Demographic responses of Antechinus stuartii (Marsupialia) to supplementary food

This study investigates the effects of supplementary feeding on populations of Antechinus stuartii, an insectivorous, semi-arboreal species of dasyurid marsupial. Animals were live-trapped, marked and released in three study areas in forest near Canberra, from September 1980 to November 1981. Supplementary food was supplied above ground in trees in one study area from January to November 1981, and in the second study area from January to May 1981, while the third study area was left unmanipulated as a control. The supplemented populations increased in numbers, mean body weights and survival, and showed decreased movements between traps and smaller overlaps in home ranges. Discontinuation of food in the second study area in May 1981 produced reciprocal shifts in these parameters. Reproduction, home-range area, mean head-body length, use of the terrestrial and arboreal parts of the habitat were largely unaffected by provision of supplementary food. In contrast to rodents, where fed populations usually increase rapidly due to immigration or increased reproduction, the supplemented populations of A. stuartii responded relatively slowly via increased survival of young. Population responses were probably retarded at the beginning of the experiments in summer due to the abundance of natural invertebrate prey, but became more obvious in winter when natural food was scarce. The added food probably contributed directly to increased numbers, survival and body weights, but may also have enhanced these parameters indirectly by allowing foraging animals to space out and avoid intraspecific intolerant contacts. These responses in A. stuartii suggest strongly that populations are limited by the food supply.