Different life strategies of two waterfowl species introduced inMoscow

摘要

In addition to a large group of mallards, Moscow provides breeding and wintering grounds for Ruddy Shelducks (Tadorna ferruginea) and Common Goldeneyes (Bucephala clangula). Both species were introduced there (released in the Zoo) in the 1950s. Ruddy Shelducks started nesting in the city already in 1956, while Goldeneyes only in 1975. The numbers of both species have been increasing since then, but the rate of population growth differed: it was much higher in Ruddy Shelducks, particularly in the last years (from 105 in 1998 to about 400 in 2005). All Ruddy Shelducks winter in the Zoo and breed outside it, nesting in the attics of high-storey buildings and rearing broods on the city ponds. For half a century no birds left the city neither in autumn, nor in spring; the situation may have changed in recent years, though we have no reliable proofs for it.