The field of the present invention is mechanical devices and methods for deterring birds from landing at undesirable perch locations. Historically, birds have been a constant pest to all types of structures and activities of man. Particularly troublesome are areas with large populations of swallows, seagulls, and pigeons although other species such as starlings, sparrows, swallows and blackbirds create problems. These unwelcome birds create unwanted noise and their droppings are an unsightly testimony to their presence on public structures and private residences. The bird droppings can also present a threat to human health. Fungi in these bird droppings can transmit diseases to humans, with potentially fatal consequences to those suffering from diabetes, blood diseases or a respiratory disease.
A particular problem is the narrow ledges common in our urban areas. Numerous methods and devices have been utilized to keep birds away from these areas where the birds are known to roost and subsequently build their nests. Several methods have utilized inanimate devices comprised of a continuous metal strip or spine with sharp, protruding spikes. However, to be effective, these must be accurately placed on the nesting area. Also, this device is conducive to nest building by the more industrious of the bird pests, due to its immobile character. Such devices may be injurious to the birds that impale their wings onto the sharp spikes. These devices are also potentially injurious to humans who unknowingly venture too close. These devices are also surprisingly expensive. Also, leaves become impaled on the pointed spikes, decreasing their effectiveness. Others have tried certain chemical gels that are applied to the perching area giving the perching birds a chemical hot foot. These, however, have a limited life span, as the gel collects debris, rendering it ineffective and, to no one's surprise, the gel eventually wears off the perching area. Mock predators have been used, but these eventually lose their deterrence effect. After a short time period, pigeons will sit quite comfortably atop these "artificial adversaries." It is noteworthy that none of these bird deterrents display the erratic motion which especially frightens the birds.
Another popular device is an electrified wire draped strategically around the nesting or perching area of the birds. These have been used at public buildings, but their high installation cost prohibits use at residences or smaller public facilities. Also, there is the constant cost of keeping the wires electrified and the potential for injury to humans.
Noise deterrent devices have been used but these also annoy the human occupants of the building or residence. Ultrasound emitters effectively deter birds but also household pets, such as cats and dogs, and thus are not real solutions. Another device emits an intermittent flash of light that is disruptive to the birds. This device is ineffective for exterior areas during daylight hours and requires constant upkeep.
Others have employed real life predators such as peregrine falcons to get rid of the bird pests. These are unreliable over the long run as the predator may do away with small dogs, cats and anything else seen as potential prey. Also, they do not address the problem of the offensive mess left by the predator itself. Still others have employed the particularly offensive method of shooting large numbers of the offending birds only to have others replace the killed pests.
Reference is made to U.S. Pat. No. 4,841,914 for "Method and Apparatus For Deterring Birds" issued to V. Chatten illustrating an inanimate bird deterrent. Reference is also made to a pending application entitled "Mechanical Apparatus for Deterring Birds," Ser. No. 07/475,215, filed Feb. 5, 1990, and to a Continuation-In-Part of that application entitled "Methods and Apparatus for Deterring Birds", Ser. No. 07/523,744, filed May 15, 1990. These illustrate an animated bird deterrent device. The aforementioned patent and patent applications are hereby incorporated by reference herein.
In view of the foregoing, a need has arisen for a bird deterrent device that is effective on narrow building ledges which combines the best features of the inanimate devices with the best features of the movable devices and behaves in an erratic bird deterring fashion. It must be adaptable to public buildings and private residences, be relatively inexpensive and easy to install, and not be injurious to the birds or offensive or injurious to humans.