Habitat Establishment, Enhancement and Management for Forest and Grassland Birds in Illinois

Management Guidelines For Forest Tracts

Avoid fragmentation of existing contiguous forests. The preservation of existing forest land is the most effective means of maintaining populations of forest-interior species and is much easier than creating new forested areas.^31,32 Forest tracts that support species with high or moderate area-sensitivity (Table 2) should receive the greatest protection.
Maintain a well developed woody and herbaceous understory in all forested tracts. In degraded forests promote the redevelopment of a diverse understory by removing livestock³³, halting mowing, and attempting to control over-browsing by white-tailed deer. Many species of forest birds require the food, nest sites, and cover provided by the forest understory.
Manage for forest units that approach a circle or square in shape to maintain the maximum amount of forest with the least amount of edge. Woodlands of this shape are much more effective in maintaining populations of forest-interior birds than are long, narrow ones. The parts of a forest that are most beneficial to species with high or moderate sensitivity to habitat fragmentation (Table 2) may be more than 110 yards (100 meters) from the forest edge.¹⁴
Preserve and/or restore forest sections bordering streams, and wide stream bottoms and wooded ravine habitats, because these areas are particularly valuable for forest birds.³⁴
Promote the reforestation of existing artificial forest openings, open peninsulas, and gaps between isolated forest blocks in order to create larger and more valuable forest blocks for area-sensitive species. Reforestation can be achieved through natural succession but is more efficiently achieved through planting of native trees. Many opportunities exist for reforestation of open peninsulas or forest gaps in Illinois' forests associated with steeply dissected uplands. Many small and/or narrow ridge top fields occur in such areas (Figure 4).

Figure 4 - Reforestation strategies for enlarging forest habitat for birds that are sensitive to habitat fragmentation. The areas shaded yellow are upland areas that could be reforested to fill sections of the woodland that were cleared for agriculture. The green shaded areas are bottomlands that were also cleared for agriculture but also could be reforested to enlarge the existing forest area and to protect the stream that is adjacent to the reforestation area.
Plan cooperatively with adjacent landowners to maximize unfragmented areas and to maintain or enhance large contiguous forested areas. Consider forming a landowner's association or the development of cooperative management agreements, development restrictions and covenants to protect the forest integrity.
If timber is to be harvested from a forest tract, single-tree selection is the recommended cutting practice. Single-tree selection mimics natural tree fall dynamics³⁵ and may even benefit gap dependent forest species such as the Hooded Warbler.³⁴ Single-tree selection results in the maintenance of the largest area of contiguous forest without the undesirable fragmentation caused by other types of timber harvest. Avoid clear cutting and large group selection cuts (Figure 5a). Group selection cuts as small 1/4 acre have the potential to increase nest parasitism and nest predation rates because they maximize edge habitat.²⁰
When single-tree selection is not possible, owners and managers of large tracts should use a uniform plan of rotation cutting so that the oldest sections are next to each other and the younger stages are adjacent to themselves (Figures 5b and 5c).

Figure 5 - Forest Management Strategies for the maintenance and enhancement of sensitive forest bird populations. Figure modified from Robbins.⁶⁶
Forests Managed for Timber Production
a. Single-tree selection, the recommended harvest strategy for timber producing forests--best harvest method for the maintenance of forest bird populations.
b. Even-age management with a long rotation cycle--less desirable than single-tree selection cutting but preferred over the following two options. Maintenance of a permanent core area and keeping older successional stages adjacent to each other lessens negative impacts on forest-interior bird populations.
c. Even-age management with a long rotation cycle without a central core area--a third-choice alternative that maximizes benefits of older successional stages by keeping them adjacent to one another.
d. "Checkerboard" management should be avoided. It causes severe habitat fragmentation and leads to the loss of area-sensitive species.
Forests Managed for Wildlife Enhancement
e. Broad forest connections prevent the isolation of forest tracts and excessive edge.
f. Planting of native trees in forest openings and expanding and connecting existing forest stands improves habitat.
In long-range timber management plans for large forests, designate tracts that will be mature or nearly mature at each stage in the management plan, and design management operations so that bird repopulation of disturbed areas can proceed via wooded connections or over the smallest possible gaps in mature or nearly mature forest habitat.
In timber harvest areas where mature forests are limited, preserve one or more mature tracts to serve as sources of avian repopulation for developing areas. Ideally, these mature tracts should be at the center of the management unit.
In managed areas where mature and standing dead trees are rare (less than 1/acre), nest boxes for cavity nesting birds can be beneficial. Plans and instructions for building and locating nest boxes for a variety of bird species can be found in the publication "Wood Projects for Illinois Wildlife," available from the Illinois Department of Conservation, Division of Natural Heritage. Similar "how-to" books are available at many libraries.
In any management program aimed at benefiting forest-interior birds and including public use, encourage public use within the forest edges rather than permitting activities to extend into the center of the area. During the nesting season (late April through early August), keep disturbances such as camping, picnicking, or cutting to a minimum, especially in the forest interior.
Avoid construction projects, such as roadway development or improvements, impoundments, transmission line corridors, sewer lines, and other land clearing, that reduce forest area or increase forest isolation. In forests being managed for nongame forest birds, avoid disruptive effects, such as the creation of small ponds or clearings, which increase edge, reduce overall forest acreage, and are likely to be detrimental to forest-interior species.^9,11
If forest loss cannot be prevented, avoid forest management activities during the nesting season (late April through early August). Mitigation plantings should be planned and implemented as far in advance of forest loss as possible. Mitigation plantings designed to enlarge existing forested areas will be the most beneficial for forest bird species.
Eliminate or reduce cowbird feeding opportunities (short grass, bare ground, pastures, feedlots, campgrounds) near woodlands being managed for forest birds. Do not mow roadsides in large forest tracts, or at least keep roadside vegetation at a height of 6 to 9 inches or more to reduce their suitability as cowbird feeding areas. Revegetate logging roads to reduce cowbird feeding opportunities.³⁶
Although many forest bird species are restricted to large woodlots for nesting, even small (3-5 acre) woodlots may be tremendously important as migratory stopover sites for forest-interior bird species, especially in regions where forest habitat is particularly scarce.³⁷ Therefore the preservation and protection of even small woodlots can benefit forest-interior species by providing necessary habitat during their critical migratory stopover periods.³⁸

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