Birds of Indian Subcontinent

Effects of Age on Reproduction in American Coots

Publication Type:Journal Article
Year of Publication:1980
Authors:Crawford, RD
Journal:The Journal of Wildlife Management
Date Published:1980
ISBN Number:0022541X
Keywords:Fulica, Fulica americana, Fulica atra, Rallidae
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.
Short Title:The Journal of Wildlife Management
Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith