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Effects of Age on Reproduction in American Coots

Richard D. Crawford
The Journal of Wildlife Management
Vol. 44, No. 1 (Jan., 1980), pp. 183-189
Published by: Wiley on behalf of the Wildlife Society
DOI: 10.2307/3808364
Stable URL: http://www.jstor.org/stable/3808364
Page Count: 7
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Effects of Age on Reproduction in American Coots
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Abstract

Relationships between age and breeding biology of American coots (Fulica americana) were studied during 1972-74 in northwestern Iowa. Coots 3 years old and older began nesting about the same date, whereas younger birds nested later within a season. Clutch size increased with age, but only 1- and 2-year-old birds showed seasonal and annual variations in mean clutch size. One- and 2-year-old coots hatched proportionally fewer eggs within a clutch than did older birds. Yearling coots laid smaller eggs and fledged young of lighter weight than did older birds. Fledging success increased with age. Estimated figures from 1 study area indicated that of 471 adults, 57% were 1 year old, 25% were 2 years old, 14% were 3 years old, and 4% were 4 years old or older. Fifty-eight percent of the yearlings nested, and 96% of the 2-year-old coots and all older birds did so.

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