WHAT DETERMINES PHENOLOGY AND SYNCHRONY OF UNGULATE BREEDING IN SERENGETI?

Abstract

Birth seasons of ungulates in tropical regions show a complex pattern varying from asynchronous to highly synchronous and at different times of year. We examine the factors determining the phenology and synchrony of birth seasons of 13 species of ungulates in the Serengeti ecosystem, Tanzania. We propose that phenology of births (time of year) is determined by food supply, whereas birth synchrony (degree of coordination or spread) is an antipredator adaptation that functions in two different ways. High synchrony may occur through “predator satiation” in species with precocious newborn (“followers”), whereas asynchrony may occur through “predator avoidance” in species with nonprecocial young (“hiders”). We used green biomass of grass or tree shoots and percentage crude protein as measures of food supply. Births were determined from monthly sample counts covering the period 1967–1997. The frequency distribution of births was compared to that predicted by the abundance of green biomass and percentage protein...