The population dynamics of nilgai (Boselaphus tragocamelus Pallas) in South Texas, with some management considerations

Abstract

Free ranging nilgai on the Norias Division of King Ranch, Inc., were studied during the period of 1971-1974 to derive information about the dynamics of population processes and their interaction with behavior and range management problems. A sample of the population was obtained by aging and sexing animals which perished during a catastrophic winter die-off in 2 pastures during 1972/72. This data was used to complete a life table and assess various age specific parameters of reproduction and morality. Historic and recent population trends are examined. Animals which died during the winter of 1972/73 were necropsied and the results were analysed to determine probable causes of mortality. Availability of forage was measured in 3 strata of stocking/treatment combinations on 2 range sites in which animals perished and in two control areas in which animals did not. Patters of forage availability followed through forage recovery and results of the pathological analyses suggested that shortages of high quality forage combined with extremely severe winter weather induced a change to protein metabolism in the animals which resulted in death.