Aspects of the ecology of the Thomson's gazelle in the Serengeti National Park, Tanzania

Abstract

Four subpopulations of Thomson's gazelle in the Serengeti National Park were designated as Serengeti Main, Loliondo, Loita, and Kirawira. Seasonal distribution of subpopulations within the Serengeti was illustrated. The movements of the Serengeti Main were correlated spatially and temporally with rainfall. Where the choice existed the gazelle preferred that zone of the rainfall spectrum averaging 50 to 65 mm of precipitation. Censuses using random points and systematic points along random transects were used to ascertain the population size for the Serengeti Main subpopulation. The best estimate of the gazelle population was 725 000. Monthly transects over a period of 22 months were made to ascertain seasonal changes in the sex and age structure. A technique of logarithmic transformations of age class and ratios and cross-correlation was developed as a means of calculating the chronological age of the subjective field age categories. Sex ratio changed from a fetal ratio of 191 males per 100 females to 115:100 for newborn gazelles to parity for juveniles. The adult ratio was further reduced to 58.5 males per 100 females.