Gatilov A.S., Voronetsky V.I., 2003. Variety of long-eared owls (Asio otus) diet, as index of habitat usefulness // Mobility of students and programmes flexibility in the prospect of the European unification of the training processes in ecology and environmental science. Italian-Russian student forum. Thesis of the forum. Palermo, 23-26 July, 2003
Long-eared owl A.otus rather actively masters anthropogenous landscapes. In this connection it is interesting to observe change of various aspects of ecology of this species, in particular, dynamics of its food objects.
Observation, and also gathering pellets in places of wintering and under the nests, spent in territory Zvenigorod’s Biological stations and in Moscow’s parks allow to receive representation about dynamics of a diet long-eared owls for some period of time
As one would expect a basis of a diet (70-95%) makes ordinary vole M.arvalis-basic object of specialization long-eared owls and the most mass species of a rodent. In pellets also other rodents (Apodemus agrarius, Clethrionomys glareolus, M.oeconomus, for anthropogenous landscapes Rattus norvegicus and Mus musculus) and also, occasionally, insectivorous (Sorecidae) also are submitted. There are remains of birds less often ((Passer spp., Pyrrhula pyrrhula etc.), insects (Coleoptera), finds bats (Myotis spp) and the rests of the higher plants (for example, swallowed pine cone, it is obvious by mistake…) are individual.
Long-term studying of animals remains ratio in pellets and their correlation with real number of animals (catching by Gyro traps and catchpots) and reproduction success of owls (amount hatches in vicinities and number of nestlings in hatch) allow to note the following law: At decreasing number of the basic fodder object (M.arvalis) in adverse year (for example, after epizooty) and annually at the end of winter forces to pass owls to additional sources of a forage and, hence, raises a variety of a food objects spectrum (it is possible even partial respecialization, for example, on Passer spp. at a dairy farm). Thus decrease of reproductive success (smaller number of nesting pairs and smaller number fledglings in hatch) is marked.
So, these observation show interrelation between a variety of a spectrum of food objects and usefulness of conditions for long-eared owls.