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

Management Guidelines for Grassland Areas

Avoid fragmentation of existing grassland areas. The preservation and proper management of existing grassland areas, especially those presently used by area-sensitive species (Table 2), is the most effective means of conserving nongame grassland birds. In areas where existing grasslands are scarce prairie plantings can be very beneficial.
Grassland restorations aimed at benefiting bird species that are most sensitive to grassland fragmentation (Table 2) should be at least 125 acres and preferably more than 250 acres in area. Smaller plantings less than 50 acres will benefit grassland bird species least sensitive to habitat fragmentation, but much larger tracts are necessary to benefit grassland bird species with high sensitivity to habitat fragmentation (Table 2).
Design grassland plantings for area-sensitive birds to minimize the amount of linear edge. While circular plots are ideal, square plots are preferred to rectangular plots of similar acreage. Avoid establishing restorations with very irregular borders.
Where 50 acre or greater contiguous restorations are not possible, establish several smaller scattered restorations. In this design, individual patches should be at least 15-20 acres in size and preferably be located within a mile of each other. Guidelines for minimizing edge on these patches should be followed. It is highly desirable that any adjacent, grassy habitats such as pastures, hayfields, and grassed waterways be incorporated into the overall design by using them as connections between grassland patches or as non-woody, open edges (Figure 6).

Figure 6 - Preferred placement of grassland wildlife areas in locations where a single, large unit cannot be established. Grassland wildlife plantings are connected to other grassed areas (for example, the hayfield) by a grassed waterway, and are sufficiently far from the homestead and woody hedgerow.
Locate plantings at least 100 yards from forested areas and activity centers such as homes and farmsteads. Immediately adjacent land uses should be structurally open. The planting should not be bordered by tall fencelines or groves of trees because this woody vegetation attracts nest predators and nest parasites.¹⁶ Open pastures, hayfields, small grains, and even row crops are acceptable adjacent habitats.
Use mixtures of tall and short grasses for plantings because some characteristic prairie bird species prefer short vegetation height, whereas others prefer intermediate to tall vegetation height at the start of the breeding season (Figure 7). Native warm season grasses are preferred. Recommended tall grasses for prairie plantings include big bluestem, Indian grass, and switchgrass. Recommended short grasses include little bluestem, side oats grama and prairie dropseed. Monotypic stands are not recommended. The use of short grasses will benefit grassland birds preferring short height grassland areas and may permit renesting by some species after a nest failure.

Figure 7 - Grassland bird species vegetation height and density preferences based on studies in Illinois²⁶ and Missouri.⁵⁴
Include forbs (native flowering herbaceous plants) in the seed mixture or supplement with nursery grown stock, if possible. Most grassland bird species prefer at least low to moderate forb cover (Figure 8). Forbs provide vital habitat components such as song perches and above-ground nesting substrates for many species.⁴⁹

Figure 8 - Grassland bird species forb abundance and low growing, less than 3 feet, woody stem density preferences based on studies in Illinois²⁶ and Missouri.⁵⁴
Conduct prescribed burns on grasslands managed for breeding bird habitat in early spring (March to early April) or late fall (October and November).
Conduct prescribed burns of native or restored prairies over 100 acres in size in a rotation of 20-30% of the area annually since some species of grassland birds prefer recently burned areas whereas others prefer unburned areas.^26,50 On small, isolated grassland areas burn compartments may consist of a larger percentage of the total area, but should not exceed more than 50-60% in any burn season. In areas where several small plantings are in close proximity, management should be directed toward providing both recently burned and unburned habitat by selectively burning parcels on a rotational schedule.⁵¹
Where possible, use existing 'natural' firebreaks as borders of the restoration. Roads, lakes, streams, and frequently mowed areas are good examples of firebreaks. In addition, these edges also may help retard the encroachment of exotic weeds and woody vegetation on to the grassland.
Where existing grassland habitats border forested tracts, allow prescribed fires to burn slowly through the adjacent forest edge into the woods as opposed to installing a firebreak along the forest edge. This management technique will create a more natural open or `feathered' edge between the grassland and forest rather than a sharp, contrasting wall of woody vegetation. Research indicates that sharply contrasting edges have higher nest predation rates than `feathered' edges.⁵²
Remove and control woody vegetation that exceeds the normal grass height. Several Midwestern studies have shown that grassland birds nesting in proximity to woody vegetation suffer significantly higher nest predation and nest parasitism rates than birds nesting far from woody vegetation.^16,53
If hiking trails are to be developed, restrict activities to the edges of the area. Grassland birds are visible and audible from a long distance and supplemental plantings can provide adequate viewing of prairie vegetation.
Grazing, if properly controlled, can be a versatile technique for managing grassland areas for breeding birds.^51,54 Studies in Missouri have shown that light to moderate grazing may benefit several grassland bird species.⁵⁴ Light grazing resulting in approximately 40% or more of vegetation cover at 10 inches in height, would benefit grassland bird species with intermediate vegetation height and density preferences. Moderate grazing resulting in approximately 20 to 40% of vegetation cover at 10 inches in height would benefit grassland species with low vegetation height and density preferences (see Figure 7). The most desirable grazing practice would be to keep grazing pressure light and use a rotation system by which only some sections are grazed and other areas are left idle. For example, an area could be divided into thirds, with the three subunits receiving light, moderate and no grazing regimes on an annual rotational pattern.
Mow parts of grassland areas for hay or weed or woody vegetation control as another grassland management alternative. However, such mowing must be avoided prior to late July or early August because several studies have now documented high rates of fledgling and nest mortality in grassland areas subjected to mid-season cutting.^46,55,56 Avoid cutting prairie areas very late in the growing season because this adversely affects plant species composition and regrowth⁵⁷, and encourages the invasion of problem grass species such as Kentucky bluegrass.⁵⁴ As with burning and grazing, manage mowed grasslands on a rotational system with some subunits left idle in each year.

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