Guidelines for Protecting Migratory Bird Habitat
To survive, birds need habitat. Exactly what type and how much depends on each species’ food preferences, foraging strategies, and nest site requirements. Some kinds of birds do fine in suburban and even urban areas. But species whose habitat requirements are specific — in particular, birds that require large tracts of woodland or grassland – are having more difficulty. For example, the Swainson’s Warbler, a bird of southeastern bottomland hardwood forests, requires about 25 acres of habitat per breeding pair. And a single pair usually will not nest unless other pairs inhabit the area, too. Maintaining a viable population of these birds requires a forested tract of perhaps 5,000 acres.
For species with specific habitat requirements, we must maintain suitable habitat in the face of human activity. And the challenge is heightened by the fact that unlike humans, birds do not pay attention to land ownership. Because their habitats cross legal boundaries, habitat protection plans must too.
Is protecting habitat for migratory birds a realistic goal for the 21st century? You bet! Many amateur birders, conservationists, agency personnel, and private landowners support conservation of bird populations and their habitats before species reach critically low levels — at which point intervention becomes expensive and controversial. Maintaining habitat can and does occur on the local, state, regional, national, and even international levels.
To be successful, habitat maintenance should follow several guiding principles. These can be applied to conservation of breeding range, wintering grounds, and migratory corridors. All land managers, public and private, should find these principles helpful in guiding their thinking about how to enhance habitat.
As you go about your migratory bird conservation projects — whether in your own backyard or in a wider community – review these principles from time to time. They will help keep your project on track.
Guidelines for Backyard Habitats
- Grow native plants that provide fruit or seeds.
- Woodlots with fallen limbs and leaves, dead plant material, and other woodland debris harbor the insects that migratory birds thrive on. Leave as much dead plant material as possible on the land (without endangering your home, of course).
- Seek alternatives to chemical pesticides. Use biological controls for unwanted insects and vegetation.
- Reduce the risk of bird predation by keeping pet cats indoors. Refrain from putting out table scraps, which will attract predators such as raccoons.
- Invite neighboring landowners to join your backyard effort. Plan cooperatively!
Guidelines for Conservation of Migratory Birds on Grasslands
- Avoid fragmenting existing grassland tracts. The larger the grassland, the greater the number of area-sensitive species, such as Upland Sandpiper and Henslow’s Sparrow, that will be able to nest successfully in the area.
- When restoring grasslands, minimize the amount of edge habitat by designing roughly circular or square plots. Such programs should use native grasses and local seed sources. Determing the species that should occur at a given site may require research.
- To benefit area-sensitive birds, we believe that plots should be no smaller than 125 acres, and preferably 250 acres or more. Fifty acres or less will benefit birds that are the least sensitve to area size (such as Dickcissel or Red-winged Blackbird).
- If plots smaller than 50 acres are the only option, we recommend that they be as numerous as possible and no farther apart than one mile.
- Monitor grass height. Eliminate woody vegetation that grows higher than native grasses.
- Grassland evolved with regular burning. Learn about prescribed burns and evaluate the possibility of instituting this practice.
Guidelines for Conservation of Migratory Birds in Forested Areas
- Avoid fragmenting forested areas.
- Maintain a well-developed understory, including woody and herbaceous vegetation, to provide resources to a diverse set of woodland bird species.
- Minimize the amount of edge habitat by managing generally circular- or square-shaped forests.
- Protect or restore forests along streams, wide stream bottoms, and ravines — they can be crucial to migratory birds.
- Remove nonnative plant species, such as kudzu and salt-cedar.
Guidelines for Conservation of Migratory Birds on Farmlands
- After harvest, leave crop residue on the soil surface. This residue supports insects that are crucial to the diets of migrants and provides cover during inclement weather.
- Use biological controls on crop pests. Integrated pest management systems that achieve this end include establishing permanent vegetative cover on steep hillsides, reducing the frequency and intensity of tillage, and rotating crops over several years. These techniques reduce the need for chemical pesticides and fertilizers and ensure that only the target pest insects are destroyed.
- Postpone spring mowing as long as possible avoid mowing at night, and make intervals between mowings as long as possible to give birds the best chance for successful nesting.
- Use inorganic fertilizers sparingly; base use on accurate soil requirements.
- Do not mow fencerows and other uncultivated areas or spray them with pesticides. Try to carry out field operations in these areas only before or after nesting season.
- Leave wooded corridors of shrubs or standing trees between fields.
- Preserve uncultivated areas and allow them to develop into a variety of vegetative types. Areas between crop fields are helpful to migratory birds. Also, they can help reduce soil erosion.
- Use farmland in a wide variety of ways.
- Maintain grassy strips within cultivated fields to provide nesting and feeding areas of grassland birds.
- Preserve wetlands by buffering them with wide zones of natural vegetation.
Guidelines for Conservation-oriented Land-use Planning
- Don’t overlook small habitat patches — even small plots of trees, shrubs, or grasses are used by migrating birds, and maintenance of these areas should be encouraged.
- Development should take into account the needs of migratory birds:
- During construction, destroy as little natural habitat as possible. (Not only is this helpful for birds, it often increases the value of homes.)
- Avoid placing structures on ridge tops. Bird tend to follow ridges during migration. Structures built along these routes pose serious threats — every year, millions of birds are killed when they strike windows, power lines, and towers.
- Avoid placing structures within adjacent to wetlands. Wetlands are particularly important to migrating birds because of the abundance of food and cover.
- When building along a known flight path, consider the orientation of the structure. If possible, place houses so that large windows do not sit perpendicular to the flight path (in most places, north and south). Elevated telephone lines can also cause problems along flight paths.
- Community plans should include tracts of native habitat. Cluster housing, that is, localizing homes within large tracts of land, is a helpful technique for achieving this goal.
Bushman, E.S., and G.D. Therres. 1988. Habitat Management Guidelines for Forest Interior Breeding Birds of Coastal Maryland. Technical publication summarizing habitat requirements and the impacts of various habitat alterations for 19 species of forest-interior-breeding birds. Available from Glenn D. Therres, Maryland Department of Natural Resources, P.O. Box 68, Wye Mills, MD 21679. (410-827-8612).
Faaborg, J., M. Brittingham, T. Donovan, and J. Blake. 1993. Habitat Fragmentation in the Temperate Zone: A Perspective for Managers. In Finch, D., and P. Stangel, eds. Status and Management of Neotropical Migratory Birds (see Citizen’s Guide page 8 for full reference).
Rodenhouse, N., L. Best, R.O’Connor, and E. Bollinger. 1992. Effects of Temperate Agriculture on Neotropical Migrant Landbirds. In Finch, D., and P. Stangel, eds. Status and Management of Neotropical Migratory Birds (see Citizen’s Guide page 8 for full reference).
Hamel, P.B. 1992. Land Manager’s Guide to the Birds of the South. The Nature Conservancy, Southeastern Region, Chapel Hill, N.C. Designed to be used by land managers as a guide fo revaluating and prescribing land management practices. 437 pages. Available for $20 from The Nature Conservancy, P.O. Box 2267, Chapel Hill, NC 27515-2267.
Herkert, J., R. Szafoni, V. Kleen, and J. Schwegman. 1993. Habitat Establishment, Enhancement and Management for Forest and Grassland Birds in Illinois. Illinois Department of Conservation, Natural Heritage Publications #1 (see Citizen’s Guide page 8 for full reference).