Umbrella effect of peregrine falcon Falcoperegrinus in nesting period in relation to the community of small rodents

Peregrine falcon is a top predator with an aggressive behavior during protection of the nest. Other relative timid species of birds use this feature of nesting pair of peregrine falcons and build nests at the distance of 20-100 m from the predator's nest. This effect induced by behavior of a nesting pair of peregrine falcon is called the «umbrella» effect. In this paper, we report the results from study according to which we verified this effect in relation to the community of small rodents on the territory of southern shrub tundra on the Yamal peninsula. The experiment was carried out near the five nests of peregrine falcon. At each nest we held a trapping session using the trap line method on the distance of 500 m, 1000 m, 1500 m (control) and directly near the nest. Eventually, we can make the conclusion that near the nest of peregrine falcon, the abundance index of small rodents is higher and decreases with the distance from the predator's nest. High abundance index of small rodents near the nests of peregrine falcon is formed both by adults and juveniles individuals. The effect from aggressive behavior of peregrine falcon during the nest protection is most expressed directly near the nest and up to 500 m.