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Providing evidence to improve practice

Individual study: Effect of brown-headed cowbird Molothrus ater control on nesting success of Kirtland's warbler Dendroica kirtlandii on the Lower Peninsula, Michigan, USA

Published source details

Kelly S.T. & DeCapita M.E. (1982) Cowbird control and its effect on Kirtland's warbler reproductive success. Wilson Bulletin, 94, 363-365

This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.

Remove/control adult brood parasites Bird Conservation

A before-and-after study in pine forests in Michigan, USA (Kelly & DeCapita 1982) found that the population of Kirtland’s warbler Dendroica kirtlandii did not significantly increase during 1972-81 when a total of 33,536 brown-headed cowbirds Molothrus ater (a brood parasite) were removed, compared to 1931-71, when no control was in place (average population of 207 individuals during 1975-81 vs. 201 for 1931-71). Population size remained similar despite parasitism rates being significantly lower and warbler productivity being significantly higher during the period with cowbird control (3.4% of nests parasitised and 2.8 chicks/nest fledged with cowbird control, number of nests not provided vs. 59% and less than 1 chick/nest fledged before control, 91 nests examined).