|Title||Breeding biology of House Sparrows in northern lower Michigan|
|Publication Type||Journal Article|
|Year of Publication||1994|
|Journal||The Wilson Bulletin|
The breeding biology of the House Sparrow (Passer domesticus) in northern lower Michigan was monitored during the summers of 1986-1991 and the results compared to those obtained in other North American studies. Individuals are multi-brooded with most females laying two or three clutches per year. Overall mean clutch size for the periods of observations was 4.96, and declined as the season progressed. Hatching was asynchronous and indicated that incubation began between the laying of the antepenultimate and penultimate eggs. A strong, positive correlation of mean clutch size with latitude was noted. Incubation period, nestling period, hatching success, fledging success and overall nesting success in Michigan were similar to those found in other North American studies. No latitudinal trends were detected in any of these reproductive characteristics. In a comparison of the timing of the initiation of first and second clutches in North America, however, a strong latitudinal trend was observed, suggesting a retardation of approximately two days in the timing of breeding for each 1 deg. of latitude poleward.