To Have Borne Witness

Free Preview The threats to birds come from many unexpected places. I bet few people think of their pet cat as a bird menace of the first degree. After all, the occasional bird that our pets catch can’t possibly hurt bird numbers. Certainly one cat isn’t a serious threat, but a huge group of cats most definitely is. According to MapsoftheWorld.com, the US has 76 million pet cats; China has 53 million and the UK 7.7 million. The top ten cat countries have 204 million pet cats among them. The trouble is, not all cat owners are responsible with their little dears. Some even let them outside, and others even set them free when the people have to move, or otherwise can no longer look after them. There are now believed to be 60 million feral cats in the US, which is a little less than the number of pet cats. So if that relationship of pet to feral cats is similar in other countries it suggests that those top ten countries have a total of about 350 million cats. The 200 million pet cats are presumably well fed but what about the feral cats? What do all those cats eat? Most survive on wildlife. A 2010 report entitled Feral Cats and their Management from the University of Nebraska School of Natural Resources estimates that the US feral cats don’t just eat mice and rats, they also eat 480 million birds each year. This is a death toll that costs the US $17 billion if we are to believe the figures worked out by the good folk at the U of N. This sounds like a lot of cat-killed birds, but I can believe it. I had cats once many years ago. One was a ginger neutered tom who was affectionate, liked cantaloupe melon, and was too soft to catch anything. But his sister was a little black and white holy terror. I was walking one evening along a wooded lane and she had decided to follow me along the margin. Of a sudden, a man walking his dog came round a corner and that little cat, with a howl of anger, leapt from the bushes and fastened herself onto the poor dog’s head. I finally got her off and naturally apologized to the man, and to his quaking dog. I must say, she was the only patrolling-guard cat I have ever known, and before that evening I had no idea such an animal existed. I mention this anecdote as an indication of just how fierce that otherwise gentle little cat could be. While she lived with me I would often go downstairs in the morning to find animal parts strewn up and down the stairs. I was on the phone once when she strolled by with a snake writhing from each side of her mouth and I would guess she probably killed something most days of her life. The point to all this is that, though she was a very well fed cat, the killer instinct hadn’t left her. She lived to hunt. Her brother, the ginger tom, also enjoyed a hunt, but he was unwise in the ways of stealth, and invariably gave himself away before he got within a couple of yards of his target. Most of the cats I have known, whether at the farm in Somerset, at my parent’s home, or in my own home, have been killers. One barn-cat on the farm used to kill full-grown rabbits to feed her litter of kittens. That is one reason I haven’t had one for thirty years. I think we can assume that most of the other cats are also hunters. Let’s assume that each cat kills only one bird a week, but only during twenty warm weeks of the year. With those numbers, we finish up with 20 killings times 350 million cats which is 7 billion birds a year. If the cats kill only one bird a month for six months of the year, it is still 2.1 billion birds per year. Or at two birds a week for forty weeks a year we arrive at 28 billion killed birds. However, I fear that my high number may be the most accurate. A New Zealand study of 37 cats, found that they each killed 82 birds and 296 other animals per year.3 That number works out at 28.7 billion, so my lower figures could be serious underestimations. What is even more scary is that we are only counting the cats in the top ten countries. There must be at least double the number scattered all over the world, so the total number of killings for all the cats worldwide could potentially be double the 28.7 billion. Such numbers appear outrageous, and I sincerely hope they are wildly inflated. We can only hope that many cats have few chances to hunt. Pet cats are in actual fact an invasive species in the majority of countries where they live. Worldwide they are known to have been responsible for the extinction of at least 33 species of birds. In 2010 and 2011, Karl Evans of the UK’s University of Sheffield led a study of the effects that the mere presence of cats has on nesting birds. His research found that when cats appear, the nesting birds respond with alarm calls and nest-defense activities that alert third party predators. The predators, be they squirrels or corvine birds, then know where to look for eggs or young chicks. Not only do the cats assist others in finding the young birds, but also the very disturbance caused by the cats reduces future nesting successes of the parent birds.4 The American Humane Society estimates that a pair of cats can produce up to five litters a year ranging in size from two to ten kittens. If all survive and go on to breed that adds up to a total of 400,000 offspring over a period of seven years.5 The way things are going, the feral cats could soon wipe out a whole lot more wildlife than they have done already.