Patterns of roost site selection and use by Southern Ground-Hornbills in north-eastern South Africa

Abstract

Different habitats may be used for the needs of various aspects of an animal’s life. Southern Ground-Hornbill Bucorvus leadbeateri groups announce their presence within year-round territories by calling at dawn from their overnight roost sites. Knowledge on ground-hornbill roosting habits is limited. Groups roost in large trees, apparently close to where they end up after daily foraging. We investigated patterns of roost site selection and use for four Southern Ground-Hornbill groups in the Associated Private Nature Reserves, north-eastern South Africa, based on data from GPS-satellite transmitters. The number of roost sites used per month averaged 15.4 ± 4.7 across all groups, indicating little evidence of strong preferences for specific sites. This number was least when groups were breeding, decreasing throughout the early wet season (October–December) and was lowest during the late wet season (January–March) when actively breeding groups frequently roosted close to the nest (54–83% of roosts <1 000 m of the nest). As might be expected, the mean monthly number of nights per roost peaked during the breeding season (December–January). Riparian habitats were preferred for roosting during the breeding season, whereas disturbed areas, as well as Combretumand mopane-dominated habitats were preferred during the dry non-breeding season. Adequate large trees not only for nesting, but also for roosting, particularly in riparian habitats, may therefore be an important and potentially limiting factor for the successful reproduction of Southern Ground-Hornbills.