Suchergebnisse

A survey was conducted in the Northern Temtory and Queensland to determine the distribution, status and
habitat use of the recently described Carpentarian rock-rat, Zyzomys palatalis. The species was previously
known from two localities in the Gulf of Carpentaria, and this survey added only one new population to its
known range. The species is restricted to monsoon rainforest on scree slopes. In the Gulf region this habitat
is very limited and highly fragmented. The only areas where suitable habitat exists are in relatively
inaccessible gorges where permanent springs provide enough moisture to maintain the monsoon rainforests.
These patches of relict vegetation may be threatened by feral animals and changing fire regimes.
Because of the low population size of Z. palatalis and the small size of suitable habitat available, the
species is considered to be critically endangered.

Rhinonycteris aurantius has a seasonally monoestrous reproductive pattern. Males do not become sexually
mature until their second year, at about 16 months of age. Mature spermatozoa were observed in the testes
in April, with increasing numbers of sperm recorded until copulation in July, declining numbers from
August to October and none observed during the wet season from December to March. Females attain
sexual maturity at seven months of age. The gestation period is prolonged (approximately 150 days) from
July to December with the young weaned and independent by late February. Despite this species' utilisation
of hot and humid caves during the dry season, late pregnancy, parturition and weaning take place away
from the cave environment.
The first three months of pregnancy in females and the production of sperm in males occurs during
periods of low food availability. However, there is coincidence of maximum food availability with late
pregnancy and lactation, obviating sperm storage and/or delayed embryonic development.

Results of faecal analysis were compared with insect captures in light traps to examine the dietary preferences of R. aurantius in the Northern Territory, Australia. Relative proportions of insects eaten differed significantly from insects available. R. aurantius exhibited a medium niche breadth throughout the year, being neither a specialist not a generalist. It selectively foraged on Lepidoptera and Coleoptera, and was opportunistic in regard to seasonal abundances of Isoptera. This bat had dietary preferences similar to other members of the Hipposideridae. The timing of reproduction and selection of roost sites was related to the seasonal abundance of food resources.

Temperature and humidity were recorded from roost sites used by nine species of cave bats in northern
Australia. The 10 sites containing R. aurantius exhibited the narrowest range of roost conditions of
any species, this species having a strong preference for hot and humid roosts (28-32�C and 85-100%
RH). R. aurantius colony sizes ranged from 20 to 25 000, and varied seasonally, almost all colonies
abandoning their cave roosts during the wet season. Colony size was strongly related to mean minimum
monthly temperature and rainfall, populations being greatest during the coolest and driest period of
the year. Other sympatric species also exhibited preferences for specific roost conditions, indicating
interspecific partitioning of roost resources. Species that utilised a broad range of roost humidity
occupied a larger geographic range than those with more specific requirements.