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Effects of body weight and age on the time and pairing of American black ducks

Auk

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Abstract

I used captive young and adult American Black Ducks (Anas rubripes) during October-February 1984-1985 to test whether body weight and age affected time of pair-bond formation. Eighty ducks were marked individually, and 10 ducks (6 males and 4 females, half of each age class) were assigned to each of 8 experimental pens. Ducks in 4 pens received an ad libitum diet of commercial duck food, and ducks in the other 4 pens received a restricted ration of the same food. During early winter ducks in both groups gained weight, but ducks on the restricted diet gained less than birds on the ad libitum diet; peak winter weight of ducks on the ad libitum diet averaged 22% greater than initial body weight compared with 6.5% for ducks on the restricted diet. In late winter ducks on the restricted diet lost 28.7% of peak winter weight, and ducks on the ad libitum diet lost 19.3%. Weight loss of ducks on the ad libitum diet began before weather conditions became severe and coincided with a reduction in food consumption. This result supports the idea that weight loss of waterfowl in late winter is controlled endogenously. Individuals on the ad libitum diet paired earlier than those on the restricted diet, and pair bonds were stronger. Adults of both sexes paired earlier than young ducks, but differences for females were not significant statistically. Age and energy constraints are factors that can affect intraspecific variation in pairing chronology.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Effects of body weight and age on the time and pairing of American black ducks
Series title:
Auk
Volume
103
Issue:
3
Year Published:
1986
Language:
English
Contributing office(s):
Patuxent Wildlife Research Center
Description:
477-484
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Auk
First page:
477
Last page:
484
Number of Pages:
8