Keep birds from nesting on a deck or porch by using a non-lethal bird deterrent such as a mirror, plastic hawk or bird netting. There are federal and local ordinances protecting birds, their nests and their eggs, making it illegal to kill or destroy them.
Put small mirrors in the corners of the deck or porch where the bird is likely to nest. The reflective properties of light and shadow make it less likely for the bird to choose to nest in that location. Hanging reflective bird deterrents are available for purchase. In addition to the reflective mirror properties, they include appliqu�s that look like predators' eyes and frighten birds away from the area.
A plastic hawk is another predatory nesting deterrent. Place the hawk on the corner of the deck to prevent nesting. Periodically, move the hawk to a different location on the deck to prevent the birds becoming accustomed to it. A bird spider is also effective in scaring away birds from nesting. The bird spider has a solid base and stainless steel arms that spin around in the breeze. This threatening display discourages birds from building.
Bird netting is an effective way to deter birds from open rafters above and below the deck. Use a staple gun to attach the netting and keep the birds from reaching these common nesting areas.