June 3,2016
HOW DO FERAL CATS EFFECT THE AUSTRALIAN NATIVE FAUNA?
The impact that feral cats can have on the Australian native wildlife can be estimated by calculating the energy requirements (food, living environment, population) of the average adult cat (Broadman, 2016). However, the reliability of those estimates is uncertain as the entire prey is not always eaten, especially in areas where there are abundantly different kinds of prey, and the energy requirements of feral cats are assumed to change considerably depending on the environment (AWC, 2012-2013). A single feral cat can kill potentially 4 or 5 native animals and over a year, an average of about 1400 native animals that are killed by a single feral cat (Cameron, 2016).
In mainland Australia, feral cats occur in almost every types of habitat including deserts, forests and grasslands (AWC, 2012-2013). Their diets contain numerous of animal species, which then lead to an extermination in a large number of native fauna (Dickman, 1996). From a report of Chris R. Dickman, in temperate forest and suburban habitats, the common ringtail possum P. peregrinus (an Australian marsupial) is consistently highly represented in the diets of feral cats, in wet-dry tropical and arid habitats where rabbits do not occur, native rodents (gnawing mammals) such as black rats, house mouse and five-lined palm squirrels become an important part of the diet of feral cats (Dickman, 1996). In general, birds are the most highly represented prey in temperate forest, urban and suburban habitats, as well as in some localities in arid Australia (Milman, 2015). Accordingly, reptiles, amphibians and especially mammals are mostly appear in feral cats’ diets (Broadman, 2016). Therefore, the most effective way to quantify the impacts of feral cats will be to remove cats from specified areas and keep the responses of native species which are assumed to be at risk under observation. It has shown the serious impact of feral cats to native fauna in mainland Australia (Sarah A. May et al, 1996). On islands such as Macquarie, Raoul and Stewart, feral cat diets are likely similar to those in mainland areas of Australia, but they are mostly comprised of rabbits and rats (Dickman, 1996). The main category of food is small marsupials, but on some islands are amphibians, large reptiles or bats (Calver et al, 2011).However, the range of food categories on islands isn’t as abundant as in mainland. Feral cats have affected the population of small mammals, they have been implicated in the decline and extinction of 22 mammal’s species in the last 50 years (Dorherty, 2015). Considering the number of island species whose extinctions have been caused by feral cats, it is remarkable that there have been so few document indicated the complete destruction of feral cats to the Australian native fauna (Conservation, 2015). There was no negative environmental impacts of feral cats to Australia received (Dorherty, 2015). There is no conclusive evidence to support the notion that feral cats have resulted in big changes to the abundance of native mammals (Cameron, 2016). However, feral cats have been believed that they have been involving in the decline and extinction of 22 mammals’ species (Dorherty, 2015). |