Nests In & On Buildings
A number of bird species nest on balconies and building ledges or in the nooks and crannies of houses. Observing these nests can be a source of enjoyment, and native species that eat insects, such as chimney swifts, barn swallows, and cliff swallows, help with pest control.
Sometimes, however, nesting behavior can bring birds into conflict with people. This is often the case with the nests of non-native species such as pigeons, European starlings, and house sparrows.
Moving Nests in Undesirable Locations
Relocating an active nest is not an option. Birds do not possess the power of reason, if the nest disappears the parents will not go searching for it. It is also against both federal and state law to disturb the nest of a native species. The only exception would be nests of the non-native house sparrow, pigeon, and European starling. It’s best to wait until fall or winter to remove nests and exclude birds from buildings.
To determine whether the young have fledged and it’s safe to block the opening, monitor the nest each day. After the eggs hatch, you’ll see the parents make frequent trips back and forth to the nest site and you’ll hear loud chirping from the young. In two to three weeks, depending on the species, the young will leave the nest and the noise and activity will stop.
Excluding Nests Inside Buildings
Once the young are gone, figure out how the birds are entering the building. Encourage adult birds to leave the building by using loud noises inside, and then block openings with the appropriate material.
If birds are nesting in a cavity, it’s important to block the opening immediately after the young birds leave, because the adults will likely return in a day or two to begin another brood. Securely block the opening with hardware cloth, metal, or wood. Bird netting, sold in garden centers as fruit tree netting, is another option. It is an inconspicuous and flexible plastic that does not corrode or rust. Be sure to only use mesh that has openings no larger than one-half inch across, so that small birds cannot pass through and will not get caught making an attempt.
If birds are nesting on rafters or building supports, suspend netting to create a false ceiling that will prevent birds from entering those spaces.
To prevent birds from entering buildings through loading dock doors or garage bays, use large sheets of heavy plastic to create a barrier. Cut the plastic into strips 12 inches wide and as long as the doorway is tall. Attach the strips side by side to the top of the opening, overlapping each one three inches over the next. People and vehicles will be able to pass through, but the strips will fall back into place, preventing birds from entering. Many companies sell and install heavy duty industrial strip doors for commercial properties.
Excluding Nests on Exterior Flat Surfaces
You can seal off a ledge by attaching netting to the wall a few feet above it, draping it over the space, and securing it below the ledge. Another option is to change a flat surface into a slanted one. Surfaces angled 60 degrees or more do not appeal to nesting birds because the nesting materials placed on the surface will slide off. You can use wood or metal to alter the surface.
Excluding Non-Native Species
Sparrows and starlings begin nesting in April or May and have two or three broods during the course of the season. It is impossible to know when a female bird has laid her eggs, and therefore it is impossible to determine when the young will leave the nest.
Monitoring the nest each day is the only way to determine when the young have fledged and it is safe to block the opening. After the eggs hatch, the young are fed by the parents and their frequent trips back and forth to the nest site can be observed and loud chirping can be heard from the young. In two to three weeks, depending on the species, the young leave the nest and the noise and activity stop.
It is important to block the opening immediately because the adults will likely return in a day or two to begin another brood. As soon as there is no more activity at the nest site securely block the opening with hardware cloth, metal, or wood.
Types of Nests
Nests of Native Species
In most cases, people live in harmony with nesting native species. Here are a few common species that nest in and around houses:
- Chimneys are popular places for chimney swifts to nest. Learn more about chimney swifts
- Cliff swallows build mud nests under the eaves of houses. Barn swallows build cup nests of mud pellets, grass, and feathers, high on rafters and ledges in barns, garages, or any building that offers access.
- Light fixtures and ledges under porches and decks provide nest sites for eastern phoebes, American robins, and house finches.
- Flat gravel roofs are common nesting sites for herring gulls and killdeer.
- Nooks and crannies in buildings may house American kestrels, barn owls, and Carolina wrens. They will enter buildings through openings to build nests on ledges or rafters.
- Sheltered ledges in high places are nesting sites for peregrine falcons.
Nests of Non-Native Species
Pigeons, also known as rock doves, are originally from Europe, Africa, and Asia. Our pigeons are the escaped descendants of domesticated birds. They build simple twig nests on flat surfaces such as balconies, ledges, windowsills, or rafters. They breed at any time of the year, including in winter. The female lays one or two egg and incubates them for 18 days while the male guards and feeds her. By the time the young leave the nest at 4 to 6 weeks, the female may already have laid eggs for the next brood. Learn more about pigeons
European starlings are native to Europe and Asia. They nest any time from April through July, and seek more protected locations for nests, such as in dryer vents and holes in eaves or gutters. Their untidy nests are made of dried leaves, stems, grasses, and twigs. Males and females cooperate to incubate the eggs for 12 days, and the young leave the nest in 21 days. Starlings have one or two per season. Learn more about European starlings
House sparrows are native to Europe and Asia. These small birds commonly nest in holes or cavities in buildings and trees, as well as in protected areas on porches, under awnings, and behind shutters. They use a variety of materials to build their nests, including straw, trash, and feathers. Females sit on the nest for 12 days and the young are ready to fly in 15 to 17 days. They nest any time between April and September and hatch two to three broods. Learn more about house sparrows
Birds & the Law
Many of the birds and animals we encounter are protected in some way by local and national laws. Learn more