Damage Prevention and Control Methods

House sparrow, Passer domesticus. Male (left) and female (right).

Exclusion

Close all openings over 3/4 inch (2 cm) to exclude house sparrows from buildings. Replace the glass in broken windows or cover them with plywood or wire mesh. Block openings, like bell towers, with poultry mesh no larger than 3/4 inch (2 cm). Warehouse doorways that must accommodate human traffic can sometimes be effectively blocked by hanging a flexible wall of 4- to 6-inch (10-to 15-cm) plastic strips in front of the opening. These will not seriously impede human movements yet present an impassable barrier to sparrows. Poultry houses and feeders should be screened to exclude sparrows.

Attach signs flat against buildings to avoid providing roosting sites. Screen or block spaces between existing signs and buildings. Install slanted metal, plexiglass, or wooden boards (>45^o angle) over ledges, such as those under shopping mall overhangs or on old buildings, so sparrows cannot roost or nest on them. Eaves should be screened if the birds are able to squeeze into them. Block the spaces between window air conditioners and buildings to keep sparrows out. If possible, place fine mesh over architectural decorations on old buildings to prevent roosting. It is much more effective, however, to work with architects on building designs that eliminate ornamental patterns and holes that provide nest sites for sparrows.

Prevent house sparrows from roosting on ivy-covered walls by stringing plastic bird netting (green or black) over the vines. While not as satisfactory as removing the shrubbery, the mesh generally blends in with the plants and still prevents the birds from roosting and nesting in them. Place netting in front of ventilator openings to keep birds out of buildings. Examine ventilators, vents, air conditioners, building signs, ledges, eaves, overhangs, ornamental openings, and ornate designs for potential and existing bird usage and eliminate those sites where practical.

Sharp metal projections, such as Nixalite^® and Cat Claw^®, may prevent birds from roosting comfortably in an area. Sparrows can roost on ledges only 1 1/2 inches (3.8 cm) wide. Therefore, ledges and other niches must be completely covered. Placing monofilament lines at 1-to 2-foot (0.3- to 0.6-m) intervals may help to repel house sparrows from roosting sites. Electrified wires strung over roost sites have been effective, but it is an expensive alternative.

Protect small crop areas with plastic bird netting in situations involving high-value crops, such as grapes, berries, or experimental grains. This approach can be economical if netting is used for several years to protect the site. Leave no openings at the bottom of netted crop areas. Sparrows that get into fields through such openings and are unable to find their way out can cause considerable damage.

House sparrows can be discouraged at bird feeders by installing vertical monofilament lines at 2-foot (0.6-m) intervals around the feeders. Studies have shown that many other species of birds are not affected. Electric wires can be installed on perches of feeders to shock house sparrows when they land. This requires watching the feeder so the current can be activated only when house sparrows are attempting to feed.

House sparrows cannot use bird houses with openings 1 1/8 inches or less (2.8 cm); this size can be used only by wrens. Sparrows are attracted to and often colonize martin apartment houses if they are left unattended. Martin houses should be placed on tall poles in an unobstructed air space necessary for their aerial acrobatics. Block the entrances to martin houses until martin scouts appear in spring, back from their winter feeding grounds. Lower and clean the houses at the end of the breeding season. Bluebirds can be encouraged with nest boxes that have 1 1/2-inch (3.8-cm) entrance holes and a 3 1/2-inch (9-cm) hole bored in the roof, covered with 1/2-inch (1.3-cm) mesh. Bluebirds apparently can withstand wetting, but the sparrows like a tight roof overhead.

Cultural Methods

Destruction of roosting and nesting sites is one approach to solving a spar-row problem. Total removal of shrubs or even trees is an effective but extreme measure. In rural areas, removal of hedgerows adjacent to crop fields will limit the attractiveness of the area to house sparrows, but will also have a negative effect on other wildlife. Remove dead fronds from palm trees to eliminate roosting sites.

Several varieties of small grains are resistant to bird damage. Some sorghum varieties have a high tannin content in the early growth stages. Others have loose seed heads, on which sparrows are unable to perch and feed.

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Frightening

No truly successful alarm or distress calls have been found for house sparrows. Frightening devices designed for other species (fireworks, shell crackers, acetylene exploders, and cymbals) will move sparrows from an area for a short period. Sparrows, however, adapt quickly to frightening devices and will not be repelled by sounds for any great length of time unless the sounds are diversified and their locations shifted periodically.

Visual frightening devices can be helpful in some areas where crops are susceptible to damage for only a short period. Of the “scarecrow” devices, kites, balloons, and simulated bird of prey forms that circle above are the most useful. Sparrows can be frightened temporarily by mylar tape or shimmering foil strips. Alternate the use of several audio and visual frightening devices for best control.

4-Aminopyridine (Avitrol^®) is registered as a chemical frightening agent because the affected birds react so violently to it that the remainder of the flock is frightened out of the treated area. Usually large numbers of sparrows die before the repellent effect is achieved.

Repellents

Spread tactile repellents such as sticky bird glues on ledges to prevent roosting. These polybutenes are reasonably effective for periods of 1 year or more. They are messy and should be placed on tape or sealed masonry surfaces so they can be removed. They lose their tackiness after they become hardened by changing weather or covered by dust.

Methyl anthranilate (Fruit Shield^®) is currently registered for ornamentals, corn, sunflower, a variety of fruit crops, and structures.

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Toxicants

No toxicants or fumigants are registered for use against sparrows. State pesticide registrations vary. Check with your local extension or USDA-APHIS-Wildlife Services office for information on toxicant and repellent use in your area.

Trapping

Trapping is probably the most widely used method in attempting to reduce house sparrow populations in a small area. As most bird traps normally are live traps, nontarget species can be released unharmed. There are more types of traps available for sparrows than for any other bird. Sparrows that have been trapped once often become trap-shy. Therefore, traps alone are insufficient to remove an entire sparrow population.

Funnel Traps. These are the most commonly used traps available (Fig. 2). While funnel traps are probably the most easily entered of any trap, spar-rows can also escape from them with relative ease. Thus, they should be checked frequently and the birds removed. Where possible, decoy individuals should be penned in separate compartments inside these traps

Automatic Traps. These are counter-balanced multicatch traps (Fig. 3). House sparrows enter a compartment alone to feed on bait that is placed on a shelf in the trap. Their weight causes an “elevator” to drop to the lower level where the bird “escapes” into a closed cage. Without the bird’s weight, the counterbalanced “elevator” springs back into the original position ready for another passenger. It is more difficult to entice the birds into this type of trap than into the funnel traps, but the final catch is probably greater as it is almost impossible for the sparrows to escape.

Triggered Traps. These traps are limited by the number of house sparrows they can catch at one time (Fig. 4). In some cases the traps are not automatic and consequently require a watcher to tend them and spring them at the proper moment. The “clap trap” is one of the oldest bird traps, used first by ancient Egyptians.

Mist Nets. A final method of trapping is to entangle flying house sparrows in a fine net known as a mist net. Mist nets are placed across the flight paths of the birds in front of a dark back-ground. The nets cannot be seen until the birds blunder into them, become entangled, and are unable to extricate themselves. Mist nets also require considerable amount of time to set up and tend, and they are illegal in some states. Federal permits are required for trapping birds in mist nets. Nontarget species may be captured and must be removed and released immediately.

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Shooting

Shooting with air guns or low-powered firearms can be used with some success where local ordinances permit. Sparrows quickly become wary of a human holding anything resembling a firearm, so shooting from a blind is recommended whenever possible. An old method is to place grain in a windrow and shoot into a baited flock with an open-choke shotgun. Special ammunition known as “dust shot” (a .22 long rifle shell filled with No. 10 shot) or “BB caps” (a lead slug in a short .22 shell) are available. The effective range of these specialized tools, however, is extremely limited.

Other Methods

Nest Destruction. Discourage house sparrows from using an area by removing nests and destroying the eggs and/or young. House sparrows are very persistent, so this operation must be repeated at 2-week intervals throughout the breeding season. Use a long insulated pole with a hook attached to one end to remove nests that are located in high places. Nest destruction is also recommended in shopping malls and around building signs in urban areas. The nesting materials should be collected and removed to make it harder for the birds to find materials for new nests.

Predators. Cats and sparrows are both abundant in the same human-altered habitat. A study in one English village found house cats reduced a resident house sparrow population by 80% during a year. One farmer has devised a system using predation to control house sparrows by building catwalks around the inside of his barn at rafter level. Scrap lumber was used to provide his farm cats access to locations where sparrows usually roosted or nested. Once the cats were able to patrol the barn, the sparrows quickly vacated the building.