We studied breeding ecology of the American Robin (Turdus migratorius) on the campus of Iowa State University. We estimated nest success, as measured by the Mayfield method, to be 53.6% for the 13-day incubation interval, 77.5% for the 12-day nestling interval, and 41.2% for the entire nesting cycle. Daily survival rates did not differ between small and large clutches, but nests on buildings experienced a much lower success rate (3.2%) than nests placed in trees and shrubs (44.0%). Early season nests placed in trees and shrubs were less successful (37.1 %) than late season nests in trees and shrubs (66.7%) (p < 0.05). Daily survival rates during the nestling period were consistently higher than during the incubation period in all analyses. Predation was the major cause of mortality for eggs, whereas predation and starvation were the major causes of mortality for nestlings.
Bird, Ecology, Mayfield method
