Ardea
Official journal of the Netherlands Ornithologists' Union

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Lack P.C. (1986) Ecological correlates of migrants and residents in a tropical African savanna. ARDEA 74 (2): 111-119
The 115 commonest landbird species occurring in Tsavo East National Park in south-eastern Kenya were divided into four main food categories: insect, fruit, seeds and nectar; and three status categories: resident, visitor from within Africa and migrant from the Palaearctic. Many visiting species were only present during the wet seasons although all seasons supported a few. Resident species occurred in a smaller range of habitats than either visiting group although there were no significant differences in the particular habitats occupied by species within each group. Over three-quarters of all species were at least partially insectivorous including all the migrants from the Palaearctic, and nearly half the African visitors were granivorous. All species which were at least partially frugivorous except two were resident. Visiting species had a narrower range of foods than residents. Among the insectivores, residents fed more on small items from the ground and visiting species fed more from green vegetation, in the air, and by pouncing to the ground for larger items. The results are compared with studies in the Palaearctic. In Tsavo the residents seemed to divide the area more by habitat than food. They are perhaps forced to be food generalists because of harsh conditions in the dry season. Many of the visitors exploit resources which are only seasonally available.


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