The global ecological menace of pet cats (and how to stop them pissing on yourΒ car)

In this unusual Caturday video special: this clever man took action against hormonal cats that were pissing on everything in his possession, from his front door to his car windscreen

by GrrlScientist for The Guardian | @GrrlScientist

(Graphic via WikiHow / Creative CommonsΒ license)

For some inexplicable reason, people think it is okay to allow their domestic house cats to roam outdoors. I’ve never understood this, especially since in most civilised nations, we don’t allow any other companion pets or domestic animals to roam freely. Further, house cats take a terrible toll on native wildlife and hybridise with their wild relatives (in Scotland), their fΓ¦ces are revoltingly gross and pose a health hazard to humans and other animals, and, unvaccinated, house cats can act as a vector for rabies and for a number of deadly and often incurable feline diseases, such as feline leukΓ¦mia.

In view of these very real problems, it might seem that one of the many issues associated with free-roaming catsβ€Šβ€”β€Šscent markingβ€Šβ€”β€Šis a minor offence. But at least one person disagrees: offended by hormonal cats pissing on everything in his possession, from his front door to his car windscreen, this clever man took action.

But house cats cause much more serious and lasting damage than pissing on a few car tyres. In fact, feral and free-roaming domestic house cats are recognised as one of the world’s most devastating invasive species due to their ability to live in a wide variety of habitats, including forests, grasslands, tundra, coastal areas, agricultural land, scrublands, urban areas and wetlands. They even are found on small oceanic islands where there are no human inhabitants.

Feral cat with cockatoo, mounted specimen. (CC BY-NC-SA)

In the UK, the domestic house cat population increases by half a million cats annually and their overall abundance far exceeds the natural carrying capacity for any area where they live: because house cats are fed and cared for by humans (even when only sporadically or accidentally), their numbers are independent of their prey’s population dynamics. This means that feral and free-roaming cats will nearly always find something to eat, whether provided by humans, either directly (in a food bowl), or indirectly (discarded food), or by massacring native wildlife. As a result, the population densities of house cats can be as high as 2000 individuals per km (ref).

European robin (Erithacus rubecula) is a ground-nesting bird that is commonly killed by feral and free-roaming house cats. (Credit: bugmonkey / CC BY-NCΒ 2.0)

Outside of 33 documented cases where domestic house cats caused the extinction of particular species, their predatory effects on birds and native wildlife are surprisingly undocumented. But some work is being done on this issue. For example, scientists have found that the average feral and free-roaming house cat’s diet consists mainly of birds, with ground-nesting birds being particularly vulnerable. Thirty percent or more of house sparrow (ref), robin and dunnock (ref) mortality is due to domestic house cats. Because house cats are recreational hunters (ref)β€Šβ€”β€Šrather like humansβ€Šβ€”β€Ševen well-fed pets that are allowed to periodically roam freely can hunt and kill small animals, mainly small mammals, but also birds, amphibians, reptiles, fish and invertebrates (ref & ref), which they then do not consume.


Originally published at The Guardian on 7 May 2011.