That all said, most people are not in the business of studying ecology. When people hear me or other birders listing a litany of reasons why outdoor cats are basically pests, they can become confused. Whats the problem? Haven't cats always eaten birds? How the fuck can you not like cats? Today, we will clear this all up.
The first thing that sets apart domestic cats from most predators here in the U.S. is that they are considered an invasive species. In simple terms, an invasive species is a non-native (aka alien or exotic) species that, when introduced to an ecosystem, may cause environmental (and frequently economic) harm. Invasive species are most often introduced to new areas by human activity...sometimes intentional, sometimes not. Invasive species do especially well (i.e. their numbers explode) when they lack predators, as cats essentially do. Many successful invasive species do best in areas disturbed by human activity, although many do just as well out in what is left of "the wild".
What are some invasive species in California? Rock Pigeons. Feral pigs. Eucalyptus trees. Mediterranean Fruit-Fly. African Clawed-frogs. Norway Rats. Cats.
Secondly, your cat is a domestic cat. Domestication is the process whereby a population of animals or plants is changed at the genetic level of selection in order accentuate traits that benefit humans...in other words, through breeding, people have made cats into what we want them to be. That means cats are comparable to, in terms of evolution, as a toy poodle, a weiner dog, a pot-bellied pig, a miniature horse or your typical dairy cow. Although they certainly retain some of the instincts of their ancestors, there is little more about domestic cats that can be called "natural".
So, as you can see, the modern cat is both domesticated and an invasive species; bred to suit the needs of humans, but sometimes capable of living in the wild...often they live in human homes, and take short forays into the outdoors at their leisure. In short...they do not fit well into any existing ecosystem, since they are a strictly human product.
Here are some things I've heard from cat-lovers over the years, and what you too can now respond to these statements with.
"Lions, jaguars and cheetahs are cats. Shouldn't biologists be worried about them killing birds too?"
Its true, those are all related to domestic cats to a degree, but saying a lion and Garfield are the same thing is like saying a human and an orangutan are the same things. Although there are some similarities, think about what your'e saying...would your cat Boots survive a night on the Serengeti Plain? Would you be ok with your 3 year old niece petting a lion? Do the lives of these animals really have much in common?
Besides the simple fact that these big cats primarily eat mammals (most birds are too small and agile for these huge predators), there are a slough of differences. The modern cat has been domesticated, the other wild cats have evolved free of intentional human influence. As top predators they have played an important part of their ecosystems for thousands of years, affecting not only populations of other animals but, as a result, the very landscapes they live in. Current populations of native animals are not at risk of becoming completely extinct due to predation by the big cats, because the native animals have evolved with these predators and have learned to be wary of them.
So, in the big picture, how is Boots The Cat different from a lion? Domesticated cats are relatively new to the scene, and have not arisen out of anything that can construed as "the natural order". Wildlife has not had time to adjust to this new predator, and therefore are at considerable risk in areas they are forced to share with domestic cats.
"My cat has a bell. It won't be able to catch birds"
Why would a bird think that hearing a small bell equals imminent death? Have you sent out a memo to all birds regarding the exact meaning of the sound of a bell? That makes no sense. Besides, a smart cat knows how to stalk prey quietly.
Unless your cat doesnt go outside, is missing a leg, or is extremely obese, you have no way to prove that. Even declawed cats (something fucked up in its own right) take birds. Cats frequently do not bring their kills home, so the owner would have no way of knowing.
I am looking at Prudence The Cat (left) as I type this. She is sitting on a pile of laundry and licking herself relentlessly. The fruits of her infrequent trips outdoors have only lead to bad flea outbreaks, getting wounded by another cat, and generally getting scared a lot. Being ill-equipped for the outdoors, I doubt she has had the opportunity for bird destruction...she is A Model Cat.
"My cat eats a lot. It doesnt need to kill birds."
Do you not know what a cat is? Most of what cats do make no sense. Cats kill things for fun probably just as often as killing things to actually eat. They are evil bastards...don't let their cuteness fool you.
"So what if cats kill birds? Its just nature"
Hopefully you all understand by now that your cat Shadow killing a phoebe in your backyard is not an act of nature, its pretty much an extension of the carelessness of people. You might as well be out there yourself with a BB gun. Would you call a duckhunter with a shotgun a natural predator? Cats are no more natural, and they don't have bag limits, hunting seasons, or a preference in what they catch.
"My cat needs to be outside. It is so much happier".
Lets keep it real here. I have met a lot of cats in my day. So have you. I have not noticed that indoor cats are catatonically depressed (no pun intended), nor the outside cats acting any happier than indoor cats, and I will bet you haven't noticed any big difference either. If you really think your cat will benefit from unrestricted access to the outdoors, consider this from the American Bird Conservancy: "Life for outdoor cats is risky. They can get hit by cars; attacked by dogs, other cats, coyotes or wildlife; contract fatal diseases, such as rabies, feline distemper, or feline immunodeficiency virus; get lost, stolen, or poisoned; or suffer during severe weather conditions. Outdoor cats lead considerably shorter lives on average than cats kept exclusively indoors."
I hope ya'll now have a better understanding of not only the brutal impacts of domestic cats on birdlife, but how far removed they are from anything that can be called natural. My advice? Don't feed feral cats, or any outdoor cats for that matter. Keep your cats indoors, and spay and neuter them. If you don't...we will have no choice but to unleash the pelicans.
Thanks to The Internet and Brittany Lee for today's photos.