Population size, morphometrics and movement patterns of the brush-tailed mulgara (Dasycercus blythi): is predation by mammalian predators having an effect?

Abstract

Worldwide predation by feral cats has caused severe declines in many animal species. Prior to extinction, threatening processes typically alter species behaviour, habitat use, survival and reproductive rates. By monitoring these parameters, we may be able to determine if feral cats are a significant threatening process to a species prior to extinction. We aimed to test whether feral cats are negatively affecting the population size, morphometrics and movement patterns of mulgaras (Dasycercus blythi) on the Matuwa Indigenous Protected Area, in the arid rangelands of Western Australia. We hypothesised that mulgaras, which inhabit a cat-free environment, would have a larger home range and denser population, and be in better condition than those that inhabited an adjacent area with a suppressed density of feral cats. We trapped (n = 64), and radio-tracked (n = 19) mulgara inside and outside an 1100 ha cat-free fenced enclosure on five occasions in 2012. Treatment (i.e. inside or outside the cat-free enclosure) was a significant variable for explaining variation in mulgara density. There was no significant difference in morphometrics or the home ranges of mulgara between the sexes or treatments. Head length, pes length and weight, as well as tail width and length, were significantly different between sexes and over time, suggesting that seasonal variation influences mulgara populations more than low levels of cat predation.