PATTERNS OF ARRIVAL AND DISPERSAL FROM A MIXED COMMUNAL ROOST OF SACRED IBISES AND MARABOU STORKS

Abstract

Summary Evans, S. M., Cantrell, M. A. & Cram, A. 1982. Patterns of arrival and dispersal from a mixed communal roost of Sacred Ibises and Marabou Storks. Ostrich 53:230-234. A communal roost of Sacred Ibises Threskiornis aethiopicus and Marabou Storks Leptop-tilus crumeniferus is described near Nairobi in Kenya, East Africa. Marabous came to roost from mid-afternoon, circling on thermals before alighting, or on direct flight paths. Agonistic encounters between Marabous were common and perched birds (numbering about 150) spread out and occupied most of the 30 trees in the roost. In contrast. Sacred Ibises arrived at dusk (about 250 birds) flying in groups and settled among Marabous on a few selected trees. Although arrival times were different, Sacred Ibises and some Marabous departed the roost at the same time each morning soon after dawn. Flight directions were non-radial, the majority of both species flying directly to an area where food in the form of factory waste was deposited. Food was locally abund...