Nesting success of ducks on the central Yukon Flats, Alaska

Nesting success was studied at Canvasback Lake and Mallard Lake on the Yukon Flats in interior Alaska in 1989–1991. Simple estimates of nesting success were computed using two techniques that assume a constant daily survival rate (DSR). Maximum-likelihood estimates of nesting success for all ducks, assuming constant DSR, ranged among years and sites from near zero to 12%. However, DSRs were not constant but increased with nest age and initiation date (R² = 0.42, P = 0.0001). Nesting success was near zero for nests initiated 1–10 May and increased to 100% for nests initiated after 30 June. Therefore, species nesting in early to mid season, such as Mallard (Anas platyrhynchos), Northern Pintail (A. acuta), and Northern Shoveler (A. clypeata), had lower success than later nesting species such as Green-winged Teal (A. crecca) and Lesser Scaup (Aythya affinis). In 1990 and 1991, combined nesting success of all species, allowing for variation in DSR with nest initiation date and age of nest, was 12.50%.