The diet of a Sooty Owl from Yarrangobilly Caves, NSW

ABSTRACT A total of 783 dietary items from a Sooty Owl Tyto tenebricosa tenebricosa with suspected partial xanthochromism (yellow plumage colouration) was identified from Yarrangobilly Caves, NSW. Observations of the owl at the cave and collection of feathers suggest that prey items accumulated between 2011 and 2018. A total of 12 mammal species was detected in the diet, with the Bush Rat Rattus fuscipes, Agile Antechinus Antechinus agilis, Sugar Glider Petaurus breviceps and Rabbit Oryctolagus cuniculus dominating. The diet also included three threatened species, the Eastern Pygmy Possum Cercartetus nanus, Smoky Mouse Pseudomys fumeus and Broad-toothed Rat Mastacomys fuscus. The diversity of prey identified in the diet contrasts markedly with that found in studies of subfossil deposits from the area, supporting evidence of extensive mammal declines since European settlement.

Monitoring of small mammal populations in the Brindabella Ranges after fire

We live-trapped small mammals in the Brindabella Ranges west of Canberra, Australian Capital Territory from April 2009 until October 2011 to assess population recovery after an intense and widespread fire that occurred across the region in 2003. Three native mammals (agile antechinus, Antechinus agilis; dusky antechinus, Antechinus swainsonii; bush rat, Rattus fuscipes) were encountered. Trapping records and spool-and-line movement patterns suggested a strong association of these small mammals with moist gully vegetation that had survived the fire.

Early onset of reproduction in the agile antechinus, Antechinus agilis

Ovulation in the agile antechinus, Antechinus agilis, usually occurs when the rate of change of photoperiod in spring is increasing at 127–137 s day–1. We report responses to a much slower rate of change of photoperiod in a population in far east Gippsland, Victoria, and discuss the ecological consequences and management significance of early breeding.

Small mammal populations in a eucalypt forest affected by fire and drought. I. Long-term patterns in an era of climate change

This paper reports a study of ground-dwelling, small mammals in coastal eucalypt forest in south-eastern Australia from 1970 through 2005. During this time, the study area burnt in an intense fire in December 1972 and was partially burnt in November 1980. Both fires were associated with prolonged drought. The mammals studied comprised two dasyurid marsupials, Antechinus agilis and A. swainsonii, two native murid rodents, Rattus fuscipes and R. lutreolus, and the introduced house mouse Mus musculus. After intensive sampling throughout the year from 1970 through 1972 to establish basic ecological and population parameters of the small mammal community, populations were sampled annually during late autumn and early winter before the onset of breeding. There were marked differences in the annual (autumn/winter) abundances of all species; numbers of A. agilis ranged from 4 to 142 individuals; A. swainsonii 0 to 43; R. fuscipes 4 to 54; R. lutreolus 0 to 11; M. musculus 0 to 23. Following the 1972 fire, numbers fell to the lowest level recorded during the study and each population subsequently disappeared from the plot between the 1973 and 1974 winter censuses. The less intense 1980 fire did not lead to extirpation, but numbers of A. agilis, A. swainsonii and R. fuscipes declined as drought conditions persisted through 1983. R. lutreolus occurred consistently only following the fires, when a grassy ground vegetation favoured by this species developed. Similarly, M. musculus colonised within two years of the fires and persisted on the plot for 3–4 years before disappearing. Following the fires, populations of the omnivorous R. fuscipes recovered first followed by the scansorial, insectivorous A. agilis and last by the fossorial, insectivorous A. swainsonii. Two primary conclusions emerged from this study. First, the intense fire of 1972 did not kill all the animals immediately, but led to the disappearance of each species from the plot over 18 months. Thus, intense fire had a delayed but catastrophic impact on small ground-dwelling mammals. The fluctuations in population levels, covering more than an order of magnitude, demonstrate that factors other than fire, such as rainfall and drought, drive the population dynamics of these small mammals. As stability and recovery are not features of local populations, long-term studies of benchmark populations are necessary to manage forest biodiversity.

Effects of drought on weight, survival and breeding success of agile antechinus (Antechinus agilis), dusky antechinus (A. swainsonii) and bush rats (Rattus fuscipes)

Extreme weather conditions, such as drought, significantly decrease the survival and breeding success of numerous species. Despite the frequent occurrence of such conditions in Australia, little is known about the effects of changing environmental conditions on the native small mammals. This study, conducted from 2002 to 2004, focussed on sympatric wild populations of the agile antechinus (Antechinus agilis), with more limited information on the dusky antechinus (A. swainsonii) and the bush rat (Rattus fuscipes). Bodyweights of agile antechinus before and during the breeding season were significantly lower in 2003 (drought) than in 2002 or 2004. Survival of female agile antechinus and the number of young per litter also decreased significantly during drought. In contrast, the dusky antechinus showed no difference in mean bodyweights between years, high survival rates of females and similar litter sizes in 2002 and 2003. There was also no difference in bodyweight of bush rats between years. Low rainfall was recorded during pregnancy and lactation in the agile antechinus, but rainfall was higher during pregnancy and lactation in the dusky antechinus. The survival and breeding success of the agile antechinus may have been adversely affected by a combination of interspecific competition, timing of the breeding season and severity of the drought.

morphometric variation associated with teat-number differences in Antechinus agilis and A. swainsonii ? Observations from the Otway Ranges, Victoria

That there is intraspecific variation in teat-number in Antechinus agilis (agile antechinus) and A. swainsonii (dusky antechinus) has been known for a long time. Our aim was to determine whether other key morphometric traits differed among individuals with different numbers of teats. External body dimensions and pelage characteristics were measured on live individuals and compared. Within-species variation in some external body dimensions (tail, pes, and snout-vent length) coincided with teat-number differentiation in both antechinus species in the Otway Ranges, Victoria. Disparities in pelage colour and markings were apparent between A. agilis 6- and 10-teat phenotypes, but were not obvious among A. swainsonii teat phenotypes. Although small sample sizes obviated statistical analysis, we tentatively concluded that female A. agilis with 7, 8, or 9 teats in the Otway Ranges probably displayed morphometric and pelage characteristics intermediate between those of 6- and 10-teat individuals. A comparison of morphometric traits among 6-teat A. agilis from different geographic areas (Otways, Portland and Wilsons Promontory) also revealed some variation. This result was consistent with an expectation of clinal variation in external morphology among antechinus. Overall, this study indicates that localized disparities that are associated with teat-number, as well as clinal differences occurring over large geographic distances, contribute to intraspecific variation in external morphology in antechinus.