Dickinson Ch25: Bird Communities of Southern Forests

Bird Communities of Southern Forests

I. General Importance and Context

• Indicators of Health: Birds are a high-profile group for wildlife watching and are crucial indicators of habitat conditions and environmental health. Monitoring bird ecology is necessary for managing game and non-game species.

• Southern Abundance: The temperate climate and diverse forests across the Southern U.S. support diverse and abundant communities of breeding, wintering, and migrating birds.

• Declines and Threats: Historical human land use has led to declines, especially for species associated with old-growth forests. Extinct or precariously close species include the Carolina parakeet, passenger pigeon, ivory-billed woodpecker, and Bachman's warbler.

• Major Conservation Concerns (Recent Decades): Conservation concerns focus primarily on (1) nearctic-neotropical migratory birds and (2) grassland birds.

  • Declines in neotropical migrants are often linked to reduced breeding/wintering habitat quality, competition, predation, and exposure to environmental degradation (e.g., acid rain, global climate change).

II. Factors Determining Bird Communities

• Habitat Determinants: Bird species distribution and community composition are determined by landscape and stand scale habitat conditions.

• Stand Characteristics: Primary factors influencing species occurrence and abundance include foliage layers, volume, habitat patchiness, stand successional stage, diversity of forest type, and stand structure.

• Pine Stands: Within pine stands, the hardwood component is the primary determinant of the bird community composition.

• Stand Structure Change: Changes in forest stand structure (e.g., from dense early-successional to closed-canopy late-successional) significantly influence which species are present.

III. Priority Habitats and Species

• Partners in Flight (PIF) Process: The PIF Priority process helps focus conservation efforts using criteria like relative global abundance, population trend, and area importance.

• Early-Successional Forest and Shrub-Scrub:

  • These habitats, often reliant on disturbance, support species grouped into grassland, early-successional shrub-scrub, and southern pine types.

  • Species like the Prairie Warbler benefit from management that includes fire, which creates shrubby, grassy habitat.

  • The Golden-winged Warbler (Southern Appalachians subspecies) and the Bewick's Wren (Appalachian subspecies) have experienced drastic population declines.

• Southern Pine Forests and Pine Savannas:

  • Red-cockaded Woodpecker and Mississippi Sandhill Crane are federally endangered species dependent on southern pine systems.

  • Many high priority pine species, such as the Bachman's sparrow and Northern bobwhite, depend on abundant grass and herbaceous ground cover, often maintained by fire.

  • Appropriate longleaf pine stands, often mixed with shortleaf pine, provide quality habitats, supporting species like Bachman's sparrow and the red-cockaded woodpecker.

• Forested Wetlands and Riparian Areas:

  • These are critical for breeding and wintering neotropical migrants. Habitats include tupelo-cypress, bottomland hardwoods, and swamps.

  • The Cerulean Warbler is a neotropical migrant with a precarious status, requiring large tracts (10,000+ acres) of mature forested wetlands.

  • Swainson's and Prothonotary Warblers are priority wetland-associated species requiring dense understory foliage/aquatic invertebrates.

  • Riparian forests (streamzones) are important travel corridors for migrating birds.

• Upland Hardwood-Pine Forests:

  • These mixed forests occur primarily in the Piedmont and Gulf Coastal Plain.

  • Many breeding birds in these areas show decline trends. Retention of later-successional hardwood-pine stands is a primary conservation goal.

• Appalachian Forests (High Elevation):

  • Management requires attention to forest composition and structure.

  • Hemlock-White Pine-Hardwoods and Spruce-fir forests support specialized northern bird populations (e.g., Northern Saw-whet Owl, Black-throated Blue Warbler).

IV. Management Recommendations

General management recommendations for southern forests include:

1. Maintaining and restoring the health of spruce-fir and northern hardwood forests.

2. Conducting public and corporate planning using comprehensive plans.

3. Developing conservation partnerships targeting key species like the golden-winged warbler and cerulean warbler.

4. Promoting appropriate silvicultural operations, such as cuttings of hardwoods and uneven-aged management.

5. Prioritizing research, monitoring, and ecostystem management.

6. Managing forests to support important diversity components, such as diverse age structure and vegetative layers (understories, seedlings).

7. Restoring specialized habitats like pocosins and Atlantic white-cedar.

8. Optimizing stream-side zone widths for breeding and feeding. Narrow zones (less than 150 feet) are adequate if adjacent lands are dominated by mature/natural forest. Wide zones (at least 300 feet) are necessary when adjacent lands are developed or agricultural.

Conclusion:

Understanding the bird communities of the Southern Forests is like trying to manage a complex library with interconnected archives: not only do you need to protect the oldest, most valuable volumes (old-growth species like the Red-cockaded Woodpecker), but you also need to manage the dynamic circulation section (early-successional habitats) and ensure the pathways (riparian corridors for migrants) remain clear and intact.