House Sparrow, Passer domesticus | Invasive Species

Invasive exotic species are those introduced species which benefit from their new environment such that they increase their population range significantly over time. Invasive species are currently recognized as one of the main threats to global biodiversity.

House Sparrows, also called English Sparrows, were introduced to North America in the 19th century. They are now permanent residents found across the United States and Canada, almost always near areas of human habitation and disturbance or areas with a reliable food source, such as barns or granaries. They nest in structures ranging from gutters and downspouts to thick shrubs and bushes, but readily use nest boxes when available. They outcompete native cavity-nesting birds, and are known to destroy nests and eggs, and kill nestlings and adults while taking over an occupied nest site.

House Sparrows, also called English Sparrows, outcompete native cavity-nesting birds, and are known to destroy nests and eggs, and kill nestlings and adults while taking over an occupied nest site — especially those of Bluebirds and Tree Swallows.

Background

Size and Shape

House Sparrows aren’t related to other North American sparrows, and they’re differently shaped. House Sparrows are chunkier, fuller in the chest, with a larger, rounded head, shorter tail, and stouter bill than most American sparrows.

Color Pattern

Male House Sparrows are brightly colored birds with gray heads, white cheeks, a black bib, and rufous neck — although in cities you may see some that are dull and grubby. Females are a plain buffy-brown overall with dingy gray-brown underparts. Their backs are noticeably striped with buff, black, and brown.

Behavior

House Sparrows are noisy sparrows that flutter down from eaves and fencerows to hop and peck at crumbs or birdseed. Look for them flying in and out of nest holes hidden behind shop signs or in traffic lights, or hanging around parking lots waiting for crumbs and picking insects off car grills.

Habitat

House Sparrows have lived around humans for centuries. Look for them on city streets, taking handouts in parks and zoos, or cheeping from a perch on your roof or trees in your yard. House Sparrows are absent from undisturbed forests and grasslands, but they’re common in countryside around farmsteads.

Diet

House Sparrows eat mostly grains and seeds, as well as livestock feed and, in cities, discarded food. Among the crops they eat are corn, oats, wheat, and sorghum. Wild foods include ragweed, crabgrass and other grasses, and buckwheat. House Sparrows readily eat birdseed including millet, milo, and sunflower seeds. Urban birds readily eat commercial bird seed. In summer, House Sparrows eat insects and feed them to their young. They catch insects in the air, by pouncing on them, or by following lawnmowers or visiting lights at dusk.

Nesting

House Sparrows nest in holes of buildings and other structures such as streetlights, gas-station roofs, signs, and the overhanging fixtures that hold traffic lights. They sometimes build nests in vines climbing the walls of buildings. House Sparrows are strong competitors for nest boxes, too, at times displacing the species the nest box was intended for, such as Bluebirds and Tree Swallows.

House Sparrow nests are made of coarse dried vegetation, often stuffed into the hole until it’s nearly filled. The birds then use finer material, including feathers, string, and paper, for the lining. House Sparrows sometimes build nests next to each other, and these neighboring nests can share walls. House Sparrows often reuse their nests.

Deterring House Sparrows

For the reasons outlined above, you should not allow House Sparrows to breed in your nest boxes. There are measures that you can take to prevent them from breeding in your boxes. Unfortunately, a completely sparrow-proof nest box does not exist. There are several styles that seem to deter the sparrows for a while, but ultimately if these birds are desperate, they will eventually use the box.

Placement

The most successful method for preventing exotic species from breeding in your nest boxes is simply to move your boxes. Only place your boxes in areas that do not have these birds. House Sparrows prefer to be near human habitations, and starlings also frequently inhabit agricultural areas with abundant grain. Therefore, placing your nest boxes in natural areas away from densely-populated locations will prevent many non-target birds from ever finding them.

Avoid Feeding

Another simple way to reduce the number of House Sparrows around your property is to avoid feeding them. House Sparrows prefer smaller seeds like millet, cracked corn, and milo, which are plentiful in inexpensive bird seed mixes. European Starlings, on the other hand, like premium black-oil sunflower seeds. Bird enthusiasts must accept that wherever there is abundant food, so too will there be House Sparrows. If you do feed wild birds, offer foods that these species do not appreciate, such as safflower for Northern Cardinals, nyjer or “thistle” seeds for finches, and nectar for hummingbirds. Avoid putting out mealworms and suet, and scattering seed on the ground. Feeders with short perches and small ports are also less attractive to these two species.

Exclusion

House Sparrows can fit through entrance holes as small as 1 1/4”, therefore most cavity-nesting songbirds using nest boxes are vulnerable to House Sparrow competition. There currently is no scientifically-documented way to exclude House Sparrows that works permanently, but some monitors have observed that Gilbertson PVC boxes are often avoided by House Sparrows. Your best bet may be to use a more active method of managing House Sparrows. If you prefer, you may alternatively choose to offer only boxes that are not as vulnerable to exotics (e.g., chickadee boxes, Chimney Swift Towers, or nesting platforms).

Another way to deter the aggressors from nesting is to put up nesting boxes they don’t like such as the Hughes Slot box. House Sparrows prefer a deep box because they build the dome. A shallow box prevents them from building the dome and the slot gives native birds an escape.

Timing

Because House Sparrows do not migrate, they have a competitive advantage when it comes to having first pick of suitable nest boxes. By waiting to open your nest boxes until migratory birds return, you can ensure that they have a better chance of finding an unoccupied site. Simply plug the entrance hole of your boxes until nesting season begins. Note that this means that your resident chickadees, titmice, and nuthatches may also have to wait for the migrants to return.

Escalation to More Active Control

Because House Sparrows are exotic species, they are not protected by the Migratory Bird Treaty Act. Therefore nest box monitors are legally allowed to remove or harass them. Below we list some humane, legal actions for controlling or deterring them.

Here are several strategies you may wish to consider:

  Nest Removal: When they begin nesting, remove nesting materials every few days.
  Incubation Fake-out: Trick the birds into incubating eggs that will never hatch by replacing their eggs with wooden eggs.
  Trapping: Where populations of exotic species are high, trapping may be the only effective means of managing invasive species. Here are reviews of House Sparrow Traps.

Further Reading:

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