| Birds: Nests and Young | Nests In and On Buildings There are a number of bird species whose selection of balconies and building ledges or nooks and crannies in houses as nesting sites can sometimes cause conflicts with humans. Most complaints concern the house sparrow, European starling, and Rock Dove (pigeon), all nonnative species.
 On the other hand, there are many bird species whose cohabitation in or on human structures provides enjoyment. The insect-eating chimney swifts, and barn and cliff swallows are just a few examples.
NATIVE SPECIES THAT NEST IN OR ON HOUSES AND BUILDINGS
Chimney swifts build a twig nest using their saliva to glue the twigs together and make the nest adhere to the inside wall of the chimney. Cliff swallows build mud nests under the eaves of houses while 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, although the house finch's favorite location for its nest is in hanging plants or wreaths.
Other birds that occasionally use buildings as nest sites are herring gulls and killdeer, both species prefer flat, gravel roofs. American kestrels, barn owls, and Carolina wrens will use nooks and crannies in buildings, and will enter buildings through openings to build nests on ledges or rafters. In Massachusetts, the peregrine falcon nests in urban locations high on sheltered ledges of buildings.
In most cases, people live in harmony with the species mentioned above and enjoy watching the parental activity at the nest.
UNWANTED NESTS
pigeons, European starlings, and house sparrows habitually use houses and other buildings as nest and roost sites. pigeons seek flat surfaces such as balconies, ledges, windowsills, or rafters. Starlings and sparrows seek more protected locations in dryer vents and holes in eaves or gutters.
IDENTIFICATION
Rock Dove ( pigeon) - A typical pigeon is 12 to 14 inches long with a 17 to 19 inch wing span. There are many color variations among feral pigeons, but the most familiar is bluish gray with black bars on the wings and iridescent feathers of green and purple around the neck. Pigeons have red or pink legs.
European starling - During the breeding season, starlings are predominantly black with pale beige speckles on the back and breast. They have iridescent feathers of purple and green over most of the body and a yellow bill. During the winter, the speckles become much more predominate and the bill is black.
House Sparrow -The male house sparrow is about six inches long with a light gray breast, distinctive black bib, white cheeks, and a gray crown surrounded by chestnut. The wings are a mottled brown with a white wing-bar. The female has a grayish beige breast with a slightly darker back, streaked with shades of brown. It has a buffy eye stripe and light bill.
NESTING BEHAVIOR
Pigeons breed any time of the year, including winter. The female lays one or two eggs, which she incubates for 18 days while the male guards and feeds her. When the squabs (young pigeons) hatch, they are fed a secretion from the mothers' crop called "pigeon milk." By the time the young leave the nest at 4 to 6 weeks, the female may already have laid eggs for the next brood.
Starlings nest in just about any available hole or cavity anytime from early April through July. Four to five eggs are laid in an untidy nest of dried leaves, stems, grasses, and twigs.
Both males and females incubate the eggs for 12 days and rear the young until they leave the nest at 21 days. They are independent of their parents in four to five days. Starlings have two or three broods per season.
House Sparrows commonly nest in holes or cavities in buildings, birdhouses, and trees, as well as protected areas on porches, under awnings, and behind shutters. Nests are built of straw, grasses, trash, feathers, etc. Incubation of 3 to 7 eggs, mainly by the female, lasts 12 days, and young fledge in 15 to 17 days. Sparrows nest anytime between April and September, hatching two to three broods during that time.
The problem of birds' nesting and roosting on houses and buildings can only be solved by making those spaces unavailable or unsuitable for birds. There will always be birds looking for places to nest.
SITUATIONS AND SOLUTIONS
MOVING NESTS
Relocating an active nest is not an option because it usually means death for the young. Birds do not possess the power of reason, if the nest disappears the parents will not go searching for it. It's best to wait until fall or winter to remove nests and exclude birds from buildings.
EXCLUSION
Appropriate time - 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.
MATERIALS
Bird netting, sold in garden centers as fruit tree-netting, is one material that can be used when excluding birds. It is an inconspicuous and flexible plastic that does not corrode or rust and can be used in all locations. Use mesh with openings that are no larger than one-half inch so that small birds cannot pass through and will not get caught making an attempt.
Wood, sheet metal, and cement are good materials to use when converting a flat surface to a slanted surface unsuitable for birds.
NESTS INSIDE HOMES OR BUILDINGS
The first step is to determine where birds are entering the building. Check for broken windows or screens, open vents or ducts, or holes in walls. Encourage the birds to leave the building by using loud noises inside, and then block openings with the appropriate material.
If birds are nesting on rafters or building supports, suspend netting under areas 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, by the length of the doorway. Attach the strips side by side to the top of the opening, overlapping each three inches over the next. People and vehicles are able to pass through, but the strips fall back into place, preventing birds from entering. Many companies that manufacture industrial doors sell and install these doors. Check the yellow pages.
NESTS ON BUILDING OR HOUSE EXTERIORS
Ledges can be sealed off by attaching netting to the wall a few feet above the ledge, draping it over, and securing it below the ledge.
Another option to prevent birds from nesting on flat surfaces such as railings or ledges is to change them to slanted surfaces. Surfaces angled 60 degrees or more do not appeal to nesting birds because the nesting materials placed on the surface will continuously slide off. Use wood or metal to alter the surface.
BIRDS AND THE LAW
All birds are protected by federal laws under the "Migratory Bird Act of 1918," as well as by Massachusetts state laws. It is illegal to destroy, relocate or possess birds, their nests or their eggs. The only exceptions are non-native species: house sparrow, European starling, and pigeon. Trained and licensed wildlife rehabilitators who have passed a federal and/or state-administered test are permitted to care for injured or orphaned wildlife.
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