The house sparrow, Passer domesticus, is one of the most familiar, widespread birds in the world. The problem is, house sparrows are also invasive birds that disrupt other bird species. Many birders prefer to discourage house sparrows in order to attract a more diverse range of bird species in their backyard and to protect other species threatened by house sparrows’ aggression. Because these birds are not native in North America, it is permissible to use different methods to control house sparrow populations.
House Sparrow History
House sparrows are believed to be one of the oldest known birds. The house sparrow originated in the Mediterranean region and spread naturally throughout Europe and into eastern Asia. The birds were imported to North America in the 1850s for nostalgic reasons and to help control insect populations. By the time it was realized that house sparrows do not regularly eat insects outside the nesting season, the birds’ range had spread tremendously, despite belated eradication attempts. Today, there are an estimated 150 million house sparrows in North America alone, and the species is the one of the most abundant songbirds in the world.
In addition to being invasive in North America, house sparrows are also unwelcome and considered a problem in Australia, New Zealand, South America and sub-Saharan Africa.
Problems With House Sparrows
House sparrows can cause many problems for native birds, including:
- Competing for nesting sites, even killing adult birds, hatchlings and eggs
- Usurping food sources and reducing diversity at backyard feeders
- Crowding out less aggressive birds from traditional ranges and habitats
While all bird species may suffer somewhat from the invasion of house sparrows, species that are particularly vulnerable include:
These types of birds are often in direct competition with house sparrows for food sources and nesting sites, and house sparrows’ more aggressive behavior is often successful in displacing them.
Discouraging House Sparrows
Birders can take different actions to discourage house sparrows and make life easier for native birds. Just as it is necessary to pay attention to birds’ basic needs when attracting them, successfully discouraging house sparrows will take a concentrated effort to eliminate what attracts these invasive birds.
Eliminating favored food sources is one of the easiest ways to stop house sparrows from visiting. Birders who do not want to see house sparrows at their feeders should remove cracked corn, wheat, oats, millet and bread scraps from their backyard buffet. Sunflower seed should also be either limited or restricted to small feeders that sway in the wind, which can spook house sparrows but will not always be effective. To continue feeding backyard birds without attracting house sparrows, birders should fill their feeders with Nyjer, safflower seeds, suet, nectar, fruit and nuts, none of which are preferred by these aggressive birds.
It must be noted, however, that house sparrows are flexible and may still sample these foods, but they aren't as likely to overcrowd feeders without their favorite foods.
The types of feeders used can also make a difference. House sparrows prefer to feed on the ground or on large hopper or platform feeders; remove these feeder styles to discourage house sparrows from visiting. Instead, use clinging mesh feeders, socks or tube feeders with perches shorter than 5/8 of an inch to prevent house sparrows from perching easily. Clean up all spilled seed quickly to discourage ground feeding sparrows.
House sparrows easily visit bird baths for drinking and bathing. To discourage these birds, remove bird baths or add uneven rocks to the basin to break up bathing spots. Use misters, drippers or small hanging bird drink stations with exterior perches instead of full bird baths to provide water to other birds without attracting house sparrows.
Furthermore, investigate gravel areas and open soil to eliminate the dry, dusty patches that house sparrows use for dust baths.
House sparrows are highly adaptable birds that can shelter in a wide range of locations. While it would not be prudent for backyard birders to remove all shelter – native birds would have no shelter then – it is possible to minimize shelter for house sparrows. Keep garage doors and sheds closed to prevent birds from entering, and avoid putting out bird roost boxes that will encourage house sparrows to claim territories. Try to scare house sparrows away from sheltered spots in the evening so they will be forced to find less protected spots and may be more susceptible to nighttime predation. Installing mesh beneath a home’s eaves may also be effective in keeping house sparrows from roosting in those protected locations.
House sparrows aggressively compete with native birds for nesting sites, often injuring or killing other birds in the process. To prevent this behavior, avoid putting up bird houses or nest boxes until April 1. House sparrows typically begin choosing nesting sites as early as late February or early March, when other birds have not yet arrived in their breeding ranges. If a house sparrow has claimed a bird house, plug the entrance hole with crumpled paper or a rubber cork for several days until the bird moves on. Relocating boxes may also be effective, though it is just as likely that the house sparrows will discover the new locations. Bird houses made from PVC pipe can be effective deterrents, since house sparrows prefer wooden nest boxes. Bird house entrance holes should be smaller than 1.25 inches, though this may also exclude smaller native birds from using the house.
Once other birds have laid their first egg in a house, adding a “sparrow spooker” can be effective to protect the nesting birds and scare house sparrows away. A sparrow spooker is an arrangement of hanging Mylar strips that dangle above the roof of the birdhouse and discourage house sparrows from approaching.
Other birds are not as easily deterred and will continue to use the house.
Aggressive Control Techniques
In extreme cases of house sparrow aggression or entrenched populations, it may be necessary to resort to stronger control techniques that actively reduce the house sparrow population. Options include shooting house sparrows, trapping birds to kill them (relocation is not desirable because that simply moves the problem to another region) and destroying eggs or nests to prevent population growth. Before attempting these types of aggressive control techniques, however, it is wise to consult a wildlife management office – not not all tactics may be legal or suitable in certain areas. Any aggressive control techniques should also be carefully monitored so they do not impact other bird species that are protected under the Migratory Bird Treaty Act.
House sparrows are highly adaptable, aggressive birds that can cause problems for a number of native bird species. Actively controlling house sparrow populations can help manage these problems and increase bird diversity in your backyard.