Feral Pigeons

Feral pigeons, Columba livia, are descendants of the rock dove of Europe, Asia, and Africa and belong to the Columbidae family of birds. They have a long history of being raised and kept by humans. The pigeon was believed first brought to this country as a domestic bird in about 1606, and it is now found in a feral (wild) state in virtually every city. Many consider feral pigeons interesting and even attractive; however, when they become numerous, they invariably take on the status of a pest when they conflict with mankind's activities or present health problems.

Feral pigeons adapt well to human-made environments and are the most troublesome bird pest in urban areas, as well as in small rural communities. The abundance of shelter provided by the design of many buildings assures that pigeons will have ample places to roost, loaf, and nest. Food and water is often in adequate supply, but when it isn't, the birds seek these necessities from nearby rural or undeveloped areas which are generally within flight range.

Pigeon droppings deface and accelerate deterioration of statues, buildings, and equipment and foul areas where people may walk or work. Pigeon droppings and nests clog drain pipes and air intakes, mar window sills, and render fire escapes hazardous. Their droppings and feathers can contaminate large quantities of stock feed and food destined for human consumption.

The serious and constant public health problems they create are unmatched by any other bird species. They are known to carry or transmit pigeon ornithosis, encephalitis, Newcastle disease, histoplasmosis, crypto-coccosis, toxoplasmosis, pseudotuberculosis, pigeon coccidiosis, and salmonella food poisoning.

CONTROL. A number of control options are available for resolving pigeon problems including sanitation, bird-proofing buildings, trapping, repellents, toxicants, etc., yet often the problems are such that it taxes available control measures to the maximum. To solve many bird problems requires a substantial amount of ingenuity and imagination, simply because bird problems vary so greatly in their environmental and physical settings and in their biological complexity. Feral pigeons are not protected by federal laws, but state and local laws should be checked before reductional control through shooting, trapping or poisoning is attempted.

Good sanitation, in the way of removal of spilled food or refuse, can do much to reduce the attractiveness of an area to pigeons. This depends on the situation and whether or not the food source can be effectively and economically limited. The removal of nests and nest sites also may be included as part of a sanitation program.

The best permanent solution to pigeons and other birds that roost or nest in or on buildings is to "build them out" by making the site pigeon-proof. This is easily said but is often difficult and/or expensive to accomplish. Openings in buildings, exposed rafters on overhanging dock roofs, bridge bracings, etc., can be screened with rust-proof, 3/4-inch wire mesh, which will also keep out sparrows and starlings. One-half-inch mesh would be needed if rats are also to be excluded. In recent years, plastic and polyethylene bird netting has for the most part replaced the use of wire for pigeon-proofing (Figure 1). Bird netting, manufactured by several firms, is much less expensive, and because of its light weight can be installed over expansive areas at much less expense than wire mesh. It is also less visible than wire screening but generally deteriorates more rapidly and thus must be replaced more often. Netting is by far the most commonly used approach to pigeon and other bird problems associated with buildings.

Nest destruction can be helpful in preventing pigeon populations from increasing, but to be effective, the nest and eggs must be destroyed at two-week intervals. Nest removal is most effective when used in conjunction with other types of reductional control. By itself, unless carried out over a very long period, it has little effect on localized pigeon populations. To be efficacious, destruction of the nest must be continued until natural mortality accounts for the surviving adult birds.

Sharp pointed wires or anti-landing projections, such as wire prongs, sheet metal spikes, looped wire, etc. (Deter,^® Bird Barrier Coil^TM) can be highly effective as physical barriers in preventing pigeons and other birds from perching on ledges and beams of buildings. The temporary discomfort inflicted by the spikes or the inability of the birds to light causes the birds to avoid these surfaces. Several kinds of these devices (e.g. Nixalite,^® Cat Claw^®) are commercially available in strip form that can be installed with clip fasteners, wire ties or an appropriate adhesive. Wire or strips of sharp projections can be permanently installed on window sills, ledges, rafters, or other locations where birds might loaf, roost or nest. Wide surfaces may require two or more parallel rows of projections. The manufacturers provide instructions for effective installation. The expense of the devices and their installation can be substantial, but their permanent efficacy often justifies the cost. Pigeons can be kept from roosting on support cables, pipes, and narrow beams by stretching taut a piano-type wire about an inch or two above the item or surface. This wire is too small for them to light on and prevents them from perching on the surfaces beneath.

Pigeons and other birds also can be discouraged from landing on ledges by installing thin wires supported by short posts and pulled taut by small springs. Birdwire^TM by Bird Barrier and Springwire^TM by Hot Foot America are two examples of this device. The wires are installed at varying heights spaced 3 inches/7.5 cm apart across the width of the ledge (Figure 2). Another unique exclusion device is Bird Barrier's Daddi Long Legs^TM (Figure 3). This device can effectively exclude pigeons from landing on large surface areas, such as storage tanks, air conditioner units and wide ledges.

Installation of grounded electrical wires on roosting surfaces can be highly effective. Such an installation is expensive but offers a relatively permanent solution in keeping pigeons off building ledges. The wires carry a high voltage but low amperage current similar to cattle-type electric fences and intermittently shock the birds without killing them. Such installations are not without some problems, for they can be shorted out by an accumulation of dirt on insulators and by sticks and debris which may fall on the wires.

Chemical bird repellents that are sticky to the touch are available for application to ledges and beams where pigeons may roost or nest. These nontoxic tacky materials are designed to cause the birds to avoid the treated surfaces but not entrap them. Even though they effectively repel birds in many situations, their tackiness is lost with time, principally through an accumulation of dust.

Several sticky repellents are sold in a gel form in cartridges for application with caulking guns. The material is laid down in a wavy bead on the edges of roosting surfaces. While the gel form is the most popular, some tacky repellents are available in viscous liquid form to be sprayed or brushed onto surfaces. Small squeeze tubes and aerosol cans are also marketed for convenient application over relatively small areas.

Frightening devices in the way of auditory or visual repellents are, in general, ineffective for pigeons. Pigeons quickly become accustomed to plastic owls, rubber snakes, aluminum twirlers, flashing lights and the like. Auditory-type repellents, such as automatic exploders (gas cannons), electronically produced noises, bioacoustics (alarm calls), pyrotechnics and shell crackers, although effective for some other bird species, rarely give desired results with pigeons.

Live-trapping of pigeons can be a very effective method of control. A variety of traps have been used, including loft traps, funnel traps and bob-type traps; with few exceptions, the bob-type trap is the most effective. The sizes of these traps vary considerably, from being large enough for birds to walk into to only 10 inches/25 cm high and 18 to 24 inches/45 to 61 cm in width and length. Regardless of size, the bob-type traps all work on the same principle. The door or entrance through which the pigeons are lured is the key feature of the trap and consists of a row of evenly spaced individual, one-way, free-swinging bobs. These bobs permit the pigeons to push them upward and inward to enter the trap but prevent their exit. Grain (e.g. wheat, milo and cracked corn) is scattered at the door entrance to entice the birds into the trap. One to three live decoy pigeons in the trap greatly improve trapping efficiency. Water and food have to be provided for the decoys. Live catch traps should be serviced frequently to remove captured pigeons. Various methods are used for disposing of trapped pigeons, but in no case should they be taken away from the area and released, for the pigeon's homing ability can defeat any trapping and release program.

Shooting, where legal, is another option in pigeon control, but is very time consuming if more than just a few birds are involved. Where permissible, shooting with a .22 rifle with bird shot or short range "BB" can be effective. Shotguns and high-powered air rifles have also been effectively used. Careless shooting can be hazardous to people and can damage structures.

Toxic Rid-A-Bird perches can be highly effective for pigeon control but require considerable knowledge of bird behavior for proper and effective placement. The toxic perch is essentially a hollow metal tube 2 feet long with a lengthwise wick that contacts the perching birds' feet and permits transfer of the toxic solution from inside the tube to the surfaces of the feet. The avicide, fenthion, is absorbed through the skin or groomed from the skin in amounts that cause death. The perches are not placed in a casual way wherever the pigeons might happen to light, but only in select locations where pigeon roosting is highly predictable. In this way, well-placed perches are capable of controlling hundreds of birds. Perch installations must be serviced at regular intervals.

The chemical frightening agent Avitrol (amino-4-pyridine), sometimes referred to as a psychochemical, is available as a bait or concentrate and is quite effective for pigeon control. Avitrol is lethal to the birds that ingest sufficient quantities, but prior to death, the affected bird, depending on the species, may display erratic behavior and emit distressing cries which, in turn, frighten the other birds of the flock. The treated bait is diluted with clean bait to limit the number of birds which will actually consume a biologically active dose. In this way, by dosing a relatively small number of birds, the material is capable of producing flock-alarm reactions which repel the rest of the birds from the area. Prebaiting is absolutely essential prior to baiting. Repeated application of bait may be required until the population ceases to return to the area or until an acceptable population limit is attained. After an initial success, bait need only be applied periodically following prebaiting to keep pigeons from returning to the area.

Achieving control of feral pigeons may be challenging, but with the many techniques available to PCOs, success is attainable. The key is to study the specific environmental issues concerned, and then choose an appropriate strategy.