We examined how a community of insectivorous bats in upland rain forest differentially used closed canopy areas and artificial gaps produced by selective logging. Bat foraging activity was monitored at paired canopy and gap sites using ultrasonic detection equipment. The data supported the prediction that gap use was related to morphology and bat species were classifiable as closed canopy specialist, gap specialists, and gap incorporators. Closed canopy specialists were species with low aspect ratio and wing loading, whereas gap specialists had high values for these two measures. Gap incorporators, which used both canopy areas and gaps, were intermediate in morphology. The closed canopy species were presumed to forage more readily in a cluttered environment. In this community there were no strict gap specialists, but instead the gap specialists were also recorded in other, more open habitats. The community consisted of two distinct subcommunities: four species in closed canopy areas and five in gaps. Three other species were incorporators, but the incorporation rate was very low; only 8% of the activity in gaps and 27% in closed canopy areas was due to these species. There was no relation between patterns of gap use and gap vegetation cover or age up to 6 yr, suggesting that exclusion of gap specialists from a regenerating gap is a slow process. There is tight phenetic packing in the two subcommunities, indicating that vegetation structure is more important than competition in constraining the structure of this community.
The flight activity of insectivorous bats from two high-altitude regions in coastal north Queensland was measured over three years at irregular intervals and at night temperatures ranging from 7.3 to 268°C. During the latter part of the study, potential insect prey were light-trapped from one of the study areas. For all but one of the 353 records of bats obtained in 166 surveys, ambient temperatures exceeded 15°C. The dry weights of light-trapped insects were significantly reduced when night minimum temperatures were below 16°C. This study shows that high-altitude areas in Australia's tropics have a bat activity pattern similar to that recorded in temperate areas, and that the drop in winter bat activity is presumably a response to the lack of insects caused by cool temperatures. The period between birth and weaning exhibited by many bat species coincides with that part of the year when minimum night temperatures exceed 15°C. Cognizance of this behavioural pattern is necessary in the study of bat communities in montane regions of Australia's tropics.
Rates of water turnover were measured in free-living rabbits during a period of wide variation of climate and water availability. Mean rate of water turnover was positively correlated with the hydration of the pasture (r = 0.987).
Mean turnover rates per day ranged from 214.3 ml kg-1 in
cool, wet conditions to 55.4 ml kg-' in a moderate summer drought. The lowest individual rate was 46.1 ml kg-1 per day. The rate of water turnover in young rabbits (1-2 months old) was significantly higher than that of adults measured at the same time; this may contribute to the low survival of young rabbits in dry seasons.
A comparison of the rates of water turnover from lactating
rabbits in wet and dry seasons shows that the estimated milk production under dry pasture conditions is below that required to maintain a litter of young.
Baculum shape and skull and body measurements were used to evaluate the forms of Eptesicus occurring in Australia. Four species, one of which comprised two subspecies, are recognized. An additional form, E. douglasi, was not intensively studied but is accepted as a full species. Names were available for all forms except one, which is described as E. sagittula, sp. nov.
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