Scientific Name:  Passer domesticus

Classification:

Phylum or Division:  Chordata
Class:  Aves
Order:  Passeriformes
Family:  Passeridae

Identification:

Adult house sparrows are about 6.25 in long, weigh about 28 g and feature short wings, short tails and relatively large heads.  Adult males have a black throat, a black v-shaped patch on the breast (darkest during breeding season and faded at other times), a light gray flank and belly, darker gray tail and crown, a chestnut-colored nape, broad white tips on the median coverts (which dull considerably outside the breeding season), brown feathers elsewhere on the wing and back and a black bill during breeding season (which is yellowish at other times).  Adult females have duller colors throughout – a duller gray crown with a lighter streak at and behind the eye, a gray-brown throat, breast, flank and belly, a gray tail and dull brown feathers on the wings and back.  The song is a series of single-note chirps.

Original Distribution:

The house sparrow was recorded originally in Eurasia, North Africa and the Middle East.

Current Distribution:

Currently house sparrows are established throughout North America (except for the northernmost section of Canada and Alaska), the sub-tropical part of South America, southernmost and northernmost Africa, the Middle East, Europe, Eurasia, central China, much of India, the western part of southeast Asia and southeastern Australia.

Site and Date of Introduction:

With respect to North America, eight pairs were released in the spring of 1851 in Brooklyn, New York.  House sparrows were also introduced between 1872 and 1874 by the Cincinnati Acclimatization Society.   Numerous similar introductions occurred in the years following the first release in 1851, and small numbers were collected within this country and transported to other parts of the country, resulting in house sparrows being established throughout the lower 48 states.  House sparrows were established in California by 1910.

Mode(s) of Introduction:

House sparrows were one of a number of species that were deliberately imported from Europe and released in the United States, in part to establish wildlife that was familiar to European immigrants.

Reason(s) Why it has Become Established:

The house sparrow lacked a natural predator when it arrived in North America, and several characteristics contributed to its population explosion in this country.  House sparrows typically live in or near human communities or sites where humans cultivate, a pattern that benefits these birds enormously by providing additional sources of food and sites for nesting.  Generalists in terms of their diet, house sparrows are able to thrive on a range of foods, including grains, seeds (both wild and those provided at feeders), scraps from humans, insects and spiders (while rearing young) and, less frequently, fruit, berries and vegetables.  Human structures also provide cavities and niches that are preferred nesting sites for this species.  House sparrows are both hardy and aggressive.  They begin nesting in late winter or early spring, often before migrants have returned, which results in migrant birds having fewer choices for nesting sites.  House sparrows typically raise two clutches of three or more chicks (most often four to five) each breeding season.

Ecological Role:

The role described in the literature available is primarily a negative one, that of displacing native bird species.  They also may play some role during the breeding season by keeping insects and spiders in check, although significant documentation of this effect is lacking.  (See the two sections below.)

Benefit(s):

There are claims that, on rare occasion, the house sparrow is useful in eradicating insects.  For example, an investigation by the United States Biological Bureau reported that house sparrows feed their chicks the larvae of the alfalfa weevil and cut-worms, both of which harm alfalfa crops. However, given the fact that, outside the breeding season, house sparrows primarily eat seeds and grains, it seems likely that their presence throughout the year would result in agricultural losses of other kinds, even if they could be relied upon to reduce insect pests during part of the year.

Threat(s):

Two significant threats were indicated by the literature:  agricultural losses and the displacement of native species of birds, including robins, song sparrows, chickadees, flycatchers, thrushes, tanagers, bluebirds and martins.  With respect to cavity-dwelling birds, such as bluebirds, sparrows aggressively claim and defend prime nesting sites and often displace other species that have established a nest and are incubating a clutch.  Aggressive flocks of house sparrows also discourage other birds from foraging in the same area.

Control Level Diagnosis:

If house sparrows had just been introduced or their territory were limited to one portion of the United States, we might assign them the “Highest Priority” for control in order to prevent their establishment in other areas and thus protect native birds.  At this time, an effort to eradicate them totally would have to be so enormous and powerful that it is likely it would produce other serious, negative effects on other species.  Since they have already spread to most of the continent, and since their hardiness, adaptability and fecundity make them difficult to eradicate, assigning house sparrows a “Medium Priority” might be more appropriate.  With such a priority, efforts to reduce house sparrows would be focused in particular habitats where migrating native species are in direct competition for food and nesting sites or in agricultural settings where high losses are due to this species.  Regardless of the diagnosis, it should be noted that it seems unlikely that this species can be reduced or controlled on a large scale without using aggressive (and presumably risky) methods.  Modest, targeted efforts may have the benefit of helping other species to flourish while not necessarily reducing dramatically the number of house sparrows.

Control Method:

One resource indicated that the use of pesticides and switching to monoculture crops resulted in declining numbers of house sparrows.  However, it is not clear from this paper whether these particular practices are safe with respect to other species.  No particulars concerning these methods were described.

In connection with the re-establishment of bluebirds and other native species, the North American Bluebird Society and the Cornell Lab of Ornithology describe specific measures that may be taken to discourage house sparrows from displacing the native species from the nesting boxes that are set up specifically to help increase the population of the native birds:

(1) Establish the boxes in more remote areas, away from human communities and farm buildings where house sparrows tend to dwell.
(2)  For the smallest cavity dwellers (smaller even than the bluebird), use a smaller entry hole on the nesting box.
(3) Although not fool-proof, boxes made of PVC pipe are less preferable to house sparrows but highly effective for bluebirds.
(4) Wait to establish or open nesting boxes until the migrants have returned, since sparrows typically begin nesting earlier.  Do not leave the nest boxes open during the winter for the house sparrows to use throughout the year.
(5) Do not encourage house sparrows by providing bird seed, or at least limit food to niger and unshelled sunflower seeds that seem to be less preferable to house sparrows.
(6) One of the more aggressive steps is to set up two boxes near each other – one for use by the bluebird and one as a decoy box for use by the house sparrow.  This method involves removing from the sparrow eggs, one or two at a time, refrigerating the eggs overnight, marking them with a magic marker and replacing them in the decoy box.  (Other methods were also described for disrupting the development of the embryos.)  The sparrows will continue to incubate the eggs for some time and leave alone the bluebirds to fledge their young.  If one simply destroys a sparrow’s nest, the house sparrow will continually rebuild or, in frustration, destroy the nests, eggs and young of other birds nearby.
(7) Various trapping methods were also described.  However, the use of traps runs the risk of trapping migratory birds that are protected by law.

References:

Berger, C., Kridler, K., and Griggs, J.  2001.  The Bluebird Monitor’s Guide.  HarperCollins, New York.

Bryant, P.J.  2002.  Chapter 9, “Exotic Introductions,” in Biodiversity and Conservation:  A Hypertext Book.  http://darwin.bio.uci.edu/~sustain/bio65/lec09/b65lec09.htm

Groschupf, K.  2001.  “Old World Sparrows,” in Groschupf, C., Dunning, J.B., and Sibley, D., eds., The Sibley Guide to Bird Life & Behavior.  Alfred A. Knopf, New York.

Harrison, C., and Greensmith, A.  1993.  Birds of the World.  Dorling Kindersley, New York.

North American Bluebird Society.  1999-2000.  “Fact Sheet:  House Sparrow Control.”  The North American Bluebird Society Web.  http://www.nabluebirdsociety.org/sparrow.htm

Pearson, T.J., ed.  1936.  Birds of America.  Garden City Books, Garden City, New York.

Sibley, D.  2000.  The Sibley Guide to Birds.  Alfred A. Knopf, New York.