The effects of weather, group size and type of nest on the timing of egg-laying in the Southern Ground-hornbill Bucorvus leadbeateri

Autor: P. A. R. Hockey, Kate F. Carstens, Rob M. Little, Reshma Kassanjee, Peter G. Ryan
Rok vydání: 2019
Předmět:
Zdroj: Journal of Ornithology. 160:633-640
ISSN: 2193-7206
2193-7192
DOI: 10.1007/s10336-019-01654-x
Popis: The timing of breeding in birds has important consequences if food availability varies seasonally. Optimal timing of the most energetically demanding stages of breeding to coincide with peaks in food availability can increase breeding success. Early breeding may be challenging for females producing eggs, but generally birds initiating egg-laying early in the breeding season are more likely to succeed. Initiating egg-laying later may be less costly to females, but raising offspring after the peak in food availability becomes challenging. Balancing these costs and benefits is important for the cooperative breeding Southern Ground-hornbill Bucorvus leadbeateri (hereafter ‘Ground-hornbill’), which typically produces only a single clutch of two eggs and fledges a single chick per breeding season. A previous study found that Ground-hornbill groups that lay early in the breeding season are more likely to fledge a chick than later-breeding groups. We investigated factors associated with the timing of breeding such as group size, the type of nest used, rainfall and temperature in a study site supplemented with nest boxes. Ground-hornbills laid eggs from 9 September to 14 November and the average number of days between the first and the last laying date in a season was 48 ± 32 days (range 10–101 days). Larger groups, particularly those using natural nests compared to those using nest boxes, laid later than smaller groups. Egg-laying was delayed under hot, dry spring conditions and laying dates were earlier following above-average spring rainfall.
Databáze: OpenAIRE
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