An Analysis of Avifauna‐Resource Relationships on the Serengeti Plains

Abstract

The objectives of this study were: (1) to test the hypothesis that food was the principal proximate factor limiting the distribution of birds on the Serengeti Plains of Tanzania, and (2) to generate a satisfactory description of the relationships of the Serengeti avifauna to selected habitat factors. I analyzed natural changes in the avifauna among habitats through time and related these changes to variation in avian food and habitat resources. Food limitation was apparently not an important proximate factor affecting short—term variations in bird population densities, although many species were functionally capable of responding to fluctuations in food supply. Habitat partitioning was the principal means of "niche segregation" among the various species. Sites with greatest total avian biomass had low vegetation biomass, low vegetation height, but well—developed vertical vegetation structure. These conditions provided cover along with a great degree of ground—level mobility for most species. Individual bird species were associated with specific types of vegetation structure, while vegetation condition (primarily green biomass) was the main factor associated with increased densities of bird species within vegetation types. Neither conventional competition theory nor Wiens' (1977) "bottle—neck" theory can account for the characteristics of the Serengeti grassland avifauna.