Reproductive Ecology of Isabelline Wheatears at the Extreme of Their Altitude Distribution

Abstract

This paper reports the reproductive ecology of the isabelline wheatear Oenanthe isabellina at a high-altitude area (3,430 m.a.s.l.) on the northeastern Tibetan Plateau. Monogamous pairs bred within territories, placing their nests in burrows. Eggs were laid between late April and early June. The species was single brooded at the study site. Clutch size averaged 5.1 eggs. Incubation by the female lasted 13.5 days and nestlings were provisioned by both parents during a period of 18.5 days. At least one young fledged from 81% of nests. Relative to their low-altitude counterparts, the high-altitude wheatears produced fewer, smaller clutches but larger eggs, and had longer incubation and nestling periods, suggesting a life history strategy adapted to harsh environments.