Abstract
Reproductive data of high-altitude blackbirds (Turdus merula maximus) were collected at an alpine environment covered with scrub vegetation in Lhasa mountains, Tibet. The blackbird nests were found from 3,800 to 4,500 m at a breeding density of 0.07 pairs/ha. Egg-laying occurred from early May to late July, with a peak (73.0% of all nesting attempts) between mid-May and mid-June. Most (79.5%) of the nests were sited in six different plant species with Cotoneaster microphyllus being most preferred. A few (20.5%) nests were against rocky walls. Bushes used for nest sites were significantly higher. Compared with lowland blackbirds, montane blackbirds experienced a shorter breeding season (2.5 months), laid smaller clutches (2–4 eggs, averaging 2.86), but larger eggs (mean volume index 16,348), produced only one brood per year, had a slightly shorter incubation period (12–13 days), but a longer nestling period (16–18 days), and enjoyed a higher breeding success (59.0%). In the alpine environment where climate is harsh and food supply poor, the strategy of increased egg size with decreased clutch size suggests that the high-altitude blackbirds improve their breeding success by investing more reproductive energy in fewer offspring in response to the constraints of time and resources. However, the environmental constraints on reproduction result in a low annual reproductive output.
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Acknowledgements
I wish to thank the Buddhists in Xiongse nunnery for accommodation, my student, G.H. Gong, for field assistance, and C.F. Mason of Department of Biological Sciences, University of Essex, for improving the English of the original manuscript. This work was conducted in the Field Research Station for Tibetan Wildlife, jointly administered by Wuhan University and Tibet University. Financial support was provided by National Sciences Foundation of China (Grants 30270216 and 30370241).
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Lu, X. Reproductive ecology of blackbirds (Turdus merula maximus) in a high-altitude location, Tibet. J Ornithol 146, 72–78 (2005). https://doi.org/10.1007/s10336-004-0058-1
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DOI: https://doi.org/10.1007/s10336-004-0058-1