Feral cat (Felis catus) prey size and selectivity in north‐eastern Australia: implications for mammal conservation

Abstract

The domestic cat Felis catus is distributed worldwide and has had a long historical relationship with humans. In some regions, such as Australia, it has become feral and a significant predator of native wildlife. A key component of quantifying and managing the conservation threat of introduced predators is an understanding of exactly what size and taxa of prey species are consumed, and whether there is a high degree of selectivity in the diet. A total of 169 cat stomachs were collected from north‐eastern Australia, and their contents examined in relation to prey size, the body size of cats and selectivity using Jacob's index. I found that F. catus contains a large amount of prey per cat (∼200 g), mammals are the dominant prey item by mass, and feral cats predation was selective of small mammals (<10 g, 50–100 g), and reptiles and birds in the 10–50 g and 50–100 g size ranges, respectively. Reptiles form a large component of the diet compared with other regions in the world. Many mammals in northern Australia that are declining are within the size range that is highly selected by feral cats; the relationship between smaller cat size in the tropics and smaller prey size has correspondence to the fact that the declining mammals in this region are smaller than those that went extinct in southern Australia. There is an urgent need to find a conservation solution to reducing feral cat predation on wildlife, and this should include landscape scale reduction in fire extent and frequency, and removal of cattle in key sites, in order to maintain ground cover, thus reducing the predation success of feral cats.

Diet of the feral cat, Felis catus, in central Australian grassland habitats during population cycles of its principal prey

“…Although our sample sizes were quite different between periods, we were still able to confirm that the diets of feral cats during the bust period were much more diverse than those of their counterparts during the boom. This difference has implications for wildlife conservation and feral cat control, as although none of the prey species identified in the diet is listed as threatened, all are native Australian animals and may be at risk of becoming threatened if feral cats switch to hunting them on a consistent basis after periods when favoured prey have declined (Kutt 2011(Kutt , 2012.…”

“…Working in Mitchell grass habitat to the northwest of our study region, Mifsud and Woolley (2012) reported broadly similar results for cat diet to those presented here, and noted that venomous prey such as elapid snakes and centipedes were taken frequently when principal prey (R. villosissimus) became scarce. In the same region, Kutt (2012) used both dietary analyses and estimates of prey availability (Kutt and Woinarski 2007) to show that feral cats generally select prey items such as small mammals (<10 and 50-100 g) and amphibians and reptiles (10-50 g), and avoid other prey such as large birds. The broader diet of cats in our study during the bust compared with the boom period is consistent with the idea that cats switched to alternative prey when small mammals became scarce, but also cannot preclude the possibility that cats selected alternative prey during bust conditions.…”

Ongoing unraveling of a continental fauna: Decline and extinction of Australian mammals since European settlement

“…One recent controlled experiment in northern Australia (beyond the range of the fox), found that a reintroduced native rodent, Rattus villosissimus, persisted in study sites at which cats were excluded but was rapidly eliminated from paired sites to which cats had access (75). In complementary studies examining the diet of feral cats and red foxes in many parts of Australia, a high rate of predation on native mammal species has been demonstrated, often with particular selectivity to the species groups of native mammals exhibiting decline (76,77).…”

Effect of small-scale woodland clearing and thinning on vertebrate fauna in a largely intact tropical savanna mosaic

“…The low richness and trap success rate of mammals recorded in the present survey are typical of the region and within Queensland rangelands (Kutt 2012). This is a function of both the long-term changes in the vertebrate fauna of rangelands (Eyre et al 2011) and a general, insidious, but poorly defined problem of recent decline in mammal abundance across many parts of northern Australia (Woinarski et al 2011).…”