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Cats are a leading cause of bird death in Canada

03/10/2013 09:30:05

Feral and owned outdoor cats in the U.S. are responsible for the deaths of 1.4–3.7 billion birds in the US alone. Photo credit ABC

Domestic and feral cats are a major cause of bird mortality
October 2013. A new study from the government of Canada that looked at more than 25 human-caused sources of bird mortality has found that domestic cats, both feral and owned, are the leading lethal threat to birds in the country.

200 million birds killed by cats in Canada alone
The study found that the median estimate of cat-caused mortality-almost 200 million bird deaths per year-was about six times greater than the next leading mortality estimate of about 32 million attributed to car collisions. The third-leading cause was collisions with buildings or homes, with a rate of about 22 million bird deaths per year.

"We synthesized estimates of the magnitude of human-related mortality in Canada from major industrial sectors and non-industrial or public activities that we believe kill substantial numbers of birds," the report says. Some of the bird-mortality sources in addition to the top three included: transmission line collisions, wind energy, mining, forestry, and pesticides used in agriculture.

A threat to Scottish wildcats

A new action plan to reverse the decline of the Scottish wildcat within six years has been launched by Scottish Environment Minister Paul Wheelhouse.

The aim is to conserve Scottish wildcats by reducing the chances of cross breeding with domestic and feral cats and by lowering the risk to wildcats from feline diseases.

The scale of coordinating trapping, neutering and vaccination of feral cats and hybrids has not previously been attempted on such a scale in Scotland.

Why not euthanize the feral cats?
Wildlife Extra questions why they are going to elaborate lengths of trapping, neutering and vaccinating these feral cats before returning them to the wild? Returning them to the wild where they still pose a threat to other native wildlife and will compete with wildcats for limited resources sounds perverse. WE can only imagine that they are running scared of the cat protection lobby?
"A wealth of scientific studies in the United States have sounded the alarm about bird and other wildlife mortality from cats. Those studies have also voiced strong concerns about potential human health impacts. This Canadian national study continues a warning trend about this growing invasive species disaster that is at our doorstep in the form of outdoor cats," said Grant Sizemore, Cats Indoors Program Manager for American Bird Conservancy, a leading bird conservation group in the United States.

400 species - Several billion birds

The Canadian study says that several billion birds from over 400 species breed each year in Canada in a wide variety of habitats, but shorebirds, grassland birds, and aerial insectivores in particular have experienced rapid declines. Some of those declines are attributed to human-driven habitat change and mortality across North America over the past 40 years.

Some species are highly vulnerable
The study highlights the susceptibility of particular bird groups to certain mortality sources, such as the vulnerability of long-distance or nocturnal migrating birds to collisions with towers and buildings or of auks to be killed as bycatch in fisheries' gillnets.

Non-native invasive species
Sizemore said that domestic cats are a non-native species in North America and are efficient, instinctive predators. Research by scientists from the Smithsonian Conservation Biology Institute and the U.S. Fish and Wildlife Service recently estimated that 114-164 million feral and owned outdoor cats in the U.S. are responsible for the deaths of 1.4-3.7 billion birds and 6.9-20.7 billion mammals every year. Even the mere presence of cats in the environment has been shown to reduce bird reproductive output and survivorship.

"Cats on the streets lead harsh and traumatic lives," said Sizemore. The American Veterinary Medical Association (AVMA) has estimated that feral cats have an average lifespan of only two years, whereas owned cats average 10 years. Reasons for this reduced life expectancy include attacks by dogs and other feral cats, predation, being hit by cars, ingestion of poison, disease, and more.

Feral cats cause wildlife predation & zoonotic disease transmission
Although some "humane" organizations seek to maintain cats outdoors, numerous state agencies, professional societies, and non-profit organizations understand that doing so is detrimental to cats, wildlife, and people. For example, the AVMA's Committee on Environmental Issues has stated that "managed cat colonies do not solve the problems of cat overpopulation and suffering, wildlife predation, or zoonotic disease transmission."

Eliminate feral cat colonies
Consequently, the committee "strongly supports and encourages humane elimination of feral cat colonies" and "opposes passage of local or state ordinances that legalize the maintenance of managed [commonly called Trap, Neuter, Release, or TNR] cat colonies."

People for the Ethical Treatment of Animals (PETA) also vigorously opposes TNR, taking the position that it is inhumane for the cats as well as the wildlife they hunt, injure, and/or kill.

Rabies & toxoplasmosis
According to scientists from the Centers for Disease Control and Prevention, cats are consistently the number-one carrier of rabies among domestic animals and pose a "disproportionate risk for potential human exposure." Domestic cats are also the necessary host for the parasite that causes toxoplasmosis to complete its life cycle; each infected cat may shed hundreds of millions of the infectious parasite in its faeces. In people, toxoplasmosis has been linked to schizophrenia, Alzheimer's disease, obsessive-compulsive disorder, and other neurodegenerative diseases. It can also cause sudden abortion and foetal abnormalities in pregnant mothers.

Read the comments about this article and leave your own comment

Irresponsible and ill-conceived comment

Every time a study is published about anything negative on TNR people like yourself come up with comments like you just did. What is irresponsible is dumping these cats on the streets. TNR advocates have no concern for wild life, humans, and most of all the cats. Do you know why the average life span for these cats is 2 to 3 years? Because even though you may bring them food there is no real care for them. They get sick or injured and left to die a slow death with no one doing anything for them because that is what you call the natural way of death for these cats. You feel that euthanizing them in shelters is inhumane, I think it is inhumane to let them suffer and die but with plenty of food. Then there are the people who either are tired of dealing with them on their property or the people who just like to torment animals and kill them in horrible ways.
Even though you vaccinate them one time when spayed/neutered you never vaccinate them again. More and more news stories are popping up about rabies infected cat colonies because we all know who likes to come for dinner besides the cats, raccoons and skunks. How irresponsible is that for a community. Not only are we as humans at risk but our pets are also.
Maybe it is time to think of a different way of dealing with these cats.

Posted by: Christine | 13 Oct 2013 03:22:23


the main problem with domestic cats, is that they serve no real purpose in the natural world. if people wish to keep this animals as companions ? they should be kept indoors at all times. im sure show cat folk dont allow thier cats to wander the streets and parks ?. im sure by now there is sufficient evidence from all around the world that cats that have gone feral as well as those allowed the freedom to roam , have a massive impact on wildlife. not just birds of course, but bats, frogs, butterflies,mice, etc. cats are fed and housed by humans, they have no need to kill wildlife, but as long as they are allowed outdoors, thats what happens. as for feral cats, or deserted cats ? they carry disease. and cannot have a very happy existence anyway.

Posted by: dee donworth | 05 Oct 2013 10:14:51

Feral Cats are not natural predators.

Ill-conceived is the proper way to describe the response from Freya rather than the article itself.
If there are "innocent animals" there must be "guilty" animals. Which might they be?
Does she oppose the elimination of rats or pigs from ,say, New Zealand islands?
Should we protect the House Mouse, Headlouse, Woodworm or is just the pussycat to be treated with special consideration?

Posted by: Dermot McCabe | 04 Oct 2013 21:09:23


Thank you WE for highlighting how the introduction of EXOTIC predators are detrimental to an ecological system that has not evolved with them. As a Veterinarian and wildlife researcher, I have seen many feral cats suffering from several diseases and even traumatic deaths from roaming outdoors where they clearly do not belong anymore. Great article and I am now sharing this post with fellow wildlife researchers.

I'm attaching phrases from peer-reviewed articles:

"Cats have contributed to declines and extinctions of birds worldwide and are one of the most important drivers of global bird extinctions. Cats also have impacts on birds through competition with native predators such as raptors, and through the harboring and transmission of zoonotic and other diseases to birds and other wildlife." - Dauphine and Cooper, 2009.

"...we need to move away from the prevailing view that depredation of individual wildlife species does not matter as long as their populations are intact. If we are to consider cats from an individualistic viewpoint, then the same argument must be made for wild animals." Lepczyk et al. 2010. Conservation Biology.

Posted by: Veeve G | 04 Oct 2013 15:46:25

Irresponsible and ill-conceived article

This is an extraordinarily irresponsible and ill-conceived article. Demonising an animal for acting upon their natural instincts is both immoral and dangerous for the animal in question. Feral cat colonies exist due to human negligence and killing / euthanizing them is an inhumane and unfair response, suggesting otherwise encourages people to dislike them to the point of hunting them, which inevitably leads to slow and painful deaths for innocent animals.

TNR is a far better way to gradually eradicate feral cat colonies without killing them, they have a right to live whether or not you (or people in general) appreciate them as an animal. Just like demonising badgers for carrying TB in the UK (and thus attempting to cull the majority of them), you cannot apportion blame for the death of one animal on another, they are merely acting out their instinctive behaviour – (and in the case of bovine TB and badgers, blame is based on flawed evidence).

Killing one animal because they kill another is hypocritical and ridiculous. I am shocked that Wildlife Extra would write an article like this, we should not advocate the killing of any wild or domestic life and we certainly should not demonise a species. Cats prey on birds and rodents, so do many other animals, should we kill every predator? We shouldn't have a right to decide that kind of thing.

Posted by: Freya | 04 Oct 2013 12:23:00

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