Improving Habitat for Scarlet Tanagers

General Forest Management Guidelines

The following general guidelines present a strategy for conserving populations of birds, such as the Scarlet Tanager, that depend on mature, contiguous forest throughout eastern North America. These guidelines, combined with the specific guidelines we provide for the Scarlet Tanager, provide a powerful tool for improving forest-bird habitat. Many of these general guidelines were adapted from two recent publications on habitat management in Illinois (Herkert et al. 1993) and Maryland (MD PIF 1997). Those excellent resources contain additional detailed information for these states.

Regional Forest Conservation

• Whenever possible, avoid fragmenting large contiguous forest tracts; these areas have the ability to support the largest number of forest-interior birds and will also be more likely to provide habitat for area-sensitive species. Also, it is much easier to protect existing forest than to "create" new forested areas. The Maryland guidelines suggest that blocks of at least 7,500 acres (3,000 ha) of mature forest should be preserved. In the Midwest, landscapes that remain at least 70% forested tend to minimize adverse effects of fragmentation, especially hampering intrusion by Brown-headed Cowbirds.
• Develop a long-range forest management plan at as large a scale as possible. Plan to designate tracts that will be mature at each stage in the management plan and maintain connections (corridors) between regenerating forests and mature tracts to facilitate repopulation by birds.
• In regions where public lands contain the majority of contiguous or large forest tracts, the most beneficial management strategies for these forests may involve protection or minimal disturbance, to compensate for habitat loss and fragmentation on adjacent lands.

Figure 6. Riparian forests typically have a high diversity of plant species and foods, such as insects and fruits, that combined provide excellent breeding and migratory stopover habitat for many forest-dwelling bird species. Photo by Bill Evans.

Local Forest Conservation

• Attempt to concentrate disturbance (buildings, roads, campgrounds, other development) along the edges and not within the interior of forest blocks.
• In areas with little forest or high levels of disturbance, preserve or restore even the smallest of forest fragments in an effort to provide some habitat for forest specialists and to provide important stopover sites for Neotropical migrants. Riparian bottomlands (along rivers, streams), ravine bottoms, and patches along lakeshores and coastlines are particularly important (Figure 6).
• When managing individual forest tracts for birds, consider the patch's shape, degree of isolation, vegetation structure, age structure, and status of adjacent forests.

Shape of Forested Area

• Attempt to manage for forest shapes that create the least amount of edge. Circular plots are the best at maximizing forest interior, whereas square or rectangular plots are better than long, narrow strips (Figure 7). Circular forest plots offer less access to the interior for predators and nest parasites while maximizing habitat for area-sensitive species. Research shows that area-sensitive species tend to use forested areas that are at least 330 feet (100 meters) from an edge.

Figure 7. The shape of a forest patch affects the amount of edge and forest-interior habitat that is present. Round and square patches have less edge and more forest interior than long narrow-shaped patches. Illustrations by Keila Sydenstricker.

Isolation Effects

• Minimize isolation of forest patches by promoting reforestation of gaps between disconnected forest tracts. Forest birds generally have higher reproductive success in forest that is either connected to or in close proximity to other forest patches. This also facilitates dispersal and territory establishment.

Forest Structure and Age

• Maintain a well-developed woody and herbaceous understory. Many forest-interior birds depend on the cover, food, and nest sites provided by a diverse and well-developed understory. Monitoring or controlling livestock grazing and browsing by white-tailed deer may be desirable or necessary.
• Uneven-aged forests with a well-developed, but broken, canopy usually provide the best habitat for forest birds.
• Where possible, preserve existing old-growth stands and provide for the development of future old growth by leaving areas undisturbed or unharvested for 150 years or more.
• Avoid loss or change in tree-species diversity and fitness by minimizing "high-grading" (the removal of only the most valuable species and the most structurally superior trees).

Reforestation

• Promote reforestation of artificial forest openings, areas surrounding forest peninsulas, gaps between isolated forest tracts, and riparian corridors to create more forest interior for area-sensitive species. Reforestation can be achieved by succession, essentially leaving the area untouched for a number of years, or by planting native trees.
• Avoid planting monocultures, especially of exotic species; these are less attractive to most forest birds. Monitor forested plots for nonnative, invasive plants, and devise a removal plan if necessary.

Work Within Your Community

• Work with your neighbors and adjoining landowners to conserve adjoining forest to maintain contiguously forested areas. Consider creating a landowners association, or work with a land trust or forest manager to produce guidelines for people within your community who wish to maintain the commercial value and ecological integrity of their forests. Take part in your state or regional Partners in Flight Working Group (see regional summaries section).