A comparitive study of the breeding behaviour of the Augur Buzzard, Buteo augur, in the two different land-use areas in southern Lake Naivasha, Kenya

摘要

A comparative study of the breeding behaviour of the Augur Buzzard Buteo augur was made in two contrasting areas on the southern side of Lake Naivasha, Kenya. Hell's Gate National Park represented a natural site, and the lake environs an agricultural site. Locations of adult birds and their activity time budget during the breeding cycle were studied from April to October 1995. Factors influencing prey delivery and nestling feeding rates, and intra-/inter-specific interactions were given special attention. Augur Buzzard pairs in the lake environs spent more time caring for chicks than their counterparts in Hell's Gate. This was apparent in the increased maternal care and paternal foraging which resulted in larger broods and more prey deliveries to nests respectively. Prey and biomass delivery rates to nests showed an increasing trend as the nestling period progressed. This was significant in the lake environs where brood sizes were larger than in Hell's Gate. Overall nestling feeding rates were also significantly greater in the lake environs than in Hell's Gate. Augur Buzzards in Hell's Gate spent significantly more time interacting with conspecifics and other species compared to those in the lake environs. We suggest that reduced predation pressure from conspecifics and other raptors in the lake environs as a result of lower inter-/intra-specific interactions enabled Augur Buzzards to maximise provisioning of their young hence potentially increasing productivity.