The most common repellent is a taste or visual deterrent. Woodpeckers, for example, lick the surface of the area they are drilling (pecking) into to create holes or claim their territory. Repellents can be sprayed onto the surface of the area that they are drilling to make the surface taste bad, thus creating an undesirable location to be in. Other birds, such as pigeons or doves, congregate in large numbers. They can be a nuisance in high traffic areas such as department and grocery stores as these areas provide a high place to roost and (usually) ample food access. An avian repellent, used in our Bird Buffer machine, is a natural irritant that attacks the lungs and eyes of the birds flying into the mist the machine creates using the fluid. This repsonse is temporary but, if used consistently and correctly, can cause long-term bird problems to disappear.
Courtesy of Bird-Be-Gone