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A Field Test for Differences in Condition among Trapped and Shot Mallards
Kenneth J. Reinecke and Charles W. Shaiffer
The Journal of Wildlife Management
Vol. 52, No. 2 (Apr., 1988), pp. 227-232
Stable URL: http://www.jstor.org/stable/3801226
Page Count: 6
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We tested predictions from the condition bias hypothesis (Weatherhead and Greenwood 1981) regarding the effects of sampling methods on body weights of mallards (Anas platyrhynchos) at White River National Wildlife Refuge (WRNWR), Arkansas, during 24 November-8 December 1985. Body weights of 84 mallards caught with unbaited rocket nets in a natural wetland were used as experimental controls and compared to the body weights of 70 mallards captured with baited rocket nets, 86 mallards captured with baited swim-in traps, and 130 mallards killed by hunters. We found no differences (P > 0.27) in body weight among sampling methods, but body condition (wt/wing length) of the birds killed by hunters was less (P < 0.02) than that of the controls. Power of the test statistics to reject the null hypothesis of equal body weights among sampling methods was >0.75 for differences >50 g. The condition bias hypothesis probably applies to ducks killed by hunters but not to trapping operations when substantial (>20 at 1 time) numbers of birds are captured.
The Journal of Wildlife Management © 1988 Wiley