Drought Refugia Research Articles

Joint use of habitat by red kangaroos and shorthorn cattle in arid central Australia

Abstract The distribution of cattle and red kangaroos among the major communities of a 170 km2 paddock in central Australia was determined from 108 and 82 air surveys respectively over a four and a half year period. Fifty‐nine surveys of each species were used in this report. Changes in use of the communities by the two species were analysed in relation to forage conditions using linear regression techniques. The two species showed trends in time of use of the open and wooded communities. Kangaroos used the mulga‐perennial community (groved Acacia woodland with a shrub and perennial grass understorey) during good forage conditions and moved to the drought refuge open communities when forage conditions deteriorated. Cattle, on the other hand, used the open communities during good forage conditions and tended to move to the mulga communities and the hills when drought began. Mulga‐annual (ungroved Acacia woodland with short grass and forb understorey) was the only major community which showed no clear linear relationship between kangaroo use and forage conditions. This might be a buffer area from which kangaroos come and go as other areas become more attractive as feeding areas. Cattle, however, show some preference for mulga annual during medium forage conditions. There appears to be little spatial interaction by the two species except during drought when kangaroos concentrate on the open communities and some cattle continue to feed in these communities. Community selection seems to be determined mainly by forage conditions, as there is no evidence that one species attracts or repels the other in spatial terms. In the conditions observed, the two species successfully coexisted with some control of numbers of cattle by man.

Waterfowl in an inland swamp in New South Wales. 2. Food

The food of nine species of waterfowl has been studied in a drought refuge during a period of moderately severe drought. The species involved were the black swan, freckled duck, black duck, grey teal, shoveler, pink-eared duck, hardhead, musk duck, and blue-billed duck. In all, 3697 gizzards were examined. Although the black swan had certain food plants in common with most other species, particularly during periods of drought, and although the black duck and grey teal had nearly identical food requirements, serious competition between these species was considered unlikely for various reasons. Otherwise, the species were well separated in their feeding places, depths of water utilized, and food collected. The value of cumbungi swamps as drought refuges is discussed and the adaptations of the waterfowl in utilizing these swamps are examined.

The distribution of red kangaroos, Megaleia rufa (Desmarest), about sources of persistent food and water in central Australia.

Data from aerial surveys primarily designed to estimate the numbers of red kangaroos, Megaleia rufa (Desmarest), on about 4000 square miles of central Australia have been used to define the animals' distribution about sources of persistent food and water, both during severe drought and 6 months later after good rains had fallen. During the drought, 67.4% of kangaroos were sheltering in woodlands within 1/3 mile of open plains and water-courses (where food persisted), and only 17.4% were further than 1 mile away. After the rains, only 29.5% were within 1/3 mile of these drought refuges; 51.8 % were further than 1 mile away, but only 6% were beyond 6 miles out, i.e. beyond the mulga woodlands. Kangaroos were densest (seven-eight per square mile) during drought on land 2-4 miles out from bores and dams and within 2/3 mile of open plains because at that distance grasses on the plains respond to the grazing of cattle by sprouting green shoots which kangaroos prefer. Kangaroos drank at the bores and dams only during severe drought and may, therefore, get sufficient water from their food at most times. It is concluded that the kangaroos' distribution and changes in it are controlled primarily by their search for green herbage and shady trees.