Two months ago I wrote about finding a family of cats along the trail in the Galápagos Islands. The beautiful kittens would grow up to be murderers of vulnerable animals such as the rare species of hawk unique to the Galápagos. It was with mixed feelings that I learned that a ranger would be dispatched with dogs to obliterate this invasive family.
Can these lovable pets be a hazard here in the USA? Do they cause any problems with wildlife in our backyards?
The answer, unfortunately, is that cats allowed outside can be a serious problem, causing the deaths of billions of small animals.
Once, eating dinner as a kid, Cookie (our family’s cat) proudly joined us with her own meal in her mouth—a robin that she had just caught and killed. Until then we had no idea that she had been hunting in our backyard.
Cookie was not unique. Recent reviews suggest that cats kill huge numbers of small animals. In some cases we benefit from cats’ lethal effect, such as barn cats killing mice and rats. Unfortunately they are also responsible for the slaughter of many birds.
Fortunately not all cats are killers. Indoor cats aren’t given the opportunity to commit mayhem. And some pet cats that go outside leave little critters alone. Feral cats, who survive by tooth and claw, are the most destructive. However, free ranging domestic cats are estimated to kill over 2 billion birds every year in the USA.
Islands are where cats have caused the most trouble. Many unique species have developed in the isolation of islands; Darwin’s finches are a famous example. They are all unique to the Galápagos since they evolved in that remote cluster of islands.
Pirates and other sailors brought cats to the Galápagos over 300 years ago. These four-legged intruders caused a rapid decline in the numbers of birds—and of the unique marine iguanas. A concerted effort to eradicate cats has been successful on some of the islands, with subsequent increases in members of endemic species that live nowhere else. Fortunately, the Galápagos hawk is one of those that is bouncing back due to cat control.
Things didn’t work out so well in the Hawaiian Islands. The black-faced honeycreeper (Po’o-uli) is critically endangered. There are many reasons some birds aren’t doing well in Hawaii; avian malaria, destruction of habitat and killing by predators (including cats) are all serious threats. Of the 33 species of the small, stunning honeycreepers that have existed recently, 12 are now extinct and 9 are critically endangered or probably extinct. Only two honeycreeper species seem safe from extermination.
A recent study of killing by cats divided Felis catus into three categories: those that always stay inside, those pets that have homes but spend time outside, and those that live outside. The latter category includes barn cats whose purpose and livelihood are controlling rodents. It also includes feral cats that have no attachment to humans.
The undomesticated populations are responsible for most, but not all, of the killing. It is estimated that they do away with two to three billion birds each year in the USA, and up to 20 billion small mammals, reptiles and amphibians. They certainly have earned their place on the list of the world’s most destructive exotic species! We know that birds also die from collisions with windows and windmills, but cats destroy a much larger number.
Spying on domestic cats’ habits with cameras attached to their necks suggests that innocent-appearing Fluffy may actually be a serial killer. Indeed, indoor pet cats with outdoor access may kill a half billion birds a year in the USA! The story of one pet is shown at: www.pbs.org/pov/catcam/full.php#.UTSpLBlrciJ For more evidence that pet cats might be a closet killers check out “Crittercam†videos at http://www.kittycams.uga.edu/photovideo.html
Animal rights folks focus on protecting cats, but seem blind to the mayhem that cats cause. Feral cats number perhaps 50 million in the USA. Animal rights people have developed two types of programs in an attempt to control them. The Trap-Neuter-Return policy seems most humane because it doesn’t kill these wild creatures. Unfortunately TNR programs allow cats to return to their accustomed lethal pursuits. Euthanizing wild cats is better than TNR since it prevents massacre as well as reproduction.
As loveable as cats are, they can be killers. Devices to make it more difficult for cats to kill wildlife are available; locally, For the Birds carries a couple. It is best to keep cats inside for wildlife’s sake!
© Richard Grossman MD, 2013
Category: Environment
Related to environmental issues.
Stick to Humor, Dr. Black
“…the first essential component of social justice is adequate food for all mankind.â€
Norman Borlaug, in his 1970 Nobel Peace Prize acceptance speech
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           I used to love to listen to Baxter Black on the radio. I admired his sense of humor and his human insight. Then I read an article he wrote.
“What is sustainable ag?†appeared in the March, 2013 issue of Western Farmer-Stockman. I am writing this as a response to my friend Al, who clipped the article for me. Al is a wise man and an experienced farmer. He wrote: “I thought this was a good article on sustainable agriculture. I hope you find it interesting.â€
Indeed, it is interesting—not for what it contains, but for what Dr. Black left out. First, let me summarize the article.
Dr. Black writes that that most agriculturalists think that “sustainable farming†is a joke, and derides those who want to return to pre1950 farming methods. He makes fun of “hobby farmers†who have a garden and a few animals since they don’t produce enough food to feed their families for even two weeks.
Black then rightly recaps the history after World War II, when world population soared and people worried about food shortages. Megacorporations and scientists were able to increase food production remarkably, despite the creep of cities taking over productive ag land. He doesn’t mention the “green revolution†of Dr. Norman Borlaug and others, which is credited with saving over a billion lives by developing highly productive strains of crops.
This modern, industrial model of agriculture is sustainable according to Black, because it can sustain so many people. Great grandpa’s old-fashioned ways of producing food are laughable in today’s context, he writes. He would prefer the term “subsistence-level farmingâ€.
Although I understand Al’s and Black’s viewpoint, I cannot agree. My concern is that, along with its good, the “green revolution†has had several dreadful unintended consequences.
Growing highly productive plants and animals requires the use of many chemicals that are made from limited resources, and are toxic. The chemicals include fertilizers, insecticides, fungicides and herbicides. They are all derived from fossil fuels, and all transported with fossil fuel. Unfortunately, supplies of carbon-based fuels are limited. We have probably already maximized the production of petroleum and soon will see its decline—and a rapid increase in prices.
We are starting to realize the subtle toxicity of many of the agricultural chemicals. The wonder insecticide of my childhood, DDT (which I was told was entirely safe) turned out to be an ecological disaster and now is banned in many countries. An amazing group of insecticides, neonicatinoids, is probably responsible for the die-off of our honeybees—colony collapse disorder. Since bees pollinate so many crops, this is an agricultural disaster.
We now realize that many agricultural chemicals have endocrine effects, even in minuscule concentrations. Just a pinch in all the water in an Olympic swimming pool can cause harm! Insecticide residues may decrease sperm counts. One common agrichemical, atrazine, has been shown to cause feminization of male frogs and has been implicated in reproductive cancers.
The seeds of highly productive plant strains must be bought from corporations that control their prices. In the past, seed grain was carefully preserved from the prior crop, but now farmers need cash—or credit—in order to buy seeds. This expense, along with the cost of the chemicals, has broken many farmers. In a good year they can make a living, but in a bad year their suicide rate climbs.
Finally, modern agriculture depletes our soil. The use of chemicals exhausts many components that help plants grow.
There is a subtle chicken-and-egg situation here. Modern agriculture has increased food supply, which allowed our population to swell. Borlaug outwitted Malthus, who predicted that human population would be limited by starvation from lack of food.
Here is the quandary: does modern agriculture only provide a short-term gain? As we deplete petroleum and as crop growing conditions worsen from climate change and drought, can the amazing technology of modern agriculture be sustained? Indeed, some scientists have a terrible vision of severe food shortages with bloodshed and more deaths than Borlaug’s green revolution saved.
In his Nobel Prize speech quoted above, Borlaug also said: ““Most people still fail to comprehend the magnitude and menace of the ‘Population Monster’.†Hopefully Herald readers are better informed than most. But only time will tell if Dr. Black is correct about sustainable agriculture, or if he should go back to being a humorist.
© Richard Grossman MD, 2013