Birds can have a huge impact on a dairy farm’s profitability if they aren’t controlled.
“For example, starlings consume about 1.8 pounds of feed per month,” says J.W. Schroeder, North Dakota State University Extension Service dairy specialist. “One pound of that comes directly out of the feed bunk. Plus, starlings often consume the more expensive components in the ration, such as protein pellets or grain, and seldom consume the roughage.”
Birds also pose a threat by carrying disease-causing microorganisms and contaminating product areas with droppings, feathers or external parasites such as mites. In a recent study, birds were identified as a carrier of diseases such as salmonella and cryptococcosis, and the campylobacter jejuni bacteria. Cryptococcosis is a fungal disease that pigeons and starlings can spread to livestock; it may result in chronic, usually fatal, meningitis.
Bird populations cause an estimated annual loss of $100 million to U.S. agriculture, according to Charles Lee, an Extension wildlife specialist at Kansas State University. Three kinds of birds – house (English) sparrows, starlings and pigeons (rock doves) – cause the most problems in U.S. livestock facilities because of the amount of feed they eat and their disease-causing potential.
Federal and state regulations protect most blackbirds and other migratory birds. A federal permit is required to take, possess or transport migratory birds for depredation control. But no permit is required to scare or herd blackbirds, cowbirds, grackles, crows and magpies. Federal laws allow people to take control measures, including lethal methods, when these species are “found committing or about to commit depredation” or “constitute a health hazard or other nuisance.”
State permits may be necessary for lethal control on unprotected species such as feral pigeons, English sparrows or starlings. These three species are not protected by state or federal law. Permits are not required to harass most species prior to nesting. However, destroying young birds, eggs or the nest during the active breeding season is illegal.
No one method is best for controlling problem birds around dairies because each situation is different, Schroeder says. Here are some control options:
Live traps: Their large entrances allow birds to enter easily, but birds also can escape if the traps are not monitored closely. Tipping-door traps are effective for small populations. Some trap designs are listed at http://icwdm.org/handbook/birds/bir_e101.pdf.
Repellents: Auditory and visual repellents seldom are effective. Using sticky products (polybutenes) on ledges or beams to discourage roosting is effective for almost a year in buildings. If used outside, dust and other contaminants reduce the products’ tackiness. Repellents include the active ingredient methyl anthranilate (a nonlethal human food additive found in grape flavoring), which is used as coatings on roosting areas or in aerosol sprays in areas that are not too porous. Methyl anthranilate irritates the three main nerves in the bird’s head. These nerves make the birds very sensitive to what they eat, smell and see.
Exclusion and bird-proofing: Hang plastic strips over doorways. These strips allow people and large animals to pass through, but sparrows see them as a solid wall. Some people are experimenting with using large fans to push large volumes of air downward in place of a door. For bird-proofing, close all openings larger than ½ inch. Repair broken windows and screen roof vents, and prevent birds from roosting in the rafters with metal or plastic bird netting.
Habitat modification: Cover feed and water to limit birds’ access to it. Make sure water levels in waterers are low enough so birds cannot perch on the edge to drink. Clean up spilled grain. Keep the area outside of structures clean and weed- and seed-free.
Feed particle size modification: Feed a pellet about 1½ inches in diameter and 3 inches long to keep birds from eating from feed bunks. For more information, visit http://www.berrymaninstitute.org/journal/spring2011/8_Depenbush.pdf.
Frightening: Scaring birds usually resolves a roosting problem. Start when a problem begins to develop. Dedicate enough staff time to conduct the frightening program properly. Vary the location, intensity and types of scare devices. Examples include distress or alarm calls, noise makers, exploders, propane cannons, bright objects, laser beams, eye spot balloons, hawk kites and mylar tape. Pyrotechnics make a loud noise and concussion, along with a visual cue directly into the flock of birds. The pryotechnics are relatively safe to use but can be a fire hazard if used inappropriately. Cattle seldom are frightened by the frightening devices.
Shooting: Shooting air guns or shotguns with small shot has been somewhat successful where permitted. Baiting birds into a long, narrow row improves the mortality rate per shot. Sparrows quickly become wary of a human holding anything resembling a firearm, so shoot from a blind whenever possible.
Toxicants: Avitrol, Starlicide Complete and DRC-1339 are products approved for use in some states. Prebaiting for several days is key to getting good control. Toxicants work best when applied in cold weather with snow cover, which limits the birds’ access to other food sources. Select a site that is protected from the wind and in full sun to get the best results. Add the toxicant after the birds have accepted the prebait and no nontarget birds are present. Depending on the toxicant used, treated birds usually will die in 24 to 36 hours. Toxicants must not be applied so livestock have access to the bait. Dead birds can be disposed of in the trash or manure pit, buried or incinerated, depending on local regulations. Make sure the neighbors and appropriate local authorities are notified because many of the birds will die off-site. The use of toxicants usually is regulated by the state agriculture department, so questions about product labeling, registration status and pesticide applicator licensing should be directed to that agency.
“Generally, you will need to implement a combination of control techniques,” Schroeder says. “Plus, you most always will have better success if you start the control process early before the problem becomes overwhelming.”
He also advises producers to be persistent but patient.
“Successful control operations take time,” he says. “Be familiar with the biology and behavior of the pest species so you know what techniques are most likely to work. Try nonlethal techniques first, but do not be afraid to reduce populations when necessary.”