A Biological Invasion

By Linda & Dmitry Cherkassky

Photo credit Scotty Lisenbe

There are aliens among us.  (No, not from outer space).  They sleep in our beds, rub against our legs, and often have something called ‘the zoomies’ upon exiting the litter box.  They are bizarre and beguiling, but we love them anyway.

Felis catus, the domestic cat, is an alien or introduced invasive species.  Domestic cats are not indigenous to any ecosystem and are a serious threat to biodiversity.  Habitat loss and climate change are the primary challenges for native wildlife, but domestic cats are the leading direct anthropogenic cause of wild bird and small mammal mortality in North America.

Indeed wonderful as companion animals, when free-ranging outdoors they can wreak havoc on the environment.  A single cat can extirpate fauna from a local area.  Domestic cats are no less motivated to hunt even when well-fed, thus preventing access to wildlife is essential.  When our pet cats are permitted to roam or when individuals sustain dense aggregations of homeless cats outdoors, wildlife is adversely affected through predation, the transmission of diseases, and competition for resources.  Human health is also at risk.  Domestic cats transmit myriad zoonotic diseases.  They are the leading domestic animal carrier of rabies and the definitive host for the protozoan parasite that causes Toxoplasmosis.

An invasive species is defined as a non-native organism whose introduction causes or is likely to cause economic or environmental harm or harm to human health.  Currently, there is national and international legislation that could be applied to domestic cats and their impact on the environment yet consistent implementation has been lacking.  Designating the domestic cat as an invasive species will enable decision-makers to enact and implement practical and effective policies that properly manage free-roaming cats.  This is the crux of a recent publication which we had the privilege of co-authoring… A science-based policy for managing free-roaming cats.

The authors advocate for scientifically supportable local, state and federal policies that focus on responsible pet ownership and sound management of free-roaming cats.  This will aid in the conservation of protected species resulting in more sustainable ecosystems, improve the welfare of domestic cats, and create healthier communities.

In 2018, the Western Governors’ Association listed Felis domesticus as #13 on the list of the Top 25 Terrestrial Invasive Species in the West.  A few states (including New Jersey) and the Polish Academy of Sciences already list the domestic cat as an invasive species.  Not to mention, there is now a set of recommendations for addressing free-ranging cats on lands managed for native wildlife.  The next step is for more agencies and jurisdictions to recognize the domestic cat as a non-native invasive species.  More than a decade ago, the International Union for Conservation of Nature (IUCN) listed the domestic cat as one of the world’s worst non-native invasive species.  The time has come to end politically appealing ‘programs’ that in essence promote the outdoor hoarding of homeless cats.

In the United States, for every outdoor cat, 21 to 55 wild birds will perish annually.  This does not include many more small mammals or reptiles, amphibians and invertebrates.  Good intentions do not necessarily produce good outcomes.  The misguided compassion in attempting to ‘save’ cats from the sad yet humane duty of euthanasia of unadoptable cats by subjecting them to life and death on the streets through the unsound and specious practice of Trap-Neuter-Return (TNR) results in the suffering of those cats and countless wild animals upon which those cats prey.

Furthermore, the feeding that accompanies TNR has significant unintended consequences.  Native wild mammals, including Rabies Vector Species that get a whiff of the bounty of cat food littered on the ground, dine at feeding stations.  They forage less for their own natural food sources and become habituated to humans.  This increases risks to public health.  Inevitably there is human-wildlife conflict and the species that actually belong in our environment are often destroyed.

As an organization involved in wildlife education, we abide by the National Wildlife Rehabilitators Association Code of Ethics.  We work on the basis of sound ecological principles, incorporating appropriate conservation ethics and an attitude of stewardship.  We promote a responsible concern for living beings and the welfare of the environment.  TNR is the antithesis of doing what is right for the planet and its inhabitants.

Love cats, cuddle them, pamper them, but for the sake of wildlife (and human health) do not let them roam and do not harbor and feed ‘colonies’ of them outdoors.  Spring has arrived.  Migratory birds are returning and breeding season has begun.  Now is the time to transition cats to indoor living or enjoying the outdoors safely and responsibly through leash training and/or catios.

Still not convinced?  Think of things this way… If you wouldn’t blast a songbird out of a tree, don’t let the cat out.  When you open the door, you have pulled the trigger.  The cat is the bullet.  It is that simple.

Photo Credit Debi Love Shearwater