WHY ARE NUMBERS OF MALLARDS (ANAS PLATYRHYNCHOS) DECLINING IN THE NORTHEASTERN UNITED STATES? THE POSSIBLE ROLE OF REDUCTION IN WINTER FEEDING SITES

摘要

Breeding populations of Mallards (Anas platyrhychos) have declined 38% in the northeastern United States over the past 17 years. One reason for this may be the reduction of a unique wintering habitat, artificial feeding sites. I hypothesize that artificial feeding sites improved over-winter survival and pre-breeding body condition of Mallards and were utilized by a sufficiently large proportion of the northeastern Atlantic flyway population to improve the population's average annual survival and/or fecundity, thereby impacting population dynamics. In Massachusetts, the number of artificial sites where people fed Mallards declined 44% since 1999. Other states do not conduct surveys of feeding sites, but Christmas Bird Counts provide additional data on populations of wintering Mallards. A sampling of urban centered count circles from northeastern states reveal a 48% decline in numbers of Mallards between 1993 counts and those in 2013.