Low mate fidelity and return rates are common in many migratory bird species. These low rates are likely due to high mortality during migration, making it impossible for between-year mate reunion to occur. Historically, the majority of return rate studies focused on long-distance migrants. We chose to study Eastern Bluebirds (Sialia sialis), a partially migratory and socially monogamous thrush, to better understand how variation in migration affects the evolution of breeding systems and mate choice. We monitored 59 pairs of Eastern Bluebirds across 4 breeding seasons to determine their return and reunion rates. We also examined the relationship between nest success and mate fidelity. Our data indicate that Eastern Bluebirds have high return and reunion rates. Many of the bluebirds that mated together in previous breeding seasons appear to not only reunite the next year, but they also return to the same territory and nesting cavity. Our results differ from previous findings on Eastern Bluebirds and stress the importance of replication in ecology and ornithology.
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10 October 2019
Migratory return rates and breeding fidelity in Eastern Bluebirds (Sialia sialis)
Derek A. Coss,
Kevin E. Omland,
Evangeline M. Rose
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breeding fidelity
divorce
Eastern Bluebird
partial migrants
return rates