The oriental white stork Ciconia boyciana feeding in the middle part of the Amur river area, morphometric features of fishes, frogs and water beetles in its food and microhabitats and role of vegetable rubbish in its food

The studies were carried out in 1974-1976 and 1978 in the lower reaches of Bureya River (the southern part of Arkhara district of Amur Region, the Middle Amur River area). In 1978 2768 objects of the Oriental White Stork food were collected. An analysis of these and earlier published data (Винтер, 1978) on the base of 590 food objects has allowed to compile «balanced» spectrum of food of this species chicks (on 3280 forage objects) that has shown that fish dominates in feeding of chicks (74.2 % number of objects and 87.0 % total biomass of food), and among invertebrates - water beetles, molluscs, Orthoptera, Hirudinea and Arachnea (respectively, - 38.7; 19.4; 12.9; 12.9 and 12.9 % records). The content of the pellets characterizes the ratio in the food of large Acridoidea and Coleoptera, but does not reflect the role of vertebrates in food of this species. The pellets contain fish at 112 times less and frogs at 1.6 times less than portions of food. The relative number of insects in pellets is bigger at 38.2 times, and mammals - at 11.7 times bigger than in portions of the stork food (Winter 1991). Comparison of different characteristics of animals, contained in food and those catched in the foraging habitats of stork has shown that Stork а) almost completely avoid minnow, who dominated by number in feeding microhabitats of stork; an avoidance by stork of water beetles is expressed in a lesser extent; b) however the stork prefers the Chinese sleeper and selects only small specimens (the average biomass of which in food is at 7.0 - 7.1 times smaller than in food microhabitats). The latter was recorded for loaches too. The observations at foraging sites and watching through the stork prey have shown that the bird catches the fish by the apical third part of the bill (more often - at 10-12 % of its length from the top), usually - for the base of the tail. About 40 % attempts to keep fish in bill are unsuccessful and storks are forced to intercept prey another time or even two times. The stork food variability is shown, depending on water level in water bodies, together with individual differences in food composition of different pairs and inter-seasonal distinctions of the food base. Anthropogenic impact (fires, sharply destroying hydrological regime of the territory) imitates the dry seasons, stultifying the positive effect of precipitation that regulate the water level in water bodies at the Oriental White Stork habitats. It was established that the regular bringing of vegetable rubbish into the nest by storks in dry weather happened more often than in rainy weather. This is another evidence of the bird behaviour dependence in the middle latitudes on weather (Winter et al. 1999; Винтер, Горлов 2003; Winter, Gorlov 2003; Винтер, Мысленков 2011).