Feral cats... the only domestic animals that can cause an all out war between Audubon Society members and animal welfare activists

So what is a feral cat?

A feral cat is a domestic cat that has grown up outdoors without any human contact and has reverted back to a wild-like state. Unlike stray cats, feral cats want nothing to do with humans and act more like wild animals than your average house cats. These cats then reproduce at exponential rates in wild ecosystems and can have very negative effects on prey species and predators that they compete with for resources.

What can be done about them?

Several management methods are used to stop the out of control breeding that can very quickly lead  from several cats to several dozen. The two most common methods are euthanasia and TNR but the preferred method of choice all depends on who you talk to. Euthanasia is a method in which the cats are humanely trapped and brought to a licensed veterinarian to be euthanized, the same way your pet cat would be. The other method, TNR, stands for trap neuter return, and is a little more of an involved process. In TNR, cats are trapped and brought to a veterinarian, where they are neutered, vaccinated, and given an ear tip before being re-released to the area in which they were trapped. An ear tip is used as an indicator that the cat was already neutered so if the cat is trapped again, they can release it so it doesn't have to endure another trip to the vet.

Which method of control is better?

This is where the debate comes into play. Most conservationists share the opinion that euthanasia is the preferred management method. This method more quickly reduces the pressures the cats cause on the wild ecosystems they inhabit. Feral cats can cause many problems for both prey and other predators they compete with. For prey animals, these cats are lethal, especially for species of small birds and mammals. These cats are the largest contributor to small bird fatalities and kill four times as many birds as building collisions. The cats can also compete with local predators as well by depleting prey species that these predators survive on, as well as out-compete them for space and other resources. Conservationists also argue that TNR takes too long to wipe out a population of cats, because the cats can live for many years after TNR, and can continue to negatively effect the areas they inhabit.
 However, animal activist groups and welfare supporters argue that the euthanasia method is unethical for the cats. Activists also argue that the method is ineffective at reducing populations because the vacuum effect occurs. This means that when cats are removed from an area, more cats migrate in to re inhabit the area.
In reality, both methods are effective at reducing feral cat populations over time. Whichever management method you support, the effects these cats have are obvious, and doing nothing to stop it is not an option.