Eptesicus regulus

Abstract: The diets of seven of the eight species of insectivorous, vespertilionid bats found in Tasmania were studied in forest areas. The diet of the eighth species, Chalinolobus gouldii, was studied in riparian woodland surrounded by open pasture. Nyctophilus timoriensis was found to be a gleaner with most of its diet consisting of non-volant insects. Five of the species (Eptesicus vulturnus, Eptesicus regulus, Eptesicus sagittula, Nyctophilus geoffroyi and Chalinolobus morio) fed opportunistically, their diets reflecting local and temporal variations in insect abundance and diversity. Lepidoptera made up most of the diet of these species. The largest species, Falsistrellus tasmaniensis, appeared to be a selective feeder, with Coleoptera being the most important item in its diet. Coleoptera also made up the bulk of the diet of C. gouldii, but caterpillars were also important. For the species studied in forest areas, there was a highly significant correlation between the mean sizes of the lepidopterans (r= 0.95) and coleopterans (r = 0.96) eaten and the size of the bat. For all bats larger than E. sagittula, the mean size of beetles eaten was smaller than the mean size of moths eaten. These results are in accord with expectations from optimal foraging theory.

Abstract: Activity and weight changes were studied over a year at an area in south-eastern Tasmania where all eight species of Tasmanian bats were present. Activity was lowest in winter and highest in spring. Low levels were recorded during December and January, probably due to heavy rain. High levels of activity in May coincided with mild temperatures and may have taken advantage of emergence of moths at this time. A greater proportion of Chalionolobus morio were caught from May to August in comparison with other species. Sex ratios of captured individuals differed significantly from parity for C. morio, Falsistrellus tasmaniensis, Eptesicus regulus and Nyctophilus geoffroyi. For C. morio, the proportion of males captured increased during the colder months. For E. regulus, the proportion of females caught increased asymptotically as the capture rate for this species increased. Weights of bats varied over the year. For female E. regulus and N. geoffroyi, weight peaked in late pregnancy and dropped over winter, but for C. morio weight was similar at the end of autumn and early spring. For male E. regulus, weights were highest in autumn and showed no decline over winter, but for C. morio weights were greatest during mid-winter. C. morio is more active than other bats during colder periods and may rely on reduced competition with other species at these times to build up fat reserves.

Abstract: Analyses of morphological divergence in male and female Eptesicus in Western Australia are detailed. Phenetic differences between individuals at each locality, or nearby groups of localities, are examined for males and females separately, by canonical variate analysis. Populations can be roughly grouped into those of the South-west, North-west-Desert, Pilbara, Kimberley and the Peninsulas. Trends are evident from the analysis of the regional data for external morphological measurements. The South-west populations are referable to Eptesicus regulus Thomas, 1906. The moderately large Northwest-Desert populations are considered part of a general cline of Eptesicus pumilus extending north through the intermediate-sized Pilbara populations to the small Kimberley populations. The Peninsula populations have their greatest phenetic affinities with Eptesicus douglasi. In all populations examined, female Eptesicus tend to be larger than males.

Abstract: Roosting requirements and movements between foraging areas and roost sites were studied in Eptesicus regulus, E. sagittula, Chalinolobus morio and Nyctophilus geoffroyi in an area of artificially regenerated eucalypt (Eucalyptus) forest surrounded by mature eucalypt forest. Movements between traps and roost sites were normally about 1 km, with the maximum distance recorded being 4.8 km for a female N. geoffroyi. Different species of eucalypts were used as roost sites in proportion to their occurrence in the forest. However, large trees over 80 cm d.b.h. were favoured. There was no tendency to avoid roost sites close to the ground. Spaces used as roost sites had one dimension little greater than the bat itself. Five types of roost sites were distinguished: in fissures, inside burnt-out boles, in hollows, under bark and on the ground. Individuals changed roost sites frequently but roosts used by any one individual were in the same general vicinity. The factors associated with production of roost sites in trees were: large size, overmaturity, death, rot and fire. No bats were found to roost in regenerated forest. Patches of mature forest will need to be retained to ensure a shortage of roosts does not occur as more areas of mature forest are converted to production forest.