Mate Loss in Winter Affects Reproduction of Mallards

Abstract

Mallards (Anas platyrhynchos) frequently pair during winter, and duck hunting scasons have been extended until the end of January in several southern states in the Mississippi Flyway. Therefore, we simulated dissolution of pair bonds from natural or hunting mortality by removing mates of wild-strain, captive. yearling female mallards in late January 1996 and early February 1997 to test if mate loss in winter would affect subsequent pair formation and reproductive performance. Most (97%) widowed females paired again. Nesting and incubation frequencies, nest-initiation date, days between first and second nests, and egg mass did not differ (P > 0.126) between widowed and control (i.e., no mate loss experienced) females in 1996 and 1997. In 1997, widowed lemales laid 1.91 fewer eggs in first nests (P = 0.014) and 3.75 fewer viable eggs in second nests (P = 0.056). Computer simulations with a mallard productivity model (incorporating default parameters [i.e., average environmental conditions]) indicated that the observed decreased clutch size of first nests. fewer viable eggs in second nests, and these factors combined had potential to decrease recruitment rates of yearling female mallards 9%. 2%, and 20%. Our results indicate that winter mate loss could reduce reproductive performance by yearling female mallards in some years. We suggest cantion regarding extending duck hunting seasons in winter without concurrent evaluations of harvest and demographics of mallard and other duck populations.