Birds roosting in the eaves of houses cause many problems. Their droppings are messy, the birds may damage property, the nests are often unsightly and birds may carry diseases that can be passed to humans. Getting rid of the birds is a matter of removing their basic needs: shelter, food, water and safety. When you have made the eaves of your house an unsuitable nesting place, the birds will seek a different, more appropriate home.
Hang visual deterrents near the nesting area. Good choices are helium-filled foil balloons, windsocks, balloons with predator eyes painted on them, whirligigs, or long aluminium or shiny strips that will blow in the breeze. Another option is a commercially available scare device on springs with holographic eyes attached, giving the illusion of a moving predator whose eyes follow the birds. Plastic owls or hawks have been shown to be ineffective over time, as the birds grow accustomed to them, but if they are moved every few days, they may help.
Play sonic deterrents such as the bird's warning call followed by a predator's cry or other loud or frightening sounds. Iowa State Extension recommends playing the sounds for ten to fifteen seconds of every minute just as the first birds are nesting for the evening, and then continue until dark. Repeat this procedure nightly until the birds move. Installing a sonic repellent triggered by a motion sensor will keep the birds from becoming acclimated to a sound.
Attach hardware cloth or netting from the edge of the eaves to the wall to block access to the nesting area. However, wait to evict the birds until after the young have learnt to fly so you don't trap a bird in your eaves. Another option is to prevent birds from roosting by installing bird spikes under or on eaves.
Remove food and water sources from the area if possible. Determine what food the problem birds prefer and keep it out of feeders, or eliminate feeders entirely. Cover grain bins and remove plants that bear nuts or berries from the vicinity of the house.
According to Iowa State Extension, birds are more inclined to leave a new nesting site than an established one, so take action as soon as possible for greatest success.