The ranger stood on the dirt road, facing south, and the rest of us, scattered about the parked safari truck, facing north and paying close attention to what she was saying. The sun was slipping quickly below the red sand dunes to our west, and the day’s warm breeze was rapidly changing to a chill wind. She talked about what we might see after we remounted the safari truck, which we had just driven out of the campground at the southern end of Kgalgadi Transfrontier Park, where we were staying in the South African camp, just across from the Botswana camp. This would be a night drive, cold, dark, uncomfortable seats, loud engine in the giant 26-seater truck, scanning the brush and the roadside with three or four strong spotlights wrangled by volunteers among the nature-loving tourists, and of course, the headlights of the truck. But for now the sun was still up and if anything interesting came along we’d see it just fine in the dusk.
And, of course, something interesting came along. Just as the ranger was telling us that we might see wild cats – well, not wild cats, but rather, Wildcats, the wild version of the domestic cat, Felis silvestris lybica, one of those cats popped its head out of the brush about 50 feet beyond her. As she continued her monologue about these cats, the Wildcat cautiously walked in our direction, never taking its eyes off of us, stiff-legged, ears motionless, striped like a standard “tiger” domestic cat but entirely in grays. The most interesting thing about this cat was lack of kitty-cat-ness. It was not a kitty cat, even though all of its relatives in the Americas were. It was deadly serious, intense looking, nothing like a kitty cat at all. And just as the ranger finished her monologue with “… so if we’re lucky, we’ll see one of those cats” the person standing next to me intoned, in a mimicking fake british-sounding accent to match the ranger’s South African dialect, “You mean like that one, there?” and all of us pointed simultaneously to the wildcat now about 10 feet behind her.
She turned, looked, and by the expression on her face I guessed she was thinking “Goodness, I’m glad that was not a lion.”
That was a wild cat, a wild Wildcat, the cat that lives in the wild because that is where it is from and where it belongs, at the southern end of its pan-African range that extended at one time well into Europe and Asia. Read what you want about the origin of domestic cats; the genetic evidence is not properly sampled. The majority of wildcats live today in Africa, and virtually none of them have provided the DNA from which supposed histories of domestication have been constructed by researchers. The point is, Wildcat, the very close cousin to, physically identical to a domestic kitty cat but with a kick-ass attitude, is these days as African a beast as is the Lion (which once also lived across Europe and Africa) or the Okapi (which did not).
But they don’t live in North America. Unless we put them there.
I once knew a guy who kept and raised cats. Have you ever seen the Dryfus Lion? The one that walks around Wall Street and somehow makes you want to invest in the stock market? That was one of his cats. He also had tigers, cougars, and some other animals. I new him because we enlisted his Dryfus Lion and one of his tigers to carry out experiments with bones (this is something archaeologists do). One day he said, of domestic cats, “Yeah, if those particular cats were scaled up to lion size but with the same attitude, we’d all be cat food.” And I think he was speaking only of our American Kitties not the Wildcat of Africa. Which would be even worse.
I find it astonishing that people argue of whether feral cats are bad for birds in North America. The plethora of approaches to the feral Cat problem is not an outcome of a diversity of great ideas; it is the ugly chimera of inappropriate compromise among biased and often poorly informed stakeholders.
Let me tell you this: They are. And for rodents and reptiles as well. This almost certainly can be argued to be true just on the basis of logic, because feral Cats are proficient hunters and are entirely out of ecological place. There is no native cat smaller than a Bobcat here, and Bobcats are considerably larger than Kitties. Generally speaking, carnivores divide the world up by size. This is approximated by the size of the animal, but really, this has to be adjusted for depending on modality of killing. So you can describe the carnivore landscape for Cats by plotting the canine length, and you’ll see that male and female versions of the three or four Cats in a region take up all of the size-space for Cats, and correspondingly, all of the Cat-accessible prey. Smaller and larger animals (if there are any) are taken by other creatures. You can make a similar map for the small carnivores, the Mustelids, such as minks, ermines, otters, etc. but instead of using canine height you use carnasial length (the carnasial is the tooth the weasels use to rip the flesh of their prey). The male and female versions of all the Mustilid in a region will not overlap much in carnasial length. In some regions of the world, the carnivore landscape is taken up by many different cats at the middle and larger range, and by things like civets and mongoose at the smaller end. In North America, you’ve got Bears at the large end, Cats in the middle, and at the smaller end, the Mustilids.
There is not a wild cat, such as the Wildcat, in North America, at that lower end of the size range for cats. That part of the carnivore landscape is taken by other animals. Dogs are similarly dispersed across size ranges, with Foxes, Coyotes, and Wolves taking prey across different parts of the size range.
And for thousands of years the lizards, rodents, and birds of North America adapted to Fishers, Badgers, Wolverines, Ermines, etc. among the Mustilids, and Coyotes and to a lesser extent Foxes. When you throw the feral Cat in there, not only do they push out the indigenous wild carnivores, but they are hunting animals that are not quite adapted to avoiding them as well as they may be to avoiding other animals.
Add the effects of climate change to the mix, and things are likely to be even worse.
How many wild birds are eaten by either feral Cats or “outdoor Cats?” Many. Probably too many. The numbers are all over the map. The number of birds, and other animals, killed by feral Cats is probably large, but it either varies a great deal from place to place, or the estimates are so inaccurate that they, the estimates themselves, vary a great deal from place to place. We do know this: In areas where feral cat populations exist, they are often well established. This means that they eat a lot of rodents and birds. Also, feral Cats on islands seem to be a serious problem, causing the extirpation of some indigenous species. This demonstrates that the Cats are damaging, but we may see less damage in non-island situations because there is more edge, more room for the different parts of the system to expand into now and then. A hungry feral Cat in Minnesota goes and finds new prey in an area it previously had not explored, leaving the last few of one or another bird species alone for a while. On an island, the feral Cat eats all of those birds.
An abstract from a recent paper in Nature:
Anthropogenic threats, such as collisions with man-made structures, vehicles, poisoning and predation by domestic pets, combine to kill billions of wildlife annually. Free-ranging domestic cats have been introduced globally and have contributed to multiple wildlife extinctions on islands. The magnitude of mortality they cause in mainland areas remains speculative, with large-scale estimates based on non-systematic analyses and little consideration of scientific data. Here we conduct a systematic review and quantitatively estimate mortality caused by cats in the United States. We estimate that free-ranging domestic cats kill 1.4–3.7 billion birds and 6.9–20.7 billion mammals annually. Un-owned cats, as opposed to owned pets, cause the majority of this mortality. Our findings suggest that free-ranging cats cause substantially greater wildlife mortality than previously thought and are likely the single greatest source of anthropogenic mortality for US birds and mammals. Scientifically sound conservation and policy intervention is needed to reduce this impact.
To some extent, the Cat problem will take care of itself, in some places. It is probably true that there is a near 100% overlap in the rodents and other small terrestrial animals, as well as ground bird eggs, eaten by Coyotes and feral Cats. Plus, Coyotes eat Cats. So, in areas where Coyotes are becoming re-established, the Cat problem kinda goes away by itself.
Coyotes may affect cats in another way too, forcing exclusion zones.
a study at Ohio State University shows that coyotes keep down the cat population in the more natural urban/suburban areas in two ways — meals of cat and cat education. The latter is the most significant. The cats learn that life closer to houses is safer. Cats migrate out of the parks and live in areas where the researchers found the cats to be both fatter and less diseased. In effect, the urban area becomes divided into coyote zones and cat zones.
If you want to argue that the feral cats should not be killed, fine. Be prepared to take one (or several) in and work towards removal and adoption. But unless there are enough people to do that, the remaining cats simply have to be killed. It isn’t like not killing the cat is in any way humane, considering the number of animals it will kill over time. And no, they are not part of the natural environment. They are invasive species. The birds, reptiles, and rodents they would kill would have been killed, in some cases, by something else, but by something that is supposed to be there. Just as importantly, or more importantly, feral Cats have the invasive species advantage. For the same reason that other invasive do better than the natives, feral Cats outhunt native predators, and native prey are not as protected against them. Native carnivores are unlikely to cause local (or widespread) extinction of native forms, but feral Cats are.
Photo Credit: Martin_Heigan via Compfight cc
Here at 10,000 Birds 20 July – 26 July is Invasive Species Week. We use the term “Invasive Species” in the broadest sense, to encompass those invasive species that have expanded beyond their historical ranges under their own power, by deliberate introduction, or by unintentional introduction. The sheer number of species that have been shuffled around on our big earth is impressive, though we will be dealing with the smaller sample size of invasive avians and other invasives that effect avians. Nonetheless, this week will be chock full of invasive species. So batten down the hatches, strap on your helmet, and prepare to be invaded! To access the entire week’s worth of content just click here.