Back to the Research	ASNH Research:
	Urban Bird Study in 2003

Backyard Bird Habitat Your Neighborhood Makes A Difference!

by Carol Foss,  Director of Conservation Science

I always used to envision a set of one-size-fits-all recommendations for improving backyard habitat. It included a standard suite of beneficial trees and shrubs and suggested plans for nest boxes of various dimensions. However, when I began walking the streets of Concord at 5:00 a.m., peering into back, front, and side yards to collect data for our urban birds project, it quickly became clear to me that different strategies make more sense in different kinds of neighborhoods. The table accompanying this article provides information about the frequency with which we have found different species nesting in neighborhoods with different development densities. Look closely and you will see many patterns of occurrence. The following information provides suggestions for backyard landscaping in different types of neighborhoods based on what we have learned so far from our field study of urban birds. Urban environment This category applies to downtown areas of cities, village centers with municipal and commercial buildings, and extra-high density residential neighborhoods with an average house-lot size of up to three tenths of an acre. If your neighborhood fits one of these descriptions, your local breeding bird population consists largely of the "urban aliens"-the non-native House Sparrow, European Starling, Rock Dove (domestic pigeon), and House Finch. In this setting you can provide the greatest benefits to native birds by focusing your attention on migrants. Migrating birds become disoriented by city lights and may circle within the lighted area until they drop from exhaustion (for more information about this problem, visit www.flap.org). Once on the ground, they face high risks of predation and starvation because of the scarcity of food and shelter. Backyard and street-side landscaping, as well as riparian buffers and pocket parks, can provide crucial shelter and food sources, enabling migrants to survive and continue their journeys. Evergreens such as yews, hemlocks, and spruces are ideal for providing shelter, as they have dense foliage regardless of the season. Spruce trees also provide familiar habitat for migrating warblers that forage for insects on twigs and needles. On a few mornings in May, biologists found Blackpoll Warblers singing from the tops of nearly every backyard blue spruce in Concord. Flowering ornamentals such as cherries, plums, and crabapples are usually in blossom during the time when many insect-eating migrants are passing through. The blossoms attract abundant insects on which migrating songbirds can feast. Biologists were delighted and amazed to find Ruby-crowned Kinglets, several species of warblers, and even Yellow-bellied Flycatchers busily foraging in flowering trees planted between sidewalks and streets in many residential neighborhoods. A little spring procrastination also can provide important benefits to migrants. Although it is tempting to put the rake in action as soon as the yard is free of snow, all those dead leaves and other winter debris harbor insects and other invertebrates that can help ground-feeding migrants survive. Dark-eyed Juncos and White-throated, White-crowned, Song, Fox, and Tree Sparrows are the most familiar backyard leaf-kickers. If you are lucky, you might attract a towhee or one of the thrushes. Hermit and Wood Thrushes are the most likely species, but I once discovered a Swainson's Thrush busily searching a windrow of dead leaves along a chain-link fence only a few blocks from Main Street in Concord. It is possible to attract native birds to nest in an urban backyard, but the likelihood of success is low unless you have some like-minded neighbors. The native species most adaptable to heavily developed environments include Mourning Dove, American Robin, Gray Catbird, Northern Mockingbird, Chipping Sparrow, and Northern Cardinal. Their home ranges may be as small as one or two tenths of an acre, but when you subtract buildings and pavement, it takes several house lots to provide that much useable habitat. Dense-foliaged evergreen trees provide ideal nesting habitat for all of these species-biologists found a large spruce on a busy corner in Pembroke with active Mourning Dove, robin, and Chipping Sparrow nests all at the same time! Dense hedges of either evergreen or deciduous shrubs also make excellent nesting sites. European Starling Photo by Corel If your neighborhood has an abundance of trees and you don't have House Sparrows and starlings foraging in your yard on a daily basis, you might consider installing a nest box for chickadees or titmice. However, both the cavity-nesting House Sparrow and starling, the "urban aliens," can be detrimental to whatever native species may be trying to breed in the neighborhood, and nest boxes that attract them do more harm than good. Both starlings and House Sparrows will oust native species from nest boxes and even rob nests of eggs or young. Biologists once watched a starling methodically inspect the spaces under roofing tiles along the eaves of a Concord church and fly off with a House Sparrow nestling in its beak! Unless you want to become the local pro-bono handy person, it's a tough proposition to reduce the numbers of these species in an urban neighborhood, where the vast majority nest in buildings. If you know your neighbors well, you could do a survey of loose trim boards and other openings that provide birds (and mammals) with building access and provide friendly suggestions for tightening up homes and garages. After all, in-house resident wildlife isn't particularly healthy for humans or buildings, either! Medium-density residential environment This category applies to urban and suburban neighborhoods and subdivisions with average lot size of three tenths to three quarters of an acre. If your neighborhood fits this description, native species dominate your local breeding bird population, although a few House Sparrows are still part of the mix. Starlings and House Finches are possible, but not a given. Pairs of Mourning Doves, Blue Jays, Black-capped Chickadees, American Robins, and Chipping Sparrows are almost sure to be nesting somewhere within the thirty acres surrounding your house, and American Crows, Tufted Titmice, White-breasted Nuthatches, Gray Catbirds, and Northern Cardinals are reasonably likely as well. In this setting, you are probably close enough to urban lights to experience some migration "fall out." Your neighborhood is likely to be more hospitable than a more urban one, but you can enhance it further by landscaping with migrants in mind, as discussed above. You are also in a position to improve breeding habitat for native species, so think nesting sites as well as food and cover when considering what to plant. White and gray birches are attractive landscaping trees that some people avoid because they have shorter life spans than other hardwoods. Their tendency to die young and decay quickly is an advantage for cavity-nesting birds that can excavate the soft wood that still is protected from water by the surrounding bark. All but one Black-capped Chickadee nest that I have found in a residential neighborhood was in a birch. Plant birches in a corner of the yard where they won't pose a danger as standing dead wood. They will provide the most benefit to birds if you leave them standing until they literally fall down. Chickadees also will use small nest boxes and can be surprisingly tolerant of human activity nearby. Boxes should be placed among trees and shrubs, as open locations are more likely to attract House Sparrows. Nuthatches and titmice also nest in cavities but usually prefer natural sites over nest boxes. Large deciduous trees with natural cavities that develop from knot holes and abandoned woodpecker nest cavities are the most frequently chosen nest sites. Planting shade trees in locations where they can grow to and past maturity without interfering with wires or threatening buildings, streets, or sidewalks is the best long-term approach to providing nesting habitat for these species. Dense-foliaged trees and shrubs are always a good choice for both general cover and nesting sites. Chipping Sparrows and Blue Jays almost always nest in evergreens; robins, catbirds, and Mourning Doves use both conifers and deciduous species. Trellis roses and other prickly shrubs provide especially attractive nest sites for Northern Cardinals. Low-density residential environment This category applies to urban and suburban neighborhoods and subdivisions with average lot size of 0.75 to 2.49 acres. Neighborhoods in this category have a greatly reduced probability of supporting non-native species. Additions to the list of likely native breeders for these neighborhoods include Downy and Hairy Woodpeckers and Eastern Phoebe. The two woodpeckers excavate their own cavities, usually in a dead limb or decaying bole. Hairies particularly favor aspens, which, like birches, grow fast, have soft wood, and are relatively short-lived. Downies often nest in dead limbs of older shade trees. In natural settings, phoebes nest on ledges, upturned roots, and undercut stream banks. The basic requirements are a more or less flat shelf with an overhang. These requirements are easily met by numerous building constructions-carports, open porches, eaves, and curved drainpipes under roof edges. Unfortunately, suburban phoebes often choose nest sites that have a high level of human activity. Incubating birds are frequently disturbed from the nest, and eggs or young get chilled and die. If there are phoebes in your neighborhood, you can create one or more roofed platforms and install them in quieter locations, such as the back of an outbuilding or a side of your home without a door and away from backyard activity. Other species that may nest in residential neighborhoods include: Ruby-throated Hummingbird, Red-bellied Woodpecker, Red-eyed Vireo, Red-breasted Nuthatch, House and Carolina Wrens, Eastern Bluebird, Wood Thrush, Cedar Waxwing, Yellow-rumped and Pine Warblers, Eastern Towhee, Song Sparrow, Common Grackle, and Baltimore Oriole. Some, such as Red-breasted Nuthatch, Yellow-rumped and Pine Warblers, and Common Grackle, need numerous mature pines within their home ranges. Others, such as House Wren and Song Sparrow, are more likely to occur in areas with abundant shrubs and relatively few trees. Red-eyed Vireo, Cedar Waxwing, and Baltimore Oriole nest in tall hardwoods. The observant reader may have noticed that virtually none of the species discussed so far nests on the ground. One reason for their absence is the lack of low cover in most residential neighborhoods to shelter a ground nest. In addition, ground-nesters are among a group of forest birds considered to be "area sensitive," which means that they require a minimum area of contiguous forest in which to nest. Area-sensitive species in New Hampshire include Ruffed Grouse, Least Flycatcher, Blue-headed Vireo, Winter Wren, Hermit Thrush, Scarlet Tanager, and many of the warblers. High densities of predators, including domestic cats, may be largely responsible for their absence in developed areas. Another contributing factor may be the area of forest they need to find enough food for themselves and their nestlings is greater than what is found near most residential neighborhoods. Regardless of the reasons, even the most carefully landscaped house lots and subdivisions do not provide habitat for a significant number of native birds. Backyard habitat helps, but it is not the total answer. Equally important is encouraging your municipal government to protect large areas of forest where populations of interior birds can survive. Some Useful Publications The Urban Tree Book: An Uncommon Field Guide for City and Town. 2000. Arthur Plotnik in consultation with the Morton Arboretum. Three Rivers Press, New York. Selecting Trees for Urban Landscape Ecosystems: Hardy Species for Northern New England Communities. 1994. State of New Hampshire Department of Resources and Economic Development, Division of Forests and Lands, State Forester's Office, Concord, New Hampshire. Backyard Wildlife Habitat in Vermont. 1997. Steve Parren. Vermont Fish and Wildlife Department Nongame and Natural Heritage Program in cooperation with Central Vermont Public Service Corporation. Landscaping for Wildlife. 1987. Carrol L. Henderson. Nongame Wildlife Program-Section of Wildlife, Minnesota Department of Natural Resources. St. Paul, Minnesota. Woodworking for Wildlife. 1987. Carrol L. Henderson. Nongame Wildlife Program-Section of Wildlife, Minnesota Department of Natural Resources. St. Paul, Minnesota. Shrubs and Vines for Northeastern Wildlife. 1974. Technical Report NE-9. USDA Forest Service NE Forest Experiment Station, Broomall, Pennsylvania. Backyard Bird Habitat. 1988. W. Curtis. Countryman Press, Woodstock, Vermont. Some Useful Websites www.nwf.org/backyardwildlifehabitat www.birdwebsite.com/backyard.htm www.umext.maine.edu/onlinepubs/htmpubs/habitats/7131.htm (also 7132, 7133, 7145, and 7151) Your search engine will lead you to many more!