280 SHORT COMMUNICATIONS VOL. 31, NO. 3 j RaptorRes. 31 (3):280-282 ¸ 1997 The Raptor ResearchFoundation, Inc.

THE SUMMERDIET OF THE LITTLE (ATHENENOCTUA) ON THE ISLAND OF ASTIPALAIA(DODECANESE, GREECE)

FRANCESCO M. ANGELICI AND LEONARDO EATELLA Dipartimentodi BiologiaAnimale e dell'Uomo,Universitd di Roma "La Sapienza," viale dell'Universitd32, 1-00185Roma, Italy

LUCA LUISELLI Dipartimentodi BiologiaAnimale e dell'Uomo, Universitddi Roma "La Sapienza,"via A. Borelli50, 1-00161Roma, Italy

FRANCESCO RIGA Istituto Nazionale della Fauna Selvatica, via Ca' Fornacetta 9, 1-40064 Ozzanodell•milia (Bologna),Italy

KEY WORDS: noctua; Little Owl; diet;,Dodecanese, alba).We recentlyreported the first recordsof Barn Greece. on the island (Angelici et al. 1992). Owl pelletswere collectedin abandonedbuildings and at Widespreadand easyto studytaxa are ideal modelsfor a few rocky sites.The collectedmaterial was identified in the laboratory.Small and reptileswere identified analysesof life-historydivergence, because they permit by skulland mandibularremains, and arthropodsby chitin- comparisonsthat are not confoundedby genetically-cod- ous exoskeletonremains. We counted,in the most parsi- ed divergencein other morphological,behavioral and moniousway possible, the frequencyof occurrenceof each ecologicaltraits (Luiselli et al. 1996a, 1996b). The prob- prey speciesin the diet. Although it was not possibleto lem, however,is to find specieswhose life history traits identify Crociduraremains to specieslevel, we assumedthey have been adequately studied in different portions of all belonged to C. suaveolens,a species widespread in the their range. In general, Palearcticowls have a great deal Dodecanese islands (Niethammer 1989). of potential in this area becauseseveral aspects of their Statisticalanalyses were performed by a STATISTICA biology such as food habits have been studied in detail (version 4.5, 1993) for WindowsPC package,with a set at 5%. All data were checkedfor homoscedasticitybefore (Herrera and Hiraldo 1976,Cramp 1985). The exception statisticalanalyses and normalizedif necessary.If thispro- to this is the Mediterranean Islands,especially islands in cedure also failed in obtaining a normal distribution, the Aegean and EastMediterranean Seas,where virtually nonparametric testswere used. Dietary diversitywas as- nothing is known concerningthe food habitsof owls(Ut- sessedby applying Simpson's(1949) and Levins' (1968) tendtrfer 1952, Niethammer 1989). In particular, the formulas to the numerical frequency of occurrence of diet of the Little Owl (Athene noctua) is little known. the variousprey typesin the pellets.

There are some dietary data availablefor islandsin the RESULTS western Mediterranean (Contoli et al. 1988, Lo Verde and Massa1988) but nothing is known about what Little We collecteda totalof 33 completeand an tindetermined Owls eat in the Aegean and East Mediterranean Seas. number of incompleteLittle Owl pellets,containing 1068 In the present paper, we report detailed information prey remains.Excluding the incompletepellets from the on the summer diet of the Little Owl from a Mediterra- analysis,the mean numberof preyper pelletwas 23.3. Little nean island of Dodecanese, Greece. owlspreyed on bothvertebrates (0.56% of the totalnumber of preyeaten) and invertebrates(99.44%) (Table 1). Con- STUDY AREA AND METHODS tingency-tableanalysis showed that Little Owlsfed on inver- Data were collected in late June 1990 on Astipalaia, tebratessignificantly more frequentlythan on vertebrates an island of Dodecanese, Greece (36ø30'-36ø36'N, (X"= 1044.135,df = 1, P < 0.00000001).All invertebrates 26ø14'-26ø30'E,Fig. 1). The island is mainly mountain- eatenwere insects, and mostof themwere (Forficu/a ous (highest elevation, 506 m) with calcareoussoils on lurida) which accountedfor over 70% of the total number the eastern and exterior western sides, and arenaceous of prey itemsingested. Little Owlspreyed significantly more and schistoussoils in the remainingparts. The vegetation is poor, and characterizedby chaparralwith spinyshrubs, often on earwigsthan on all the other preycategories com- ohve-groves,orchards, vineyards and cereal growings.De- bined (X"= 251.24, df = 1, P < 0.000000001). Moreover, tailed faunistic studiesfor Astipalaia have already been the meannumber of earwigsper pelletwas statistically high- done (Angelici et al. 1990, 1992). The islandis inhabited er than that of any other prey typein the diet (paired t, in by two speciesof owls,the Little Owl and Barn Owl (Tyt0 all casesP < 0.00001). Beetles(belonging mainly to the SEPTEMBER 1997 SHORT COMMUNICATIONS 281

0 ! 2 3 4 5 Km

Figure 1. Location of AstipalaiaIsland (Dodecanese,Greece). Symbols:black triangles= high points in elevation; black circles = villagesor towns. familyTenebrionidae) were also frequently eaten (18.16% ysisof prey remainscollected over an entire year would of the total number of prey items eaten). Some antswere showa largerproportion of smallmammals in the diet. We eaten, all of them winged forms. Little Owlspreyed occa- were surprisedthat we did not find remains of murids of sionallyalso on smallvertebrates (lizards, and shrews). the genusMus in the Little Owl diet. These small-sizedro- Dietary diversitywas relatively low either usingLevins' dents(on average17 g in mass)are the mostcommon small index (L = 0.094) or Simpson'sindex (B = 1.751). in Astipalaia(Angelici et al. 1992) and are fre- quentprey species for Little Owlselsewhere (Arias 1994). It DISCUSSION is likelythat Little Owlson Astipalaiabecome more depen- Our data show the summer diet of Astipalaia Little dent on murids later in the season when insects are not as Owls consistsalmost entirely of insects.This finding is abundant (Zerunian et al. 1982). consistentwith Mikkola's (1983) suggestionthat the pro- portion of insectsin the diet of the Little Owl increases RESUMEN.--Loscostumbres de comida del Bfiho (Athenenoc- from the central European regionsto the Mediterranean tua) fue estudiadodurante el veranoen la Isla de Astipalaia, regions due to the lower availabilityof microfine rodents una isla firida en Dodecanese,Grecia donde la ecologiade in the Mediterranean. An apparent exception has been este especiestodavia esta completamente sin conocer.Un shownin Sicily,where Microtussavii is widespreadand is total de 1068 pedazosde presafueron colectados.La dieta frequently preyed upon (16.4% of the total number of de bfiho consistecasi totalmente de insectos,especialmente prey items) by Little Owls (Lo Verde and Massa1988). tijeretas(Forficula lurida). Escarabajos y hormigas con halas tambi6n fueron frecuentemente comidas. Vertebrados casi Our data collection was restricted to the summer season so it is not surprisingthat Little Owlswould be eatinglarge nuncafueron cazados y muypocos ratones chicos del genio numbersof insectslike earwigswhich were readily available. Mus,que estabanmuy abundante en loslabores, casi nunca fueron cazados. Earwigshave been cited as importantprey for Little Owls [Traducci6n de Rafil De La Garza, Jr ] in other areas,including Denmark (Cramp 1985). The Lit- tie Owl diet on Astipalaiais probablygreatly affected by ACKNOWLEDGMENTS seasonalfluctuations in the availabilityof varioustypes of We thank J. Angelopoulos (Athens) for helpful field prey (Cramp1985, Arias 1994). Therefore we feel that anal- assistance,and C. Marti and RJ. Clark for the helpful 282 SHORT COMMUNICATIONS VOL. 31, NO. 3

Table 1. Summer diet of the Little Owl on Astipalaia AreAS,J.M. 1994. Nota sobre alimentacion de mochuelo Island (Dodecanese, Greece). (Athenenoctua L., Aves: Strigiformes). Do•ana, Acta Vertebrata 21:183-185.

PREY TYPE N % N CONTOLI, L., g. ALOISE AND M.G. FILIPPUCCI. 1988. Sulla diversificazionetrofica di Barbagianni Tytoalba e Civ- Vertebrata etta Athenenoctua in rapporto al livello diagnostico Reptilia delle prede. Avocetta12:21-30. Podarcis erhardii 3 0.28 CRAM?, S. [ED.]. 1985. The birds of the western Palearc- Aves tic, Vol. IV. Oxford Univ. Press, Oxford, UI• Passer domesticus 1 0.09 HERRERA,C.M. AND F. HIRALDO. 1976. Food-niche tro- Mammalia phic relationshipsamong European owls.Ornis Scand. Croddurasp. 2 0.19 7:29-41. Arthropoda LEVINS,R. 1968. Evolution in changingenvironments. Insecta Princeton Univ. Press,Princeton, NJ U.S.A. Dermaptera Lo VERDE, G. AND B. MASSA. 1988. Abitudini alimentari Forficulalurida 793 74.25 della civetta (Athene noctua) in Sicilia. Naturalista sidl. Orthoptera 12 (suppl.):145-149. Tettigonidae 42 3.93 LUISELLI, L., M. CAPULA AND R. SHINE. 1996a. Food hab- Coleoptera its, growth rates and reproductivebiology of grass Tenebrionidae 94 8.80 snakesNatfix natfix (Colubridae) in the Italian Alps. Curculionidae 9 0.84 J. Zool.(Lond.) 240: in press. Cerambicidae 7 0.66 --, -- AND -- 1996b. Reproductiveout- Scarabeoidae 1 0.09 put, costsof reproduction and ecologyof the smooth Carabidae 44 4.12 snake (Coronellaaustriaca) in the easternItalian Alps. undetermined 39 3.65 Oecologia106:100-110. MIKKOLA,H. 1983. Owls of Europe. T. & A.D. Poyser, Formicidae 33 3.09 Calton, U.K. NIETHAMMER,J. 1989. Gew611inhalte der Schleiereule (Tyto alba) von Kos und aus Sfidwestanatolien.Bonn. comments on the manuscript. This paper is the contri- Zool. Beitr. 40:1-9. bution No. 226 of the "Ricerche zoologichedelle Univ- ers•t• di Roma nel vicino Oriente." SIMPSON,E.H. 1949. Measurement of diversity.Nature 163:688. LITERATURE CITED UTTENDORFER,O. 1952. Neue Ergebnissefiber die Er- ANGELICI, F.M., M. C•PutA )•ND F. RIGA. 1990. Notes on n/ihrung der Greifv6gel und Eulen. Eugen Umer, the herpetofauna of Astipalaia island (Dodecanese, Stuttgart, Germany. Greece). Brit. Herp. Soc.Bull. 34:31-33. ZERUNIAN,S., g. FRANZINIAND L. SCISCIONE.1982. Little , F. PINCHERA AND F. RIGA. 1992. First record of Owls and their prey in a Mediterranean habitat. Boll. Crocidurasp. and Mus domesticusand notes on the Zool. 49:195-206. mammals of Astipalaia Island (Dodecanese,Greece). Mammalia 56:159-161. Received23 April 1996, accepted25 April 1997