There are electrical and electronic devices that are designed to repel unwanted birds and animals without causing physical harm to the unwanted pest. These methods of pest deterrence are not a foolproof, magical solution, but they can be quite effective when properly used in a sensible manner.
Besides the usual "I just don't like them, they bother me" reasons for not wanting those pesky birds and animals around, there are very real health and other concerns associated with their presence.
This is not to say that all birds and animals present great dangers to human life and health, but only that there are risks associated with their presence when they are not properly cared for and kept under human supervision and control. A few Pigeons or Seagulls in the park are not a serious health hazard, but the same birds, when nesting on a roof or in a building ventilation system, can be a cause of dangerous or deadly conditions. As in all things, it is wise to gain a good understanding of the dangers as well as the benefits that may result from any situation or event that may affect us.
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The most common electronic method of discouraging birds and animals from staying in any area involves making sounds that are unpleasant to them.
The hearing of these creatures can be very different from that of humans and also very different for different species. This makes it possible to electronically generate sounds that will be unpleasant to some and not to others.
For example, high - frequency sounds (ultrasonic sounds) cannot be readily heard by most humans while some other species can hear them. Dog whistles are a good example as they can be heard by dogs, but not by most humans. Bats are known to guide themselves by listening for reflections of the high - pitched sounds they make while flying, similar to guidance systems (sonar) on submarines.
Ultrasonic sound generators are used to repel bats and rodents as well as other very small pests. The constant electronic sounds are thought to disturb and confuse them by affecting their ability to navigate and detect danger. Most times, they will leave the area and go to a quieter place.
Its similar to living in front of the speaker stacks at a rock concert. The sound might not kill you, but you would probably look for some other place to eat and sleep.
Another way to repel some pests is with recorded distress calls.
To explain, suppose you lived in a place where, at unpredictable intervals, blood - curdling screams would ring out, as if from someone being tortured and torn slowly into little pieces. You would almost surely feel safer elsewhere, and you certainly wouldn't want to bring up children in such a place.
This works very well to discourage some types of birds and not so well, or not at all, for others. For example, while Seagulls respond well to these types of deterrents, Pigeons don't seem to care at all.
Usually, when a distress call is played, the species that recognizes the alarm will come to investigate the cause of the disturbance. After awhile, they will all leave the area and stay away from the unseen source of danger. Other species sometimes react to these distress calls as well, and move away from the source of discomfort, but that reaction is less predictable.
Playback of recorded calls of predators can also serve to create an area that some species of birds will tend to avoid. It's the electronic version of the plastic figures (such as Owls) you may have seen on the rooftops of some buildings. The difference is that the pest birds are not as likely to get accustomed to the noisemaker in the same way as they do the statues, which seem to lose their effectiveness when the birds learn to perch on them.
Generally speaking, electronic pest control devices such as these are clean, effective, and safe, and can be deployed by almost anyone.