Bird Exclusion and Dispersal
More than 400 species of birds can be found in Illinois. Most are welcome visitors because of their beauty, song and entertaining behavior, if not for the valuable role each plays in the environment. Yet, like plants, insects and other wildlife, birds can become pests when they find their way into places where people don’t want them and when their behavior becomes a nuisance or poses a health risk.
Although a bird’s song can be pleasurable, bird calls, chirping and chattering can, at times, create an annoying racket. Similarly, people that invite showy woodpeckers to bird feeders, want them gone when the males stake out their territories by hammering on structures. Other birds disturb garden plants and consume fruits and berries intended for the table. Herons and kingfishers will pluck fish out of garden fishponds. Birds nesting in attics, eaves, vents and porches are not welcome guests. And when birds consistently pepper parked cars with their corrosive droppings, when geese foul a golf course or when accumulations of bird droppings pose a threat to human health, bird management may be called for.
Proceed carefully, however. The Migratory Bird Treaty and Endangered Species acts prohibit the trapping, possession, or killing of most birds, their eggs and nests, without a permit. If you cannot positively identify the birds, consult bird authorities before you attempt to control them. Only house sparrows (Passer domesticus), starlings (Sternus vulgaris) and pigeons (Columba livia) are not protected by state or federal law. However, local ordinances may protect these birds. Be sure to check with local authorities before attempting control.
Both protected and unprotected species can be annoying and endanger humans. Nests in structures can be a fire hazard and a source of mite and insect parasites that can affect people. And, while the direct transmission of disease from birds to humans is uncommon, life-threatening diseases can be contracted from their droppings.
Histoplasmosis is perhaps the most important disease acquired from bird droppings. It is caused by inhalation of spores of a soil-inhabiting fungus (Histoplasma capsulatum) that grows where bird droppings accumulate. The greatest risk occurs when droppings accumulate on shaded soil where large numbers of birds (or bats) have established roosts. Disturbing the droppings, e.g., during clean-up attempts, causes the spores to become airborne. Most people who inhale the spores experience mild flu-like symptoms or no symptoms at all. But others, such as those with compromised immune systems and those who inhale large quantities of spores, can develop complications including respiratory problems resembling tuberculosis that can lead to death.
Persons attempting to clean up droppings that have accumulated over two or more years (fresh bird droppings do not support the fungus) should wear personal protection equipment, including respirators with high-efficiency particulate air (HEPA) filters, and wet the droppings during removal. Additional guidelines can be found under PUBLICATIONS in the right-hand column.
Unprotected Pest Birds
The house or English sparrow is the most common bird in cities. They are the all too familiar 6-inch long, brown and buff colored birds. Nests are a bulky arrangement of twigs on any available horizontal surface. Sparrows feed on grain, seeds, buds, fruit, insects and trash. The male is easily identified by its black “bib” and white cheeks.
The starling’s aggressive nature and nesting habits have probably displaced more native songbirds than either the house sparrow or pigeon have (all are species introduced from Europe). The birds are so aggressive that up to 10 percent of starling deaths are caused by fighting each other for nest sites. The birds will lock legs and peck each other in the face until one dies. Preferred nesting sites include holes or cavities in trees and structures. One in every three starling nests is “parasitized” by females that lay eggs in other females’ nests. Starlings measure 8-9 inches from tip of beak to tip of tail. Their plumage is black with some iridescence, but can also be brownish or spotted. Males have yellow bills, females black bills. They feed on seeds and fruits, but are especially fond of insects and trash. In large numbers, they can consume and contaminate feed and food at livestock feedlots and food-processing facilities.
Pigeons feed on garbage, insects, seeds and grain. While referred to by some as “rats with wings,” others have a different opinion and feed pigeons as they would pets. Feeding can increase the number of pigeons, and pigeon problems, in an area. Pigeons are fond of nesting on ledges and rooftops of multi-story buildings. They construct crude nests -- a simple pile of sticks, often cluttered with feathers, droppings and debris. The species was bred from the European rock dove and has been domesticated for hundreds of years. Hence pigeons are well adapted to urban life. As such, visual and auditory “scare tactics” are less likely to have an effect on pigeons than on other birds.
Protected Birds That Occasionally Become Nuisance Birds
Robins, Cardinals, Finches, Doves, And Other Protected Nesting Birds
You must obtain a state (if the bird is an endangered species) or federal permit to disturb protected birds. Thus, that robin nest on the ledge over your front door becomes problematic. Once a protected bird builds its nest on your property, federal law prohibits anyone from disturbing the bird or its nest, eggs or young. The best way to rid structures of bird nests is to prevent birds from nesting there in the first place, by watching for and deterring birds that attempt to build nests in the spring, and also by sealing, screening or otherwise blocking likely nesting spots on the structure’s exterior.
In spring, male woodpeckers stake out territories by “drumming” -- loudly pounding on hollow trees with their beaks. When dead trees are not available, the woodpeckers may turn to drumming on metal gutters or siding. Usually the noise causes more irritation than damage, though considerable damage can be done when woodpeckers drum on wooden structures.
Grackles, Blackbirds And Crows
Grackles are 11-14 inches long, black with iridescent plumage and V-shaped tails. Most types of blackbirds are slightly smaller and black with less iridescence. Likewise, crows are black, but much larger (15-18 inches from tip of beak to tip of tail) and have bristle-like feathers around their bills. Grackles, blackbirds and crows congregate by the thousands at roosts, causing an irritating cacophony; their droppings have the potential to cause human disease.
Geese have adapted well to city life and are found nesting on many urban lakes and ponds. Their presence is enjoyed by many, though their droppings are not. Parks, golf courses and neighborhoods with ponds can be inundated with droppings when large numbers of geese are present. Once established, geese are often difficult to force away from an area.
The mechanical removal of birds and their nests is a good option only for control of house sparrows, starlings and pigeons. These three species also may be live-trapped; but the release of birds, such as pigeons, even miles from the capture site, is ineffective as the birds are likely to return. Shooting is another option for control of unprotected species, but can be time-consuming and impractical when large numbers of birds are involved. Additionally, local laws often prohibit the discharge of firearms within municipalities. The shooting, trapping and poisoning of protected species is legal only with a permit from the U.S. Fish and Wildlife Service; such permits usually are not granted unless the birds pose a significant threat to human health. For details, contact the USFWS office in your region (Illinois residents should call 612-713-5436 or E-mail permitsR3MB@fws.gov.
Chemical options for control of unprotected birds are also limited. Most poisons designed to kill birds have been phased out, and those that remain are restricted use pesticides (for use only by certified pest management operators). One avicide formulation containing 3-chloro-p-toluidine, can be used only by United States Department of Agriculture wildlife specialists performing contractual bird control services. Another restricted use product, a “psychotropic” pesticide (4-aminopyridine), induces respiratory distress in birds, causing them to leave the area. New flocks, however, may then move into the vacated area. Also, overdoses can kill birds, and use of the product is not permitted in some localities. As with all pesticides, make sure there are no local regulations prohibiting the product’s use in your locale.
Other chemical products include bird repellents. Several sticky, polybutene gel products are available. One or more zigzag lines of gel are applied like caulking to surfaces birds land on. The glue-like gels do not contain poison but birds find them sticky and are reluctant to land. They are most effective when only a few birds are present (too many birds attempting to land will eventually remove the gel). Gel products must be applied to clean, non-porous or sealed surfaces, and must be scraped off and reapplied every year or two to maintain their effectiveness.
Another bird repellent is an extract of grape flavoring (methyl anthranilate). Several brands are available that can be sprayed onto trees, grass and other surfaces. The material is labeled for use against geese and several other species.
Whatever methods are used, the first step is always to identify the birds causing the problem, and to discover what is attracting them. Once these are determined, there are usually two options: remove what is attracting the bird, or exclude the bird. Generally the most successful methods rely on exclusion and/or habitat modification.
One means of exclusion is to frighten birds away. Unfortunately most “scare tactics” repel birds for only a short time, if at all. Included here are noise generators such as fireworks, firearm explosives (shell crackers), propane cannons, units that broadcast bird distress calls, and even ultrasonic devices generating sounds that neither people nor birds can hear. Devices that can be heard, can be as irritating to people as they are to birds.
Other scare devices are visual. These include expensive laser light “hazing” systems that are useful for repelling birds such as geese, crows, and pigeons. But flashing lights, flags, balloons, scare eyes, hawk/owl/snake likenesses, aluminum pie pans, and yes – even the classic scarecrow – are generally ineffective. When they do work, the effect lasts only a short while – until the birds become used to the device, or move elsewhere for reasons not associated with the device. In most instances, the success of scare devices is highly variable and depends on the type and number of birds, attractiveness of the site and alternate sites, timing (once established at a site, birds become more difficult to scare away), the type of devices used (it is best to use two or more devices in combination), and the skill and persistence of persons using the devices. In most cases, if control is to be achieved, the scare tactics must be employed consistently for three or four days. If the desired result is not seen within seven days, try something else.
More effective means of exclusion exist. These methods use caulk, metal wool, screen wire or hardware cloth to seal nesting and roosting spots on building exteriors. Where birds are feeding on fruit trees or roosting in small trees, the trees can be wrapped with netting to exclude them. As a rule, the following screen/net mesh sizes are best: ¾-inch for sparrows, 1 1/8-inch for starlings and 2 ½-inch for pigeons. Similarly, parts of structures used by drumming woodpeckers can be screened, netted, or filled with caulk, foam or other material to reduce the resonance, making them less attractive drumming sites.
When birds get inside buildings, mist netting can be used – but again, only for unprotected bird species. A mist net consists of very fine mesh that birds don’t see until they fly into it and become entrapped. The net should be strung across the bird’s flyways within the structure. Other areas may need to be blocked off, e.g., with sheets of plastic or cloth, to encourage the birds to fly toward the mist net.
To deter birds from landing on structures, especially commercial buildings, bridges, statues, etc., the use of netting, monofilament line, and wire springs, coils and spikes – even electrified wire – is recommended. These methods can be labor intensive, expensive and often require the services of a bird management professional, but provide control that is effective and permanent.
In addition to exclusion, habitat modification can be employed. Where flocks are roosting in trees, the trees can be pruned or thinned, making them less accommodating. In some cases, removal of the bird’s food and water sources is a practical and effective means of control. Rock and dense vegetation “barriers” can be planted along the shoreline of lakes and ponds to hinder geese attempting to come ashore. Dogs also can be effective when trained to chase the birds.
Unfortunately, the solution to bird problems is often complicated. Some methods work some of the time. Others don’t work at all. Some are labor intensive and expensive. But with accurate identification of the bird and of what is attracting it to a particular site, the proper control methods can be selected, and the problem solved.
For more information, see the Internet Center for Wildlife Damage Management's Web site (see RESOURCES).
NOTE: When pesticides are used, it is the applicator’s legal responsibility to read and follow directions on the product label. Not following label directions, even if they conflict with information provided herein, is a violation of federal law.
For more information, contact the Illinois Department of Public Health, Division of Environmental Health, 525 W. Jefferson St., Springfield, IL 62761; or call 217-782-5830, TTY (hearing-impaired use only) 800-547-0466.