Breeding ecology and fasting tolerance of scaup and other ducks in the boreal forest of Alaska

Abstract

Information on the breeding ecology of boreal forest ducks is lacking, despite management concern for species such as the lesser scaup (Aythya affinis), whose population has declined markedly since the 1980s. The mechanisms impacting population growth of scaup, and which component of their population dynamics is most affected, are unknown. Previous investigators hypothesized that food deprivation in the spring may reduce breeding success. My objectives were to: 1) examine reproductive parameters of lesser scaup and other ducks on the Yukon Flats in interior Alaska, and 2) measure the tolerance of captive scaup to fasting, in comparison to sympatric Northern shovelers (Anas clypeata) and American wigeon (Anas americana). Although breeding probability of paired females was assumed to be 1.0, the breeding probability of paired female scaup was between 0.12 (SE = 0.05, n=67) to 0.68 (SE = 0.08, n=37), and was positively related to body mass. These results suggest that managers may overestimate the productivity of boreal ducks using traditional survey methods. In addition, captive female scaup completely recovered from a loss of 11% body mass in only four days, suggesting that mass loss can be rapidly reversed, and may be able to obtain the body condition required for reproduction, if food supplies are adequate.