June 4, 2016
WHICH PARTS OF THE AUSTRALIAN ENVIRONMENT DO FERAL CATS AFFECT THE MOST?
Feral cats can be easily found in all habitat around the Northern Territory, and it is recognised as one of the top three key areas in Australia where native species are in a significant threat from the cats (Crompton, 2016). Researchers believe that the Northern Territory's feral cat population exceeds 100,000 and this is the reason for the annual killing of more than 36.5 million small native animals (Barratt, 1997). More than 30 percent of the Northern Territory's desert living small mammal species have been wiped out with several bird species (Kymlicka et al, 2014). Feral cats appear to have involved in the extinctions of more than 20 pieces of native animals (Sharp, 2002). Feral cats have changed themselves surprisingly well fitting to the Australian bushlands to become one of this country's most efficient and skilful hunters in the wild (Johnson et al, 2015). Most species of terrestrial small mammals have been declining, and there is evidence that this is due to the predation by feral cats (Sarah A. May et al, 1996).
The impact of feral cats on the small vertebrate fauna of Western Australia was explored using diet analysis (Cox, 2015). The diets of feral and semi-feral cats were similar in the diversity of prey species, but different in the frequency of some food categories (Danniel et al, 1999). Native rodents, birds and reptiles occurred more frequently and were ranked higher in the diet of feral cats, and food scraps occurred more frequently in the diet of semi-feral cats (Danniel et al, 1999). Accordingly, cats are more likely to have an impact on small vertebrates and that the control of cats could lead to recoveries in the populations of native rodents, birds and reptiles.
Feral cats are present in large numbers in central Australia, across most of the region and are having significant impacts on native mammals (including threatened species such as bilbies, black-footed rock-wallabies and mulgara), birds and reptiles (including the nationally threatened great desert skink and Slater’s skink) (Council, n.d). Recent research has indicated that predation by feral cats may have been important. Predation by feral cats was the primary factor involved in the recent failure of a reintroduce program for the hare-wallaby in central Australia (G. P. Edwards et al, 1997). In other hand, feral cats is not only impact on native animals, but also spread disease, for example “Toxoplasma gondii” (a zoonotic infection), which can have fatal consequences for wildlife animals and some livestock (Lateline ABC et al, 2014). Because of the cross-over between feral, stray and domestic cats, the risks of disease spreading and the possibility for inter-breeding are significant high (Calver et al, 2011).