Reproductive ecology of Tibetan Eared Pheasant Crossoptilon harmani in scrub environment, with special reference to the effect of food

Abstract

We studied the nesting ecology of two groups of the endangered Tibetan Eared Pheasants Crossoptilon harmani in scrub environments near Lhasa, Tibet, during 1996 and 1999–2001. One group received artificial food from a nunnery prior to incubation whereas the other fed on natural food. This difference in the birds’ nutritional history allowed us to assess the effects of food on reproduction. Laying occurred between mid‐April and early June, with a peak at the end of April or early May. Eggs were laid around noon. Adult females produced one clutch per year. Clutch size averaged 7.4 eggs (4–11). Incubation lasted 24–25 days. We observed a higher nesting success (67.7%) than reported for other eared pheasants. Provisioning had no significant effect on the timing of clutch initiation or nesting success, and a weak effect on egg size and clutch size (explaining 8.2% and 9.1% of the observed variation, respectively). These results were attributed to the observation that the unprovisioned birds had not experienced local food shortage before laying, despite spending more time feeding and less time resting than the provisioned birds. Nest‐site selection by the pheasants was non‐random with respect to environmental variables. Rock‐cavities with an entrance averaging 0.32 m2 in size and not deeper than 1.5 m were greatly preferred as nest‐sites. The birds were also more likely to place their nests in denser high‐scrub and closer to streams. In the study area, the low availability of both cliff habitats and high‐scrub patches suggested a limitation of sites suitable for nesting, which could be reflected in the between‐year re‐use of nest‐sites (8.9%) and intraspecific nest parasitism (3.8%). Despite the apparent preference for certain nest‐site variables, we found no effect of these on clutch fate, suggesting that the risk of nest predation was random.