.6 0 0 1 0.5 Colubridae 9 2.9 1 1.2 0 0 Unidentified 8 2.6 0 0 2 1.0

Mammals 195 62.5 74 91.3 109 55.3 Microtidae 82 26.3 39 48.1 39 19.7 Muridae 12 3.9 27 33.4 8 4.1 Hemiechinus auritus 45 14.4 1 1.2 1 0.5 Sciuridae 39 12.5 6 7.4 8 4.1 Soricidae 1 0.3 0 0 0 0 Unidentified 16 5.1 1 1.2 53 26.9

Invertebrates 44 14.1 4 5.0 77 39.1 Coleoptera 13 4.2 2 2.5 53 26.9 Orthoptera 19 6.1 2 2.5 11 5.6 Unidentified 12 3.8 0 0 13 6.6

Total 312 81 197

plains and hills with herbaceousvegetation and small RESULTS bushes, whereas trees are confined to foothills of large The diet of the eagle-owl included mostly mammals mountains (Tian Shan in the south, Altai and Alatul in the east) or around human settlementsand river valleys. and birds (Table 1). The main prey specieswere voles Pellets were collected in two different habitat typesin (Microtidae) and medium-sizedmammals such as hedge- the studyarea (Sanchez-Zapataet al. 2003): (1) Seminat- hogs (Hemiechinusauritus) and hamsters(Citellus sp., Sc•- ural grasslands.Here the landscapewas dominated by rus sp., Alactagasp., Pygerethmussp.) and RosaceusStar- extensivelivestock use and widespreadcroplands, but vil- lings (Sturnusroseus). Long-eared Owls preyed almost lages are small with <500 inhabitants.There are many exclusivelyupon small rodents such as mice (Muridae) abandoned fields and degraded steppe areas. (2) Dry and voles, whereas Little Owls fed mainly on small ro- steppes.This includes large areas of natural dry steppes dentsand invertebrates,mostly beetles (Coleoptera). The with little or no human presence.Trees are lacking and diversityof the diet of eagle-owls(D = 7.63) and Little the vegetation is dominated by grassesand forbs (Arte- misiaspp., Limoniumspp., Salsolaspp., Ephedraspp., Hal- Owls (D = 5.10) washigher than that of Long-earedOwls oxylonspp.). There are also sparserocky outcrops. (D = 2.85). Food niche overlapwas higher betweeneagle Fresh pellets were collected under perches around and Long-earedOM (O = 0.73), than between Little nestsof the three species.Overall, we analyzed108 pel- OMs and the two other species(O = 0.58 and 0.47, re- lets of the EurasianEagle-Owl collected in nine localities, spectively). 40 pellets of Long-earedOwls collectedin two localities, The diet of the eagle-owlwas more diversein steppe and 107 pellets of Little Owls collectedin tour localities. habitat than that found in Mediterranean countries, All prey items were classifiedinto 15 different categories where the speciesfeeds mainly on rabbits (Oryctolaguseu- (at the level of species,family, or order) included in four niculus), one of the staple food sourcesfor top predators broad classes;birds, reptiles, mammals (Corbet 1978), and invertebrates. Diversity was quantified by means of of Mediterranean ecosystemsin Western Europe (Delibes the Levin'sIndex (D = 1/Z p•2)whereas food nicheover- and Hiraldo 1981). The absence of rabbits and the &- lap was calculated using the MacArthur-Levins'sIndex urnal habits of similar medium-sized rodents in steppe modifiedby Pianka (O,7 = Z pamPailk/(•ph,9 • ph72)(Marti habitats of Central Asia may be responsible tbr this dif- 1987, Krebs 1989). ference. As a consequence,small rodents, hedgehogs, 258 SHORT COMMUNICATIONS VOL. 37, NO. 3 and birds (including raptors) play an important role in in the Iberian Mediterranean ecosystemsin western the diet, similar to that found in other smniarid Mediter- Europe. In K. Myers and C.D. McInnes lEDs.], Pro- ranean habitatswhen rabbits are scarce(Jaksia and Marti ceedings of the World Lagomoph Conference, 1984, Serrano 2000, Martinez and Zuberogoitia 2001) Guelph, Canada. and other semiarid or lower-latitude Nearctic biomes DONAZAR,J.A., F. HIRALDO,M. DELIBES,AND R.R. ESTRE- (Donazar et al. 1989, Marchesi et al. 2002). [I•. 1989. Comparative food habits of the Eagle Owl Long-eared Owls had a similar diet to that reported for (Bubobubo) and the Great-horned Owl (Bubovir•nia- other populations in the Western Palearctic,with voles nus) in six Nearcftc biomes. Ornis, Scand.30:398-306. and mice as the main prey species,with the exception of G•c•& A. AND E CEaVER& 2001. Notas sobre la variaci6n a few localities in Mediterranean and suburban habitats estacionaly geogr•tficade la dieta del bfiho chico. Ar- where birds may also play an important role in the diet deola 48:54-80. (Garcia and Cervera 2001). HEaP,•P,^, C.M. AND F. H•P,•DO. 1976. Food-niche and The diet of the Little Owl was also similar to that de- trophic relationships among European owls. Ornis scribed in the Western Palearctic (Mikkola 1983), al- Scan& 7:29-41. though invertebrateswere more important in Mediter- J)dcsIC,F.M. AND C.D. M•O•TL 1984. Comparative food ranean countries (Mafiez 1983) and rodents were more habits of Bubo owls in Mediterranean-type ecosys- •mportant in temperate-climateareas including cold de- tems. Condor 86:288-296. serts (Herrera and Hiraldo 1976). Our resultspoint out K•Bs, CJ. 1989. Ecologicalmethodology. Harper & Row that despite regional differences in prey communities, Publ., New York, NY U.S.A. owls did not show large intercontinental differences in M•Ez, M. 1983. Espectro alimenticio del Mochelo co- food-niche metrics, as suggestedin previous broader- turin (Athenenoctua) en Espafia.Alytes 1:275-289. scale studies (Marti et al. 1993). MARCHESI, L., F. SERGIO, AND P. PEDmNL 2002. Costs and benefits of breeding in human-altered landscapesfor RESUMEN.--Seestudia la dieta de tres rapacesnocturnas; the Eagle-OwlBubo bubo. Ibis 144:164. el mochuelo (Athene noctua), bfiho chico (Asio otus) y MARThC.D. 1987. Raptorfood habitsstudies. Pages 67- bfiho real (Bubobubo) en h•tbitatsesteparios de Kazasfftn. 80 in B.A. Giron Pendleton, B.A. Millsap, K.W. Cline, Los restosde presasse obtuvieron del an•disisde egagr6- and D.M. Bird lEDs.I, Raptor management tech- pfias recogidasen las proximidadesde los nidos durante niques manual. National Wildlife Federation, Wash- el periodo reproductor. Los invertebrados y micro•na- ington, DC U.S.A. miferos fueron la presa principal de Athenenoctua, mien- , E. KORPI 'lVLgd4J,AND F.M. JAKS•C.1993. Trophic tras que Asiootus pred6 casiexclusivamente sobre micro- structure of raptor communities: a three-continent mamfferos y Bubo bubo present6 una dieta muy comparisonand synthesis.Pages 47-137 in D.M. Pow- &versificada, aunque basadaen avesy mamlferos de me- er [ED.], Current Ornithology, Vol. 10. Plenum Pub- drano tamafio. La dieta de las tres especiesfue m•tssire- lishing Corporation, New York, NY U.S.A. fiat a la observadaen latitudes templadasy desiertosfrios MARTINEZ,J.A. ANDI. ZUBEROGOITIA.2001. The response que a la descrita para ecosistemasmediterr•meos semi•t- of the Eagle Owl (Bubo bubo) to an outbreak of the ridos. rabbit haemorrhagicdesease. J. Ornithol.142:204-211. [Traducci6n de los autores] MmKOIA, H. 1983. OMs of Europe. T. & A.D. Poyser, Berkhamsted, U.K. ACKNOWLEDGMENTS S/•tNCHEZ-ZAPATA,J.A., M. CARProTE,A. G^WILOV,S. We are very grateful to Ana Erailia L6pez and Alicia RENKO,O. CEBALLOS,J.A. DONAZAR,AND F. HmALDO Montesinos for their help with the pellet analyses.The 2003. Land use changes and raptor conservation in Institute of Zoology of Almaty (Kazakhstan) provided valuable help in organizing the ficld work and a refer- steppe habitats of Eastern Kazakhstan.Biol. Conserv ence skull collection. 111:71-77. SERRANO,D. 2000. Relationshipbetween raptors and rab- LITERATURE CITED bits in the diet of eagle owlsin southernEurope: com- COPmET,G.B. 1978. The mammals of the palearctic re- petition removal or food stress.J. RaptorRes. 34:305- gion. A taxonomic review. British Museum. Cornell :310. Univ. Press, London, U.K. WAI,TE•, H. 1981. Los sistemaseco16gicos de los conti- DEEmES,M. •ND F. HW,ALDO. 1981. Thc rabbit as a prey nentes. Omega, Barcelona, Spain.