The Effects of Hunting on Survival Rates of American Black Ducks

Abstract

Using data from 10 preseason and 10 winter major reference areas from 1950-83, we tested hypotheses regarding the effects of hunting on the survival and recovery rates of the American black duck (Anas rubripes). Although our estimates of the proportion of total annual mortality due to hunting are low (35% for ad and 45% for young) compared to Blandin's (1982) estimates, mean mortality and kill rates have increased since 1982. When hunting regulations were liberalized, recovery rates increased and survival rates decreased in males whereas only recovery rates increased in females. Changes in hunting regulations appeared to affect survival rates of adult males and young American black ducks. J. WILDL. MANAGE. 52(2):214-226 The decline of the American black duck is attributed to habitat change and loss (Heusmann 1974, Laperle 1974, Dennis et al. 1985), hybridization with the mallard (A. platyrhynchos) (Heusmann 1974, Johnsgard and DiSilvestro 1976, Ankney et al. 1986), and over-hunting (Geis et al. 1971, Grandy 1983). Although all 3 factors are important, recent evidence for the black duck (Blandin 1982) and the closely related mallard (Rogers et al. 1979, Nichols and Hines 1983, Burnham and Anderson 1984, Burnham et al. 1984) suggests that hunting may not adversely affect survival, and hence, population size. Further, Krementz et al. (1987) have shown that black ducks generally have constant survival rates and time-specific recovery rates; these conditions suggest that compensatory mortality occurs in black duck populations (Anderson and Burnham 1976). 'Present address: U.S. Fish and Wildlife Service, Patuxent Wildlife Research Center, Laurel, MD 20708. 2 Present address: Georgia Cooperative Fish and Wildlife Research Unit, School of Forest Resources, University of Georgia, Athens, GA 30602. This content downloaded from 157.55.39.96 on Fri, 13 Jan 2017 18:13:25 UTC All use subject to http://about.jstor.org/terms J. Wildl. Manage. 52(2):1988 EFFECTS OF HUNTING * Krementz et al. 215 We report on the effects of changes in hunting regulations on the survival and recovery rates of the black duck, and compare our findings to those of similar studies of black ducks and mallards. We believe that our analyses complement and augment the previous analyses of black ducks by Blandin (1982) because our statistical tests used to analyze the question of compensatory mortality are preferable because they include model comparisons and tests with greater power, and our data sets are larger by 6 years (197883). We acknowledge the cooperation and assistance of all State, Provincial, and Federal agencies that participated in the banding efforts. D. R. Anderson, G. M. Haramis, and J. D. Nichols provided helpful comments on earlier drafts of the manuscript.