DAIRY BARN BIRDS
by USDA/APHIS/ADC

In rural areas, pigeons, starlings, and house sparrows are attracted to dairy farms, where food and shelter are readily available. Populations of these three bird species usually increase around dairy barns during winter months, when snow cover limits access to food and water. Barns provide warm shelter on cold days, and feed troughs and bunkers provide an easy source of food. During winter, birds often consume and contaminate large quantities of feed intended for livestock. Starlings may consume up to 50% of their body weight in grain each day. Loss of feed may be quite significant. A flock of 200 starlings may consume 175 pounds of grain per week, and contaminate even more with their droppings. In addition, birds may create fire hazards by nesting on light fixtures and wiring in barns, and their droppings may contaminate bedding material and water intended for livestock.

Birds may also pose health hazards to both cattle and humans working in dairy barns. However, because birds have higher body temperatures than mammals, most of the bird pathogens do not flourish in healthy, non-stressed cows or humans. Some noteworthy exceptions occur in the salmonella and systemic (internal) fungal families.

Salmonella is a family of bacterial disease-causing organisms, of world wide distribution and major economic importance. Many of these pathogens arc capable of spreading disease to humans. Salmonella infections in birds, cattle, and humans tend to be intestinal, but generalized infections also occur. These infections may lead to death, but most are medically treatable. Young and old cattle tend to be more susceptible, with two to four week old calves most apt to contract severe infections. In mature cattle, salmonella may cause abortions, or a decrease in milk production. There are 81 different types of salmonella that cause infection in cattle. Salmonella may be transmitted by direct contact, consumption of fecally contaminated feed or water, or inhalation.

Systemic mycoses are fungal diseases that affect internal organs. Two notable diseases in this group that infect cattle are histoplasmosis and cryptococcosis. Both of these disease organisms are found in bird manure. Pigeons are more commonly associated with cryptococcosis, while starlings or pigeons may be associated with histoplasmosis. Histoplasmosis proliferates in less harsh climates, and is more commonly found in the central Midwest states. It is usually contracted through inhalation of spores, and causes a respiratory infection that healthy cattle recover from without medical treatment; however, it is potentially fatal in humans. Children are more susceptible to this mold than any other mycotic infection.

Cattle may become infected with cryptococcosis by breathing spores from an environment rich in dried bird manure, consumption of contaminated feed or water, contact with contaminated milking equipment, or through infusion medications contaminated with bird feces. In cattle, cryptococcosis appears as a primary infection of the mammary glands. The mastitis caused by cryptococcosis can be quite severe and non responsive to medications, as well as difficult to diagnose. Cryptococcosis may also cause a decrease in milk production, and loss of appetite. Cryptococcosis usually begins as a respiratory infection in humans, and may eventually spread to the central nervous system.

Avian tuberculosis (AT) is another disease that causes considerable frustration for dairy farmers. As the name implies, avian tuberculosis is a disease that occurs primarily in birds, but many also occur in pigs. AT is worldwide in distribution, but occurs most frequently in the northern temperate zone, It generally causes no lesions, or only nonprogressive lesions in lung lymph nodes in cattle. In rare cases AT can cause generalized progressive lesions in cattle. It may also cause mastitis. AT is a more common infection in domesticated fowl than in wild birds, but both are susceptible, and where wild and domestic birds intermingle, the bacteria is easily transferred. AT may be transmitted through direct contact with feces, consumption of feed contaminated with bird droppings, or through inhalation.

The major AT problem for the dairy farmer isn't the disease itself, but rather the caudal (tail) fold tuberculosis test, the official surveillance test for tuberculosis. This test cannot distinguish avian tuberculosis from bovine tuberculosis, because both cause a swelling of the tail. If this initial test is positive, the farm is usually quarantined because of the serious risk of infection to humans and other cattle, if bovine tuberculosis were actually present. This quarantine can last from 10 days (most common) to 6 months or more, depending on additional test results. Occasionally these additional tests are inconclusive, requiring that indemnity be paid, and the animal be taken for necropsy and pathological examination. Certain acid-fast soil bacteria may also cause cattle to react positive to a caudal fold test.

In Vermont, for example, there has been no instance of bovine tuberculosis in cattle since 1982. However, there are an average of 156 false positives to the caudal fold test annually, because of AT, all requiring some period of quarantine. Approximately 9 cows are taken yearly for diagnosis via necropsy.

Other diseases associated with pigeons, starlings, and house sparrows that may infect cattle include: erysipeloid, listeriosis, paratyphoid, pastiurellosis, streptococcosis, yersiniosis, vibriosis, aspergillosis, candidiasis, coccidiosis, sarcosporidiosis, toxoplasmosis, trichomoniasis, chlamydiosis, Q fever, meningitis, taeniasis, and schistosomiasis. Many of these may cause mastitis, abortion, or a decrease in milk production in cattle. Most are also transmittable to humans.

When attempting to alleviate sanitation and health problems caused by large concentrations of pigeons, house sparrows, and starlings, three important factors must be considered: timing of control, persistence in carrying out control, and diversity of control methods. While pigeons and sparrows may roost in barns overnight, starlings usually form large flocks that roost in nearby stands of brush or trees. The largest numbers of birds are usually present in barns during the winter, when cold weather causes them to seek shelter and alternative sources of food and water. Proper identification of all bird species present is important before any control techniques are implemented. Most birds are protected by federal laws. However, pigeons, starlings, and house sparrows are NOT protected by federal laws.

One approach to controlling birds is exclosure and habitat modification. Some bird problems can be reduced by excluding the in from buildings. This can often be accomplished by screening or blocking access areas with 1/4 inch wire mesh or netting. Areas such as vents, broken windows, and eaves all provide access for birds.

Another method of habitat modification involves locating the roost sites of starlings, and making them less attractive to the birds. Since starlings often roost in dense stands of trees and shrubs, thinning some of the trees and pruning branches of others may cause the birds to relocate the roost.

Populations of pigeons, starlings, and sparrows may be reduced by destroying nests and eggs. For best results, nest sites should be checked every two weeks for re nesting attempts, and nests should be destroyed before eggs are laid. A long pole with a metal hook on the end is useful for removing nests built in high rafters or ledges. This control method should be used in combination with other control methods, such as exclusion.


In short, birds around dairy barns can be a significant health hazard, for both livestock and people, and the best means of damage control is to use a variety of techniques.

From USDA/APHIS/ADC documents