|Title||Cessation of breeding in the multi-brooded House Sparrow (Passer domesticus)|
|Publication Type||Journal Article|
|Year of Publication||1998|
|Journal||International Studies on Sparrows|
The role of female condition in determining incidence of late-season broods in House Sparrows (Passer domesticus) was evaluated during a six-year study on dairy farms in northern lower Michigan. Female condition declined during the course of both mid-season and late-season broods, but no significant difference was noted in condition between marked females that subsequently initiated late-season broods and those that did not. Females initiating late-season broods had an average mid-season clutch size 0.6 egg larger than females failing to initiate late-season broods. Two-year-old and older females were more likely to have late-season broods than first-year birds and birds of unknown age. Brood manipulation studies with marked females were performed during three years to test whether the demands of feeding enlarged mid-season broods had an effect on the incidence of late-season broods. Fledging success of enlarged mid-season broods was no different from that in control mid-season broods, but females rearing enlarged mid-season broods were less likely to initiate late-season broods. I propose that the proximate mechanisms controlling the intitation of breeding and determination of clutch size in the House Sparrow are largely responsible for cessation of breeding in the species.