Growth, body condition and demography of wild banteng (Bos javanicus) on Cobourg Peninsula, northern Australia

Abstract

Growth, body condition and demography of a sample of 125 banteng, Bos javanicus, from a largely unharvested wild herd on Cobourg Peninsula in northern Australia were examined. Growth (measured as changes in age‐specific head‐length) was sexually dimorphic, males growing faster and attaining larger sizes than females. Females reached maximum size in three to four years, and males in five to six years. Body condition (measured by the kidney‐fat index) was low amongst juveniles, increasing into middle age. Condition of aged females showed a marked decline. Males attained sexual maturity between three and four years, females between two and four years. Fecundity declined in older females. Breeding was seasonal, mating activity peaking during October and November, with births most frequent between June and August. Mortality amongst calves was high over the first six months of life, declining rapidly amongst older animals. Comparison of demographic data with those reported for captive herds indicates that the wild banteng in this study matured later, were less fecund, and suffered a higher rate of juvenile mortality. Lower fecundity and higher juvenile mortality were associated with patterns of age‐specific body condition, suggesting that food availability was the major factor affecting demography and hence rates of change in banteng abundance.