Diet composition and food supply of the Lesser Spotted Eagle Clanga pomarina in the core area of its breeding range

ABSTRACT Capsule Small rodents and amphibians are both important prey items for the Lesser Spotted Eagle Clanga pomarina, and their proportions in the diet depend on their local availability, as well as the degree of involvement of the female in food provisioning to the nestlings, which increases towards the end of the breeding season. Aims To describe the diet composition and aspects of the food supply of the Lesser Spotted Eagle during the nesting period. Methods Cameras were installed at five nests of three pairs of the Lesser Spotted Eagle in eastern Latvia, to collect data on food items brought to the nests. Results Of 3109 identified prey items, small rodents (43.36%) and amphibians (44.81%) were the most important prey groups. The proportion of common (small rodents and amphibians) and uncommon (moles, birds and others) food items differed between nests and years. Among the common food items, the deficiency of small rodents in some years was compensated for by an increase in frogs and vice versa. Male eagles brought 66% of all food items to the nest. Females brought more amphibians and fewer rodents than did males. After hatching, the mean number of food items delivered to the nest was 6.9 per day. The main activity period of food delivery was between the 3rd to 7th hour after sunrise. Conclusion The alternative prey hypothesis explains the diet of the Lesser Spotted Eagle in our study area. Rodents and amphibians are food items of equal importance that can replace each other, depending on their availability. The increasing share of amphibians towards the end of the breeding season was mainly a result of an increasing proportion of prey items brought into the nest by females.