Chronic Low Reproductive Success in the Colonial Tricolored Blackbird from 2006-2011

This publication by U.C. Davis ecologist Bob Meese, which appeared in the journal Western Birds in summer, 2013, summarizes the results of 6 years of field work designed to evaluate the role of insect abundance on tricolored blackbird reproductive success. A total of 47 colonies was studied and relative insect abundance and reproductive success at each was estimated. In only rare instances was reproductive success estimated to be 1 young/nest or greater, and in each case higher reproductive success was correlated with unusually high insect abundance in foraging habitats surrounding colonies. Tricolor reproduction appears to be food-limited and few locations in the Central Valley appear to have the abundance of insects necessary to support reproduction by a colonial insectivorous bird species.