|
Studies of large mammalian herbivores point to the importance of food quality and quantity in determining population size. Graziers in the New England Tablelands of New South Wales claim that an increase in numbers of eastern grey kangaroo and wallaroo occurs after pasture improvement measures are adopted on a property. In this region properties are present which differ in pasture management and also support sympatric populations of grey kangaroo and wallaroo. This allowed a study to be made of the comparative ecology of the two kangaroo species in areas differing in the quality and quantity of food present in order to investigate the graziers' claims. The study was conducted on two properties which were within 40 km of each other. These properties had similar rainfall and temperature regimes but differed markedly in the intensity of pasture management for domestic stock. One of the properties, Lana, had been selectively cleared of trees and an intensive program of fertilization of pastures and introduction of exotic pasture plants had been carried out. The other property, Newholme, had had no application of fertilizers and no exotic pasture plants introduced. On Newholme large areas with a dense tree canopy remained and other areas had been totally cleared of trees. The grey kangaroo population on Lana was regularly culled. No grey kangaroo on Newholme, or wallaroo on either property, were harvested. Within their occupied habitats the density of wallaroo was estimated to be seven times greater on Lana than on Newholme and the density of grey kangaroo on Lana was estimated to be double that on Newholme. |
|