One of the more surprising invasive species, now found across the world thanks to mankind, is the domestic cat! Whether these moggies are pets left to roam free, or have established themselves as feral population, both cause unimaginable damage to various species around the globe. Domestic cats have no native range, and they are listed among the 100 worst non-native invasive species in the world, by the International Union for Conservation of Nature (IUCN). In 2013, a study conducted in the US estimated that domestic cats, both owned and feral, killed between 1.3–4.0 billion birds and 6.3–22.3 billion mammals each year. As well as the direct effects of hunting, cats can act as vectors for multiple diseases, including those that can be spread to humans such as rabies.
The domestic cat is, of course, a beloved pet, but most people seem to be oblivious to the ecological damage their cat has the potential to inflict. These effects are more notably seen on islands, with statistics recorded by the IUCN Red List indicating that cats have caused or been implemented in the extinctions of 33 modern birds, mammals, and reptiles. Here in the UK, the very rare and endemic Scottish wild cat is at risk of imminent extinction due to hybridisation from feral cats, and the transmission of disease. There have been isolated incidents around the world of single cats killing large amounts of wildlife, such as a case from Ohakune, New Zealand where in a week one cat killed a total of 102 bats. This is based purely on the number of bats that were found dead; we all know cats like to play with their food, thus the real number is likely much higher. All of this has sounded pretty negative so far, but I am not against owning cats, nor do I hate them. I think now is the time to step up and to become responsible for the actions of our pets in order to prevent further damage to the ecosystems into which we have transplanted them.
The main reason they are such a threat is that the animals that they hunt are not used to predators (especially on islands); and so, cats can unfortunately lead to their extinction. I am sure if you own a cat, it may have once bought you unwanted gifts in the past – in the form of dead mice or birds. If you want to help prevent local wildlife in your neck of the woods from declining, try to keep your cats in doors and neuter/spay them. Cats are prolific breeders, with feral populations quickly growing due to their young age of sexual maturity and the large numbers of litter a cat can have each year. So next time Tigger is out playing in the garden, just think of the unseen damage that your beloved pet may actually be responsible for.