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American Ornithological Society

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In many avian species, females do not nest the first year they attain sexual maturity. I examined the benefits and costs of delayed nesting in a nonmigratory population of Canada Geese (Branta canadensis) in New Haven County, Connecticut, from 1984 through 2008. I individually marked 381 female goslings and monitored them throughout their lives. Eighty-seven females were recruited into the local breeding population; 16 of these started nesting when 1 or 2 years old (young nesters), and 71 started nesting when 3 to 9 years old (delayed nesters). During their first reproductive effort, young nesters and delayed nesters produced similar-sized clutches but young nesters produced fewer hatchlings or fledglings. Young nesters died sooner than delayed nesters, but the two groups were similar in number of years of life following first nesting effort, number of nesting years during life span, and total lifetime production of eggs, hatchlings, and fledglings. Both young nesters and delayed nesters had similar values of λ(m), which is an integrated measure of an individual's propensity fitness. Young nesters weighed more at fledging than delayed nesters, which suggests that larger and healthier females were more likely to become young nesters. Competition among Canada Geese for safe nesting sites on islands was keen in the study area. This may have contributed to the prevalence of delayed nesting because geese that were unable to secure a safe nesting site may have delayed nesting until the following year.

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