Spring migration of waterfowl and wading birds in the Western Transbaikalia

In the recent decades the composition of ornithofauna of azonal ecosystems in the Western Transbaikalia is constantly changing, so it needs in periodical revision. The spring migrations of waterfowl and wading birds were studied during the hike route and automobile surveys of reservoirs in combination with stationary and short-term observations in the period from 1999 through nowadays. The routes went along the Borgoisky, Orongoisky and Barguzinsky basins, the lakes of the Eravno-Khorginsky system. The waterfowl and wading birds were represented by 75 species of six orders: loon-like, sheldrake-like, storklike, goose-like, crane-like, plover-like ones. The dynamics of waterfowl and wading birds’ migration in the Western Transbaikalia has a consequent periodicity depending on natural periods of a year (by Filonov, 1978): 1) the flight begins from the second half of March and goes on through the second decade of April (pre-spring); 2) from the third decade of April through the first decade of June the mass flights of birds go on (spring), reaching its peak to the mid of May; 3) the spring migration finishes from the second decade of June through the end of the third decade of June (pre-summer). The diversity of the waterfowl and wading avifauna at the spring flight in the Western Transbaikalia is conditioned by a great number of flying by birds. The early coming is characteristic for nesting species of the goose-like birds, the later coming - for flying by northern sandpipers. Though the presence of flying by species is of short-term at reservoirs, terms of stay of some species don’t coincide between them and are prolonged in time. On the whole the spring migration of the waterfowl and wading birds has the expressed periodicity and goes on for nearly 2,5 months. The greatest species diversity (49 species) is observed to the mid of May.