FOCUS ON BIRD CONTROL: Pigeon Management

For virtually all pest management professionals, the question of how to manage excessive pigeon populations is becoming an increasing priority. Although pigeons provide benefits to the environment as scavengers (as well as being a source of joy to many people), excessive populations can cause a number of problems in the following areas: damage and economic loss, public health and safety, aesthetics (visual and acoustic), inconvenience and creation of insect breeding sites and serving as hosts of various parasites.

Pigeons, and to a lesser extent, European starlings and English sparrows, cause the majority of local nuisance bird problems. Birds can and do cause aesthetic problems. However, more serious is the economic damage caused by their acidic excrement (see photo below). Bird excrement causes damage and decay to metal and concrete surfaces, paints and coatings, limestone, marble and electrical components. In addition, bird droppings may cause health hazards, especially when roosting in large numbers, resulting in a great accumulation of excrement. This accumulated excrement serves as a food source and breeding site for other insect pests.

HEALTH HAZARDS. Pigeons, sparrows and starlings are highly social and are associated with humans. Therefore, these three species provide the greatest opportunity for transmitting pathogens to humans. There are five major potential health hazards associated with pigeons: encephalitis, salmonellosis, chlamydiosis, histoplasmosis and cryptococcosis. The main mode of transmission for the latter four is via inhalation of infected material or dried bird excrement. Dried excrement on window ledges or roofs near air conditioning systems or air vents is a potential source of infection as is contaminated dry soil when it is disturbed. Encephalitis is transmitted from birds to humans via mosquitoes.

It is reasonable to believe that many cases of bird- or pigeon-related illnesses are not recognized as such due to the mild and common symptoms they may produce. Many related illnesses produce chills, headaches, diarrhea, vomiting and fever. These and other symptoms may be misdiagnosed by the affected individual as a cold, an allergy or the flu.

Reported cases involving these diseases are not abundant. However, as indicated previously, many cases may go unreported. In addition, risk minimization is an important factor. Although rare, death has been associated with all five of the previously listed diseases.

Human illness should be a major concern when considering bird management. However, other factors, such as structural damage, economic losses and associated costs for cleanup and repairs can provide a strong rationale for managing pigeon populations.

In order to maintain a positive working relationship with the community, it is recommended that the use of toxicants in managing bird populations be used only as a last resort if allowed by state, county and local ordinances. A more integrated, long-term program would be to use the combination of exclusion, mechanical repellents and trapping in gradually reducing the number of pigeons affecting the area you’re servicing. The above methods are generally looked upon favorably by city officials. Often, these methods are the only management strategies that are allowable by municipal governments. Following is a brief outline of each control method:

EXCLUSION. Netting installed where major problems occur prevents roosting. PCOs should be available to assist with site identification and evaluation. However, due to equipment and material constraints, installation should be performed by those trained in working on building exteriors at various heights. Fewer roosting sites will cause a population drop due to unsuitable habitat. Mechanical deterrents designed to prevent roosting also may be installed where feasible.

TRAPPING. An ongoing trapping program should be in place to keep pigeon populations at a manageable level. Although labor intensive, live trapping and humane euthanasia has the following advantages:
1. Less adverse public reaction.
2. Only target species will be euthanized.
3. No risk of secondary poisoning or other environmental contamination as associated with the use of toxicants.
Nest removal may be undertaken but is extremely labor intensive since breeding occurs year round with peak reproduction occurring during the spring and summer.

CHEMOSTERILANTS. Ornitrol was the only chemosterilant registered for use in a pigeon management program. The product worked by sterilizing female pigeons for six months and male pigeons for three months.

However, chemosterilants are no longer an option as they have been voluntarily removed from the United States market by the manufacturer in 1994. However, the product still retains registration in Canada. In addition, the cost of a sterilization program could be prohibitive, with results not manifesting themselves for a period of several years.
 
CONCLUSION. A rough population count of pigeons affecting the area should be taken before implementing any bird management program. Once the previous control measures have been implemented, an ongoing population count should be done in order to evaluate project progress and to make adjustments in the program as dictated. The ultimate goal of the project is not to eradicate the entire pigeon population, but to reduce the number of birds to a manageable level.

By using all of these management practices, an integrated long-term pigeon management program can be developed that will fulfill the needs of the affected area along with maintaining a harmonious relationship with the community.

The author is a board certified entomologist and pest management specialist at the University of Michigan, Ann Arbor, Mich. He can be reached at dhodgson@pctonline.com.