The effect of blowfly parasitism on nestling eastern bluebird development

Blowfly (Protocalliphora sialia Shannon and Dobroscky (Diptera: Calliphoridae)) parasitism of nestling Eastern Bluebirds (Sialia sialis ) was studied in a series of 325 nest boxes located in western New York. The nests were monitored closely and nestling development recorded. The results of this study do not support the hypothesis that blowfly parasitism is detrimental to bluebird nestling development and survival. There was no difference in mass or the length of wing, tail or tarsus between parasitized and unparasitized nestlings, nor was there any difference in the age of the young when they fledged. Survival to fledging did not appear to be adversely affected by parasitism.