Little Owl Athene noctua predation on vertebrates in Italy

Marco Mastrorilli via Carducci 7 Boltiere (BG) ITALY flammeus@libero.it

The diet of the Barn Owl Tyto alba and the Tawny Owl Strix aluco, and the winter diet of the Long-eared Owl Asio otus have been studied in Italy (Benussi,1997, Bon et al.,2001). The diet of the Little Owl Athene noctua has been poorly investigated: few papers have been published and they deal with a small number of areas, mainly in Central and Southern Italy.

This paper is a whole review of the works about the species preyed on by the Little Owl published in Italy between 1900 and 2001.

A considerable percentage of the Little Owl diet consists of invertebrates. Data about the species preyed on lack, the study of arthropods and gastropods being very difficult. In some papers, data also lack about vertebrates: reptiles, amphibians and even chiropters. Locally, vertebrates can cover an high percentage of the diet, seasonal variations poorly investigated so far can occur.

The locally important role of vertebrates and the consequent high amount of biomass they give - has driven me to analyse their occurrence in the alimentation of the Little Owl.

35 papers have been considered, 28 of them report data about vertebrates. The predation on vertebrates occur only in some parts of the country.

The studies have been mainly carried out in Lazio (Central Italy), Campania (Southern Italy) and Sicily (Southern Italy).

The analysis of the literature has shown a marked euriphagy and microphagy. In some conditions, the Little Owl adapts itself, feeding on the species occurring in the places it lives in.

A checklist of the vertebrates preyed on by the Little Owls has been drawn up in order to enable comparisons.

A case of cannibalism have been reported, rests of a juvenile have been discovered in pellets found in Campania (Southern Italy).

The largest bird species are Blackbird Turdus merula and Starling Sturnus vulgaris; the Little Owl diet also includes small and particular species, such as Sand Martin Riparia riparia and Dunnock Prunella modularis.

Many birds preyed on usually frequent urban and suburban areas.

17 micromammal species have been reported, amongst them two moles in two different places (Russo, 1997).

Chiropters are seldom preyed on, other nocturnal raptors show higher percentages of these mammals in their diet.

The predation on reptiles and amphibians by nocturnal raptors has been dealt with (Mastrorilli et al., in press). Lizards (Podarcis ssp) are regularly preyed on by Little Owls, the predation of other reptiles is more occasional. The largest prey turned out to be a Grass Snake Natrix natrix (28 cm. long) seized by daylight, but lost in flight (Mostini, 1998). Predations on anurans are more irregular.

The following list includes the vertebrate species reported by the literature.

Reptilia (5 species)

Tarentola mauritanica / Wall Gecko, Chalcides chalcides / Seps, Podarcis muralis / Common wall lizard, Podarcis sicula / Ruin lizard, Natrix natrix/ European Grass Snake.

Amphibia (2 species)

Hyla arborea / Tree frog, Rana esculenta / Green frog.

Aves (17 species)

Athene noctua / Little Owl, Apus apus / Swift, Riparia riparia/ Sand Martin, Hirundo rustica / Barn Swallow, Delichon urbica/ House Martin, Prunella modularis / Dunnock, Erithacus rubecola / Robin, Phoenicurus ochruros / Black Redstart, Turdus merula / Blackbird, Parus major / Great Tit, Sturnus vulgaris / Starling, Passer domesticus / House sparrow. , Passer Italiae / Italian sparrow, Passer montanus / Tree sparrow, Fringilla coelebs / Chaffinch, Carduelis carduelis / Carduelis chloris/ Greenfinch.

Mammalia (17 species)

Sorex araneus / Commun shrew, Sorex minutus / Pygmy shrew, Neomys anomalus / Miller's water shrew, Suncus etruscus / Pygmy white-toothed shrew, Crocidura leucodon / Bi-coloured white-toothed shrew, Crocidura suavolens / Lesser white-toothed shrew, Talpa europaea / Common mole, Talpa romana / Roman mole, Moscardinus avellanarius /Common dormouse, Clethrionomys glareolus / Bank vole, Arvicola terrestris / Water vole, Microtus savii / Savi's pine vole, Apodemus sylvaticus /Wood mouse, Micromys minutus / Harvest mouse, Rattus norvegicus/ Brown rat, Rattus rattus / Black rat, Mus domesticus /Western house mouse.

References

Benussi E., 1997. Stato delle conoscenze sui rapaci notturni in Italia, 1900 – 1996. Avocetta 21:86

Bon M., Ratti E., Sartor A..,2001. Variazione stagionale della dieta della Civetta Athene noctua (Scopoli,1769) in una localita’ della gronda lagunare veneziana. Boll.Mus. civ.St.nat. Venezia 52:193-212

Mastrorilli M., Gentilli A., Sacchi R., in press. L’importanza dell’erpetofauna nella dieta degli Strigiformi italiani. Pianura, Atti del III Convegno Societas herpetologica Italica

Mostini L., 1998. Comportamenti alimentari di alcune specie ornitiche. Riv. Ital.Ornit. 68: 111-115

Russo D. 1997. Primi dati sulla comunità ornitica dell'area protetta "Torre di mare" (Capaccio-Salerno): aspetti faunistici ed ecologici. Uccelli d'Italia 22:18-25

Acknowledgements

Special thanks to Armando Nappi and Matteo Barattieri.

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