Population dynamics, diet and aspects of the biology of feral cats and foxes in arid South Australia

Abstract

Average cat and fox densities at Roxby Downs, in northern South Australia, of 0.8 and 0.6 km–2 respectively, determined through spotlight counts over a 10-year period, probably considerably underestimate true densities. Peak rabbit populations coincided with high fox numbers, which probably suppressed cat densities. Cat abundance peaked when fox numbers were low but rabbit numbers were relatively high. When abundant, rabbits were the principal prey of both cats and foxes. Declines in rabbits numbers coincided with dramatic declines in fox numbers. By contrast, declines in cat populations were less marked, presumably because they could more effectively switch to hunting a wide range of native vertebrates. Sand-dwelling lizards, house mice and common small passerines were the most abundant non-rabbit, vertebrate prey taken by cats. We estimate that annual cat predation accounted for approximately 700 reptiles, 150 birds and 50 native mammals per square kilometre, whereas foxes consumed on average 290 reptiles per square kilometre and few native mammals and birds in the Roxby Downs region each year. Male cats and foxes were heavier than females. Feral cats typically weighed less than 4.0 kg, and cats weighing less than 2.5 kg typically preyed on more native vertebrates than did larger cats. Male and female cats were both typically tabby coloured, but a higher proportion of males were ginger in colour. Peak cat breeding coincided with rabbit and bird breeding and increased reptile activity during spring.

Catastrophic cat predation: A call for predator profiling in wildlife protection programs

“…Only a single duck, a grey teal, was recorded in the stomach of over 2000 feral cats dissected at Roxby Downs (see Read and Bowen, 2001) yet the same 1.5 kg male cat that had consumed the teal was shot whilst swimming out towards other ducks, suggesting that the offending cat had learned to target these unusual and challenging prey (Read and Ebdon, 1998). An individual 3.5 kg male cat was photographed making two kills of brown boobies, Sula leucogaster, (mean weight 0.9-1.5 kg, wingspan 1.3-1.5 m) on Hahajima Island, Japan; (Plate 1).…”

“…Western quolls weigh between 1 and 2 kg and are carnivorous marsupials, feeding on a range of invertebrates, birds, small mammals and reptiles (Rayner et al, 2011). Being a medium-sized carnivore capable of killing prey the size of rabbits, western quolls were predicted to present more challenging prey for cats than the small rodents, rabbits, lizards and birds that constitute the majority of regional cat prey (Holden and Mutze, 2002;Molsher et al, 1999;Read and Bowen, 2001). Western quolls are believed to have become extinct from South Australia's Flinders Ranges in the 1880s (Tunbridge, 1991) possibly due to a combination of disease and predation from introduced cats Peacock and Abbott, 2014).…”

Receiving behaviour is sensitive to risks from eavesdropping predators

“…Mice are common prey for a variety of predators, including the cat (Felis catus; Read and Bowen 2001;Newsome 2002), another introduced pest species with which they share a long evolutionary history. Cats use mouse odours to Wnd their prey (Fitzgerald and Turner 2000), and wild mice avoid cat odours (Dickman 1992;Drickamer et al 1992) and use denser vegetation when the density of cat faeces is increased (Dickman 1992).…”

Effects of feral cats on the evolution of anti-predator behaviours in island reptiles: insights from an ancient introduction

“…We measured the density of cats along 1 km long road transects by moving at about 4 km h 21 and searching 50 m on both sides using a hand-held spotlight (Cyclops CYC-9WS; Cyclops Solutions, Grand Prairie, TX, USA) [20]. Surveys were conducted at the same time (21.00-00.30) during clear and windless nights.…”