STRUCTURE OF AND LONG-TERM FLUCTUATIONS IN THE WINTERING MALLARD (ANAS PLATYRHYNCHOS, ANSERIFORMES, ANATIDAE) POPULATION IN MOSCOW CITY, RUSSIA

摘要

The structure of and long-term fluctuations in the wintering mallard (Anas platyrhynchos) population were studied from 1985 until 2016 in Moscow City. The number of wintering mallards was counted annually on the same day at all ice-free ponds and rivers of Moscow. The total winter population of mallards increased 1.63.3 times compared to the summer one. A long-term increase continued from 1985 (17.2 thousand) to 1990 (27.9 thousand birds). The size was reduced to 7.5 thousand by 1998, remained low until 2002-2003, but grew in 2015 to 29.7 thousand. The freezing season has decreased from 132 to 104.5 days (Z = 3.8, p = 0.0001, n = 32) during the study period. At the same time, the average air temperatures of November and December have increased significantly. We divided the total number of birds into riverine and interurban local groups that were analyzed separately. The size of the interurban group correlates with the duration of the freezing season (r = -0.47, p = 0.006, n = 32), while that of the riverine group with the average (r = 0.41, p = 0.02, n = 32) and minimum (r = 0.54, p = 0.001, n = 32) winter temperatures. The proportion of mallards that inhabit Moscow Zoo changed in the opposite direction compared to the size of the interurban group (r = -0.83, p 0.01, n = 32). The size of the interurban wintering group correlates with purchasing power (r = 0.44, p = 0.012, n = 31) from 1985 until 2015. This latter correlation reflects citizens' growing welfare.