Breeding-Season Decisions, Renesting, and Annual Fecundity of Female Eastern Meadowlarks (Sturnella Magna) in Southeastern Illinois

Annual fecundity is a demographic parameter that is elemental to population biology, but accurate measures of fecundity are rarely obtained. We used radiotelemetry to follow female Eastern Meadowlarks (Sturnella magna) throughout the 1999-2000 breeding seasons in southeastern Illinois to estimate their annual fecundity and assess if the outcome of initial nesting attempts affected site selection for subsequent nests. Thirty-four females built 52 nests (1.53 ± 0.12 nests female−1), but only 21 females (62%) fledged young. Only 44% of females renested at the study site, and more females (53%) emigrated after successfully fledging young from an initial nest than after failing in their first attempt (21%). Nest-site characteristics were similar between successful and failed nests for both initial and subsequent attempts. Females that failed during first attempts did not change nest characteristics for renests. Given that few females were double-brooded and that unsuccessful females did not persistently renest, annual fecundity for females nesting at the study site was between 1.27 ± 0.38 and 1.36 ± 0.37 female young year−1. On the basis of our fecundity measure, we estimated that annual adult survival of 59–61% was necessary for maintenance of a stable population (λ = 1.0). Failure of most females to attempt to raise two broods suggests that double brooding carries substantial costs for meadowlarks.