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The House Sparrow: Scourge or Scapegoat?
By Kathleen Franklin
Photos by Dirck Harris
They are the kudzu of the skies, aggressive, opportunistic bullies with voracious appetites. Their plumage and markings are unremarkable and their song is a cloying, repetitive chirp. They are house sparrows — Passer domesticus — and they have become the scourge of bird enthusiasts everywhere, particularly aficionados of the Eastern bluebird and purple martin.
Imported to the U.S. by homesick immigrants in the 1850s, the house sparrow (actually a member of the Weaver Finch Family) has become one of the most common birds in the world. The initial 50 birds, introduced in Brooklyn, were joined by more importations to other cities, such as Salt Lake City and San Francisco, in the 1870s. By the 1940s, there were an estimated 150 million house sparrows in North America.
There are myriad reasons for the phenomenal success of this unremarkable-looking little non-native, invasive bird. First, house sparrows are vigorous breeders, generating as many as four broods (each consisting of anywhere from three to seven eggs) per season, compared to only one brood per season for Eastern bluebirds. One pair of sparrows can produce 20 chicks per season; theoretically, this duo could multiply to more than 1,200 birds in just five years.
Second, while any good real estate agent knows the mantra, “Location, location, location,” house sparrows are remarkably easygoing and indiscriminate tenants; just about any “cavity” close to human activity will do, whether it’s your dryer vent, a dirty gutter, the tool shed, the barn, or the lower half of the “C” in the CVS sign.
Although house sparrows are not commonly found in woodlands, grasslands, or deserts, they’ve been spotted playing house in Death Valley (280 feet below sea level) and in the Colorado Rockies (10,000 feet above sea level); because they are not migratory, they don’t succumb to the normal travel hazards faced by migratory species.
Third, house sparrows aren’t fussy eaters. They’re as happy eating grain and seed intended for livestock in rural settings as they are munching on muffin crumbs outside Starbucks. And they’re resourceful; according to Sialis, an organization devoted to bluebird conservation, house sparrows in Australia figured out how to trip the electric “eye” that automatically opened a set of glass doors to get food.
Male sparrows are intensely territorial, sacrificing a mate before relinquishing a nesting site. When the real estate market is tight, they won’t hesitate to claim another bird’s nest; in fact, house sparrows are home-invasion specialists, happily evicting other cavity-nesting birds. Because they start nesting in late winter/early spring, they often snatch up the best nesting sites, shutting out migratory birds like bluebirds, purple martins, and swallows. Territorial and aggressive, house sparrows will destroy the eggs and nestlings and even adults of other bird species, and they can dominate feeders.
What's a Backyard Birder to Do?
When it comes to controlling sparrow populations, there are two schools of thought—passive control and active control.
Passive control includes the following measures:
— Avoid cheaper seed mixes, such as those with a high percentage of millet, wheat, and cracked corn, and don’t put out bread crumbs and other baked goods designed for humans, as these are surefire bait for house sparrows and starlings. Instead, try sunflower (hearts or seeds), nyjer, and safflower seeds, as they attract other songbirds and are somewhat (emphasis on somewhat) less favored by house sparrows.
— Use nest boxes with openings less than 1 1/8-inch in diameter. This permits entry by chickadees, swallows, etc., while preventing access by house sparrows.
— Trim feeder perches to no more than one-half inch long so house sparrows have difficulty holding on.
— Place bluebird boxes and martin houses in the proper location, away from food sources and shelter likely to attract house sparrows.
— Don’t neglect purple martin houses or bluebird boxes; chase sparrows out at every opportunity and plug entrance holes until spring when their intended occupants arrive.
— Eliminate sparrow nests wherever and whenever you find them, and thwart nesting by closing up small openings around your house; flush out gutters regularly and patch up cracks in walls and roofs.
Active control involves trapping and either relocating or killing house sparrows. Relocation is problematic, not only because it relocates the problem, but because it does nothing to decrease the population.
Avid house sparrow opponents render the eggs infertile by shaking them vigorously and then piercing the egg with a long needle. Other methods include oiling the eggs with corn oil to prevent air from passing through the shell, freezing the eggs, and even boiling them.
Killing house sparrows—whether adult or embryo — predictably generates an emotional debate among some bird enthusiasts, but it is a far more efficient way to tackle the problem. House sparrows (like European starlings) are not protected under law, so it is legal to kill them. (House wrens, on the other hand, are protected, as they are a native species.)
Lola Oberman, longtime naturalist and Bethesda resident, author (The Pleasures of Watching Birds, published by Walker & Co., among others), and former columnist for this publication, is not shy about discussing her methods for sparrow control. “They’re terrorists,” Oberman says flatly, adding that she has used a ground trap for many years “until someone stole it,” she notes with some disgust. She applies pressure to each captured sparrow’s neck “until I just put it to sleep.”
Her neighbor, retired NIH cell biologist Emma Shelton, is equally sanguine in her control methods, quickly snipping off the heads of each bird. “I used to bag the birds and wrap the bag’s opening around my car’s exhaust pipe,” the feisty octogenarian explains. But that method is ineffective in the wake of stricter emissions standards.
Regardless of whether one wishes to relocate or kill captured house sparrows, most trappers agree that fall and winter are the best seasons for trapping them, since they tend to flock more during those seasons.
There are also different types of traps. In the ground trap category, the most popular appears to be the Hav-A-Hart trap, which is a wire or plastic-mesh box baited with seed and equipped with a weight-sensitive trip-lever. These traps can hold as many as a dozen birds. Some fans of these traps place a small mirror in the box to lure the first sparrow in; others are more likely to venture inside once the first one is caught.
It is important to note that other birds may wander into ground traps; these should be released immediately. Therefore, it is important to check each trap several times a day, especially on very hot days. Be careful in identifying house sparrows, particularly the females, as they often resemble our native sparrows.
Nest traps are also popular. This type of trap typically mounts inside the regular nesting box, operates via a spring-loaded mechanism, and is used during nesting season. Like ground traps, inbox traps should be monitored carefully.
Floyd VanErt, a longtime bluebird enthusiast who hails from Leon, Iowa, makes and markets several models of nest box traps. “I’ve trapped more than 4,000 in the last six years,” he says. “At one point, I was getting a couple of hundred a month.” He is reluctant to discuss his disposal of the sparrows he traps.
VanErt scoffs at relocation: “If you take ’em down the road, they’ll beat you home.” And, he says, he’s observed that the older males are the primary culprits in attacking bluebirds and their nests. As for feeder enthusiasts, VanErt recommends peanuts, nyjer, and black sunflower seed. “Stay away from millet and other grain-based seed," he said.
Are They Really Taking Over?
"Data show that the numbers are actually on the decline,” according to George Wallace, vice president and chief conservation officer for the American Bird Conservancy (ABC).
The available data back up Wallace’s assertion. According to the North American Breeding Bird Survey (BBS), compiled annually by the Patuxent Wildlife Research Center, the house sparrow population actually declined nationwide by 3.59 percent between 1980 and 2005. At the same time, the population of the Eastern bluebird increased during that same period by 2.94 percent.
In Maryland, the numbers are equally, if not more, encouraging. Since 1980, house sparrow populations have declined by 3.69 percent statewide, while Eastern bluebird populations have climbed by 3.01 percent.
Many observers suggest that the reason that house sparrows and European starlings are perceived as being more annoying and more plentiful is because there is less bird diversity.
As county governments, developers, and vigilant homeowners cut down sick, damaged, or just-plain-unwanted trees, natural cavities that would otherwise serve as bird dwellings have disappeared. Pollution, pesticides, and other human factors also have taken their toll. “Since we moved to this house in 1971, we’ve compiled a ‘yard list’ of 112 species either on or seen from the property,” says Oberman. “At least half of them haven’t been spotted in the past 10 years.”
“There’s no question that house sparrows pose a threat to bluebirds, particularly in areas where development is fast replacing open space with more favorable sparrow habitat,” says ANS Senior Naturalist Stephanie Mason. “Without this competition, Eastern bluebirds might be making an even stronger comeback. But thanks to greater awareness and the establishment of nesting-box trails, bluebirds can now be seen fairly commonly throughout the region.”
On the other hand, Wallace notes, the house sparrow has proved immensely useful in numerous areas of scientific study. Plentiful and easy to trap, the house sparrow is “the white rat of ornithology.” The house sparrow has been employed in more than 5,000 published studies of breeding, mating, disease resistance, and other aspects of avian biology.
George Jett, a retired EPA employee who lives near Waldorf, Maryland, suggests that backyard bird diversity can be encouraged simply by using different types of nest boxes with varying openings that do not all permit house sparrows to enter. “Place them in different areas of the property,” he advises, adding that overuse of feeders and poor feed choices have contributed to the perceived sparrow problem.
Jett also points out that house wrens and house finches also pose threats to the Eastern bluebird. “The house wren has practically exterminated Bewick’s wren,” says Jett, adding that relocation of house sparrows is “not a useful option” and that active control is the only reasonable method for keeping sparrow numbers manageable.
Shelton agrees as she recalls what many locals would find hard to fathom: “Decades ago, I could look out my office window at NIH and the rolling green hills below were practically blue with bluebirds.”
A fourth-generation native Washingtonian. Kathleen Franklin last wrote for the Audubon Naturalist News in the Aug/Sept 2006 issue, "Greenbelt: Smart Growth from the Get-Go.”