CONDITION AND VULNERABILITY TO HUNTING AMONG MALLARDS STAGING AT LAKE ST-CLAIR, ONTARIO

A basic assumption of band-recovery analysis is that recovered samples are representative of the banded population. This assumption may be violated if individuals in poor body condition are disproportionately vulnerable to hunting. Thus, we used body mass and band-recovery data from 1,412 mallards (Anas platyrhynchos) trapped at Lake St. Clair, Ontario, during August-September of 1989 and 1990 to test the hypothesis that individuals in relatively poor condition before the hunting season subsequently are at a disproportionately high risk of being shot. Supporting this hypothesis, binary regression analysis revealed negative relationships (P less-than-or-equal-to 0.05) between preseason condition (body mass corrected for structural size) and direct recovery probability in 3 of 8 separate analyses (by year, sex, and age), and overall. Our data support the position that condition biases may be widespread in hunter-shot samples of waterfowl, indicating a need for caution when using band-recovery data to estimate hunting mortality and other recovery-based parameters.