Integrated Pest Management

IPM Manual for Structural Pests in British Columbia

Chapter 11: Birds

Learning Objectives

When you have completed this lesson, you should be able to:

Describe the damage caused by starlings and pigeons.
Describe why monitoring activities of pest bird populations is important.
Describe the use of physical controls to deter birds from roosting and nesting.
Describe devices used to startle and repel birds.
Describe the precautions and methods of use for 4-aminopyridine (Avitrol®).

Identification

Drawing of starling Starlings and pigeons are common problem birds in British Columbia.

Starlings are robin-sized birds. The adults are dark with light speckles on their feathers in the winter and purplish-black and green in summer. The bill of both sexes is yellow from January to June, and dark at other times. Starlings roost in large, noisy flocks and defecate on buildings. They build their nests in inaccessible holes, crevices and confined spaces, making control of established nests difficult.

Drawing of pigeon Pigeons are the most serious pest birds associated with urban buildings. They are primarily seed and grain eaters,but will feed on garbage, insects, scraps and other foods offered by people. Pigeon droppings deface buildings and contribute to the deterioration of buildings, equipment and stored products. They are a serious and constant public health concern as they can transmit disease to both humans and animals.

Monitoring

To prevent or remedy nuisance bird problems most effectively, it is necessary to observe the activities of the bird populations, particularly with respect to finding their favourite perching sites.

It is important to observe pigeons, in particular, at several times of the day as their activity patterns differ throughout the day. Feeding, roosting and loafing sites are separate, thus the best control measures for each site will also differ.

Action Decisions

Birds are usually not considered a problem unless their numbers are quite high or they are roosting in a sensitive site, such as a food warehouse. The tolerance level for birds has generally been surpassed by the time the pest manager is called. It is important to assess the extent of the problem as the tolerance levels vary with the situation.

Prevention

Ideally, buildings should be constructed in ways that minimize roosting and nesting sites that attract birds. On existing buildings, access to ledges can be barred by installing permanent barriers (described below). Food sources should be eliminated where possible, especially grains and food scraps. This may involve coordinating the efforts of all businesses and residents in the area where birds are a problem.

Drawing of wire bird barrier Examples of bird barriers are:

galvanized wire mesh screen
bird netting
wire prongs or spikes
stainless steel wires, spaced along the entire length and width of landing surfaces

Although expensive, the installation of various patented spiked or pronged bird barriers provides a long-term protection from bird problems and can totally exclude birds such as seagulls and pigeons.

Caution should be taken when using bird netting as other species can become entangled in the nets. Also, netting can be objectionable from an aesthetic point of view. In wet and icy conditions netting creates a spider web effect.

Controls

Preferred Controls

It is possible to force problem birds to move to other, less problematical nesting or roosting sites by using devices that startle birds or drive them away from the area.

Startle Devices: The purpose of startle devices, such as audio tapes of alarm calls or shots from propane cannons, is to deceive birds into believing that there is danger. All startle devices are temporary, as birds soon learn that they are not punished by the sound.

Alarm Recordings: Starlings can be effectively repelled from over-night roosting sites by playing recordings of their alarm and distress calls as they try to enter the roost sites. The recordings must be played each night for at least three nights to obtain the desired effect of moving the population to a different roosting site.

Predator Mimics: Helium-filled balloons with huge eye spots on can be used to frighten birds away from some areas. Silhouettes of hawks mounted on windows and plastic statuettes of owls mounted on roof tops are also used to scare birds away.

Other Controls

Population Control: This involves killing the problem birds. Live trapping, using loft trap or funnel traps, can be effective for pigeons. Once the birds have been trapped, they must be destroyed. If released, they will return to the same sites. The most humane way to kill trapped birds is by breaking their necks.

Pesticides (repellents): Avitrol® (which contains 4-aminopyridine) is available for bird control in B.C., but only under a pesticide use permit. It is a restricted product because it is lethal to all birds and has high acute toxicity to mammals. Avitrol is considered a bird repellent, not an avicide, because the birds that consume it make distress cries, which frighten away the rest of the flock.

The Avitrol treated bait is mixed with untreated bait so that only a few birds of a flock are affected. Prebaiting trials must be conducted and if the mortality rate is excessive the bait must be removed or diluted. Dead birds must be removed daily. Use of Avitrol should be considered only in special situations, such as in a large institution where the birds are causing a serious nuisance or where they are a workplace hazard.

Evaluation

Post-treatment evaluations should include visual inspections to assess whether the bird populations have been satisfactorily reduced or sufficiently repelled from the problem sites.