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Ornithological Science
Abstract
Abstract
Loss of mature tropical forests to agricultural expansion often creates landscapes with forest fragments embedded within a matrix of human-modified habitats and land uses. Such habitat fragmentation may be detrimental to species with specialized habitat and foraging requirements and their ability to persist in such landscapes may depend on their adaptability to habitat modification. Great Hornbills Buceros bicornis, among the largest birds in Asian tropical rainforests, depend on large trees for nesting and a diverse array of patchily distributed fruiting trees. In the human-modified landscape of the Anamalai Hills, India, we compared the breeding biology and nesting behaviour of Great Hornbills in contiguous rainforest (N=3 nests) and in modified habitat consisting of coffee plantations and rainforest fragments (N=5 nests). The nesting cycle of seven of the eight nests monitored varied between 114 and 130 days. Nest provisioning behaviour was similar in contiguous forest and modified habitat in terms of visitation and food delivery rates, but visitation tended to be higher and food delivery rate lower during the nestling phase than during incubation. As expected, tree density and native food plant diversity were lower in modified habitat than in continuous forest. The diversity of food provisioned was lower in modified habitat with a 57.5% dietary overlap with contiguous forest. Hornbills in the modified habitat of coffee plantations used non-native tree species for nesting and foraging, indicating their adaptability to modified landscapes.
Funding for this work was provided by core grants to NCBS-TIFR by the Department of Atomic Energy, and a program grant from the Tata Trusts. We thank Oriental Bird Club, UK, for funding support and IDEA WILD for providing field equipment. We are grateful to the Tamil Nadu and Kerala Forest Departments for research permission, particularly Pramod G. Krishnan and V. T. Kandasamy. We thank Amitha Bachan and the Western Ghats Hornbill Foundation, Kerala, for sharing information and providing logistical support during our fieldwork. We would like to acknowledge the managers and staff of Tata Coffee Ltd and Parry Agro Industries Ltd at Valparai for local support and permission to work on their estates. Manikaraj, Moorthy, Suresh, and Sathish Kumar provided valuable field assistance. We thank Kavita Isvaran for helpful discussions about data analysis, Aparajita Datta, and M. Ananda Kumar, and other researchers at the NCF research station. We thank the editors and reviewers for helpful suggestions that improved the manuscript.
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