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A field test for differences in condition among trapped and shot mallards

Journal of Wildlife Management

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Abstract

We tested predictions from the condition bias hypothesis (Weatherland and Greenwood 1981) regarding the effects of sampling methods of 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.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
A field test for differences in condition among trapped and shot mallards
Series title:
Journal of Wildlife Management
Volume
52
Issue:
2
Year Published:
1988
Language:
English
Contributing office(s):
Patuxent Wildlife Research Center
Description:
227-232
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Journal of Wildlife Management
First page:
227
Last page:
232
Number of Pages:
6