Saturday, October 1, 2011
Invasion of the House Sparrows
You know that old expression, Be careful what you wish for? Well, I wished for a yard that was a haven for birds, and in the past week or so, that is what I got. It seems like hundreds of birds gather in my backyard every evening, creating a cacophony of cheeps and chirrups so loud that I can hear it long before I pull up to my garage. They fly in to the bamboo forest from the four corners of the neighborhood and snuggle in for the night.
There's just one catch. Almost all of them are house sparrows. (I do have a nice cardinal family and, as I described in my last post, some injury-prone mourning doves as well. But mostly sparrows.)
I do enjoy watching them hop and fly around in the gloaming, and if I walk out towards the bamboo as they're all bunking down for the night, I can hear a wave of them taking off with a mass susurrus of wings. On the other hand, it has made me thing twice about setting up bird feeders for the winter. They'd eat me out of house and home. I haven't actually counted, but it wouldn't surprise me if there was at least a hundred of them. (Even as I write this, the sun is just starting to rise, waking up the flock into a cheerful, chirping chorus.)
But, is there actually anything wrong with having so many house sparrows around? A lot of bird-lovers can't stand them, since they are non-natives and will compete with native birds for nesting sites, especially bluebirds and, from what I've seen of house sparrow nests spilling out of marten houses, purple martens. A member of the weaver finch family rather than being a relation to our native sparrows, they were brought from England and managed to install themselves just about everywhere.
Despite their negative qualities, I find it hard to be a hater. They're still birds. It's still fun to watch them do birdy things like dust bathe, find food, and hover over their fledglings. This attitude seems to be shared by author Sally Roth, whose book Bird by Bird Gardening I discussed in a previous post. She states that "their only 'bad' behavior is being too common," and does not try to exclude them from her feeders, as that would also exclude other species she would like to attract.
As it turns out, it's more difficult to indict a species for being the direct cause of another's decline than one might think. This article by the Cornell Lab of Ornithology discusses the difficulties in pinpointing these things for certain, although it does look like house finches might be outcompeting house sparrows, for a change. In other words, a native species' decline might just as well be caused by habitat or other changes, and the huge flock of house sparrows in my backyard is the effect rather than the cause.
Intuitively, that makes sense to me. They seem to love the bamboo--another non-native species. The two invasives seem quite happy together. The native species I find in my yard seem to prefer perching in the actual trees. I'm almost certain that when I get rid of the bamboo, my yard will not seem as welcoming to the hoard.
Although I'm hoping that removing the bamboo will thin the numbers, I wouldn't want them all to go away. For one thing, even though they are so common as to be considered nuisances here in the United States, house sparrow populations have declined precipitously elsewhere. In England (which I always think of as the "home" of the house sparrow even though the Internet has informed me that they are originally from the Mediterranean), numbers have dropped around 68% percent since the 1970s, and up to 90% in London. In the Netherlands, populations have dropped so much that they are now considered an endangered species. I also found Internet sites devoted to the decline of the lowly house sparrow in India.
This is all a bit disturbing. How on earth does one kill off house sparrows, which have to be among the hardiest little creatures I can think of? Here in Illinois they are everywhere humans are--nesting in signage on big box stores and chain restaurants, hopping across the asphalt at gas stations, even landing right on my plate as I ate at an outdoor cafe. The only bird more ubiquitous that I can think of is another invader, the starling.
No one knows for certain what has caused the species' decline. Suggestions include lack of food for nestlings, lack of habitat (What? They'll live anywhere!) and nesting sites, pesticides, changes in agriculture, and electromagnetic radiation from cell phones. I just have one bone to pick with these theories: wouldn't that mean that the sparrows would be dying off here in Illinois as well? Here in the agricultural wasteland of central Illinois, we just about wrote the book on monoculture fields and pesticides -- ah, the joyous sight of crop dusters overhead! -- and the sparrows appear to be thriving.
But any decline in bird populations should be taken seriously. There's a reason for the expression "canary in a coal mine" -- birds make excellent early warning systems. And for those who shrug and say, "So what if the birds go?," well, as the miners know, as go the birds, so do we. (As a brief rant, that's one of the things that drives me crazy about people who take a "Who cares about the environment as long as we're all making money" stance--where do they think we live? "The environment" is our environment too! Excuse me. Rant over.)
As a brief example, we can look to Chairman Mao's "Four Pests Campaign" of the Great Leap Forward, from 1958-1962. Chinese citizens were exhorted to kill the four noxious pests, rats, flies, mosquitoes and sparrows--in this case, the Eurasian house sparrow, which was considered to steal the farmer's labor by eating the grain from the fields.
The people responded enthusiastically, shooting sparrows from the sky, destroying nests, eggs and nestlings, and chasing the birds around while banging pots and pans until they dropped from exhaustion. Someone might say, "Well, so what, it's justified if the birds were eating their food and the people were hungry?" But it turns out that the sparrows eat more than grain; they also love insects.
The "Kill a Sparrow Campaign" was so successful that they were almost extirpated from the country--and the result was a plague of locusts and other insects of such proportions that crops failed, and a famine in which 30 million people died of starvation.
So this is why I tolerate the invasion of house sparrows in my backyard. It could be worse. There could be none. However, since I have no desire to feed them, when I do get around to putting some feeders up for the winter, I will follow the advice in Anne Schmauss, Mary Schmauss and Geni Krolick's book, For the Birds, to discourage them from dining: using seed mixes with no millet or using safflower seeds only; using tube or sock feeders that they find hard to cling to; and putting up suet blocks with no grain in them. I don't want to be mean...but there's just too many to feed!