At Home with the House Sparrow
This month's true story was inspired by an article that ran in the December 2006/January 2007 edition of the Audubon Naturalist News entitled The House Sparrow: Scourge or Scapegoat, which includes accounts of capturing, gassing and decapitating sparrows.
The introduction of house sparrows into the United States from England went far beyond the first 8 pairs of birds that were release in 1850 in Brooklyn, New York. Between 1851 and 1876, house sparrows were released in nearly every major city including Philadelphia, Boston, San Francisco, Salt Lake City, Saint Paul, Cincinnati, Portland, Galveston, and throughout various parts of Iowa, Missouri, Georgia, Rhode Island, and even Hawaii. As the house sparrow gained in popularity, bird breeders, public officials, and private citizens released the non-native bird into areas that had been cleared of predators and supplied with nesting boxes. Initially, the house sparrow was imported in the hope that it would control insects, only to discover that it was not insectivorous. Primarily a granivorous bird, the house sparrow thrived on livestock and poultry feed, as well as undigested grain found in horse manure. By the 1880s, the tide of public opinion had begun to turn against the house sparrow, as illustrated by an 1883 publication that said "The little sparrow has been declared an outlaw by legislative enactment and they can be killed at any time... they drive away all our native song birds... Let them all be killed." By 1887, many states had begun efforts to eradicate the sparrows, as Illinois and Michigan established bounty programs that paid children for killing the birds; in time, children discovered that they could quadruple their bounty by allowing house sparrow eggs to hatch. A detailed account of the American importation of house sparrow during the nineteenth century is given by E.A. Zimmerman in House Sparrow History.
Social behavior and Interactions
The house sparrow is aptly named, for it is an urban dweller that likes to nest under eaves and in wall crevices of houses and other man-made structures. The male house sparrow has a black mask and bib, and several studies have shown that the social status of male house sparrows can be predicted by the size of the black bib. House sparrows nest within close proximity to one another and will band together to "mob" or drive away crows and other intruders. Both the female and the male sparrow take an active role in feeding and raising their young. In the fall and winter, house sparrows gather in large flocks twice a day -- once in the late morning and again in late afternoon -- to preen and sing; the exact purpose for these gatherings is unknown. Like most wildlife, house sparrows are naturally wary of humans, but they have been known to develop relationships with people who feed them, and it is not uncommon for house sparrows to buzz a provider from behind and to engage in other forms of play that demonstrate interest and curiosity in humans. Sparrows are also know for whistling and tapping at windows in order to get a provider's attention, a behavior that suggests intelligence, as described in A Complete Guide to Bird Feeding by John Dennis:
"Unlike the ability to recognize people, window tapping seems to require a fair amount of intelligence on the part of the bird that engages in it. First of all, the bird must know that its benefactor reside inside the house. Moreover, the bird is aware of the part of the house its friends happen to be in. No energy is expended tapping the window in a barn, garage, attic, or empty room; it is a room where the bird knows it will get our attention."
House sparrows are among a few species of birds that have learned to manipulate electronic door sensors to gain entrance into fastfood restaurants and into home improvement stores where they often find safe nesting areas and plentiful supplies of loose seed.
The Audubon article states that "once house sparrows find a feeder... they tend to dominate, scaring off most other species". But a careful observation of a typical feeding station will reveal that it is often the song sparrow that scares off the song sparrow, the junco that scares off the junco, the cardinal that scares off the cardinal, and so on -- regardless of the amount of available food. Many species of birds are known to be territorial around feeders; a reader's submission to the July 2007 edition of Birds & Bloom Extra describes a male ruby-throated hummingbird that guards 5 sugar-water feeders, allowing no bird other than his mate to feed. Interestingly, it is house sparrows that often draw more desirable birds to backyard feeders and offer a protected environment, as described in in this excerpt by John Dennis:
"Whenever dicksissels have been found at feeding stations in the East, they have almost always been with house sparrows. There is also an element of protection in having a flock of house sparrows at feeders. None of our guests is so jittery and given to flying off with such little provocation as is the house sparrow... the sparrow's nervousness is communicated to other birds, and... the overall effect seems to be to keep the entire feeding stations company a little more alerted to cats, bird-hawks, and other dangers."
As described in the Audubon article, house sparrows are generally characterized as invasive birds. But this view can be subjective, for the evening grosbeak was a little known bird of the northern wilderness until about 1850 when it underwent an enormous population increase and range expansion. By 1890, the evening grosbeak had expanded eastward to the Atlantic coast and as far south as the Carolinas and the Gulf of Mexico. Yet, few would describe the grosbeak with its striking black and yellow markings as invasive. Similarly, the house finch, which is a native of western states but is now common throughout the East due to illegal trafficking in the 1940s, is a welcomed backyard guest and easily recognized by its attractive red markings and streaked breast.
As described in the Audubon article, house sparrows are often regarded as aggressive birds that crowd out more desirable species such as bluebirds and purple martins. This is a fundamental law of nature in action, for as Charles Darwin stated, "the species that will survive are not the strongest ones nor the smartest ones, but the ones that will adapt best to change." And it is here where the house sparrow has excelled, for as the Audubon article points out, the house sparrow has mastered the ability to adapt and survive in virtually every environment. Bluebirds and purple martins make attractive and desirable neighbors, but the onus is now on such birds -- from a scientific and objective perspective -- to also adapt, or disappear. Not exempt from the laws of nature, the house sparrow itself is also the target of aggressive birds such as blue jays, which prey on house sparrow fledglings, and grackles, which for reasons unknown tend to single out house sparrows over other species.
Dealing with House Sparrows>
By 1900, house sparrows were the most common bird in North America, but from 1915 to 1920, their numbers declined as automobiles and farm machinery replaced horses. Today, human activity that impacts the environment, such urban development and refuse management, is still the primary driver behind the rise and fall of sparrows.
According to a March 1892 article in an Indiana, PA paper, about 450,000 sparrows were killed during a 3 month long bounty program " ...but the frisky bird seems more numerous than ever." This is not surprising since studies have shown that there is a natural floor and ceiling with respect to the number of rats that a garbage dump will sustain, a number that is determined by the amount of available food. Killing a batch of rats has no long-term effect in controlling their number since nature simply fills the void with another generation until the floor is once again met. Only by properly managing the underlying environment can the rat population be controlled. Likewise, the killing of one batch of sparrows only leads to the killing of a second batch (which is precipitated by the first killing), which in turn leads to the killing of a third batch, and so on. Because of this ineffective cycle, the wholesale capturing and killing of sparrows is not advocated.
When they become too numerous, house sparrows often attract a variety of hawks and other spectacular birds of prey to backyards where such birds would not otherwise appear. This is one way to control the number of sparrows, as is the use of anti-sparrow birdhouses and feeders and the proper storage of household garbage and refuse from fast-food restaurants. Exclusion methods are very effective in controlling the population of unwanted sparrows, and homes and other structures should be examined in the fall to eliminate roosting and nesting places. Some states govern the use of traps and toxicants, which should be generally avoided since they can be nondiscriminatory.