Forage-Habitat Relations of Nonmigratory African Ungulates in Response to Seasonal Rainfall

Abstract

Four species of nonmigratory ungulates in Lake Nakuru National Park, Kenya, underwent seasonal shifts in foraging by utilizing 6 distinctly different forage-habitats. These ungulates are successful because they rely upon a wide range of food resources to cope with seasonal changes in climate. Management of these ungulates can be approached by the recognition, monitoring, and maintenance of the needed array of forage-habitats. Those utilized during the dry periods were most critical. J. WILDL. MANAGE. 43(4):899-908 East Africa is noted for its diversity and abundance of large mammalian herbivores. While various classification schemes have been used to describe the ecology of African ungulates (Lamprey 1963, Jarman 1974), in this study I have found it useful to divide the ungulates into 2 general categories: migratory, in which the home range is large; and nonmigratory, in which the home range is small (Talbot 1963). Both groups live under climatic conditions in which the rainfall patterns are highly variable and seasonal (Griffiths 1972). Under this regime, the nutritional quality of many forage species varies greatly with the available moisture (Dougall et al. 1964, Lawton 1968, Field 1971). Ungulate migrations seem to be a response to water availability and forage quantity and quality (Bourliere and Hadley 1970, Pennycuick 1975). Migratory animals must satisfy their nutritional needs by moving, sometimes over great distances, to the best quality of food resources available at any given time of the year. Moreover, migrating ungulates feed upon a narrow range of forage components, i.e., on only a few forage species (Talbot and Talbot 1963) or on a specific growth stage or stratum of vegetation (Vesey-Fitzgerald 1960, Bell 1969, McNaughton 1976). But what of nonmigratory ungulates? Faced with seasonally fluctuating conditions, how do they satisfy their nutritional needs while restricted to small home ranges? Although no data were put forth, Talbot (1963) suggested that nonmigratory ungulates are mixed feeders eating a variety of foods during different seasons. This hypothesis had never been directly tested even though it was intended to explain how a large group of ungulates copes with seasonal changes in climate and vegetation on the African savanna. From the pragmatic viewpoint, a number of small reserves have recently been established containing nonmigratory ungulates almost exclusively. This study, therefore, was undertaken to test the hypothesis and to examine the management implications of maintaining nonmigratory large mammals on small areas of land. I thank Kenya National Parks for permission to carry out the research, and G. Petrides, R. Baker, W. Conley, L. Gysel, and H. Shellhammer for editorial advice. This paper is dedicated to the memory of Robert K. Pool, former Director of the Peace Corps in Kenya and of the African Wildlife Leadership Foundation in Nairobi. His boundless energy and enthusi1 Supported by a Foreign Area Fellowship from the Council of Learned Societies. 2 Present address: Department of Biological Sciences, San Jose State University, San Jose, CA 95192. J. Wildl. Manage. 43(4):1979 899 This content downloaded from 207.46.13.184 on Fri, 29 Jul 2016 05:40:53 UTC All use subject to http://about.jstor.org/terms 900 HABITAT OF AFRICAN UNGULATES * Kutilek