鸟类囤食的那篇考古背景

We report on the incidence of male incubation and multiple brooding in Sagebrush Brewer's Sparrows (Spizella breweri breweri) at the northwestern limit of their breeding range in southern British Columbia, 1998–2000, and in central Washington, 1996–1999. Males frequently incubated eggs, accounting for 28% of 329 observations of incubation by known individuals in British Columbia. In Washington, 51% of the males we monitored incubated eggs. Males and females appeared equally able to increase nest temperature. In British Columbia, 17% of females fledged two broods per season, and two females fledged three broods. In Washington, 5% of males fledged two broods per season. Only one previous case of male incubation has been reported in this species and multiple brooding has been poorly documented. These aspects of the breeding biology of other well-studied species may be underestimated without the careful examination of populations of marked individuals.