Watching wild birds build a nest and raise their chicks can be an entertaining experience. That experience loses its thrill when the birds begin building nests beneath your deck, making messes, becoming menacing to your family or guests and destroying your home in the process. Several methods are available to prevent this problem.
Visual deterrents are an effective, inexpensive and safe way to keep birds away from decks. Shiny tape strips or CDs strung onto a line then hung up under decks make a flashing light that birds find frightening and unnerving. Hardware stores often carry bird-control laser lights that create flashing, continuous light that startles birds away. Placing decoy animals such as owls, foxes or hawks beneath the deck often cause birds to believe the decoy is a real predator, thus encouraging them to leave. Birds look for secure locations for their nests, so if an area seems unsafe, they are less likely to build there.
Often, openings or damaged areas in a deck are the reason birds find their way beneath a deck in the first place. These small openings must be repaired and sealed so that entrance to the underside of a deck is no longer accessible. This maintenance is best done immediately after summer months when birds breed or just before birds begin to breed in the springtime. If a bird has built a nest beneath your deck and has laid eggs or hatched eggs in the nest, the best option is to leave the bird and her young alone until the chicks are raised and leave on their own. Repairs may be made to the deck at that time. Touching active bird nests is illegal and should only be done by bird care specialists. Nests with no eggs or chicks may be torn down, though birds often rebuild, so repairs to the deck must be done immediately to prevent this.
If you cannot make repairs to block birds from the deck, physical controls often do the trick. Bird spikes are small, harmless, thin spikes made of metal. These spikes can be placed in strips along beams or other areas birds may try to roost beneath decks. The spikes cause no injury or physical pain to birds but make them uncomfortable when they perch. Eventually, birds grow tired of this and leave. Temporarily installed bird netting also keeps birds from under decks. Simply place the netting over openings you see birds using to gain access to the underside of your deck to prevent problems.
Audio bird repellents come in varieties humans can hear and varieties humans cannot hear, both being equally effective in controlling birds. Simply place the deterrent near or beneath your deck to produce sounds that repel birds. Some types of bird repellents reproduce the sounds of angry birds, predatory birds or birds in distress causing other birds to stay away from the sounds. Ultrasonic repellents make sounds only at frequencies birds can hear. These frequencies are irritating to birds and encourage birds to avoid the area producing the sounds.