The birds of Pasvik / E. I. Khlebosolov, O. A. Makarova, O. A. Khlebosolova [et al. ; English transl. Nikita Chernetsov]. - Ryazan : Golosgubernii, 2007. - 175 с. : ил., портр.

They apparently prefer to forage in the areas where m icrorelief, structure o f ground vegetation and spatial distribution o f rodents are optimal for their foraging tech ­ niques. Owls Owls, like some diurnal birds o f prey, mainly feed on mice and voles. However, their important difference is that they rely on their hearing when foraging. D iurnal raptors cannot take small rodents in the forest and other closed habitats because o f trees, scrub, brushwood, snow and other obstacles. For owls this is a m inor prob­ lem. Their auditory system allows them to hear low sounds and locate the position o f the prey with high accuracy. Therefore they can forage under the conditions of low visibility. Mainly nocturnal or twilight activity o f owls is caused by weaker wind and general quiet conditions when foraging by ear becomes possible. On noisy nights the probability of successful hunting considerably decreases, and under strong wind o r rain the owls do not forage (Pukinsky 1977). In Pasvik, the Short-eared Owl, Northern Hawk-Owl and G reat Grey Owl are common. These species have similar diets but use different habitats and utilize spe­ cific hunting techniques. Short-eared Owls prefer open habitats, wetlands, meadows and sedge swamps on the shores o f rivers and lakes, forest fire sites with sparse young forest. They also occur in the mountain tundra (Pukinsky 1977, Semenov-Tian-Shansky & Gilyazov 1991). Their main food is voles. Sometimes Short-eared Owls also take small birds. During hunting, sit-and-wait technique is combined with patrolling. During the daytime and twilight search for food usually occurs in flight, in the darkness the owls sit and wait. Usually the Short-eared Owls take off in the daytime, after a day rest, and start to circle in the hunting range. They regularly hover over a particular site and only after that descend and start searching for prey, flying 3—4 m above the ground. After darkness, another foraging technique is utilised. The owl either sits on a tussock, listening for faint sounds, o r circles above the same area for a long time (Pukinsky 1977, Gorchakov 2004). 89