Spanning approximately 40 miles in length, the Jackson-Washington/Clark State Forest Important Bird Area comprises one of the largest remaining forest tracts in Indiana. Located mostly along the Knobstone Escarpment in Jackson, Washington, Scott and Clark Counties in southern Indiana, much of the habitat within the IBA is late successional and mature forest, making this a critical locale for breeding forest interior birds.
As its name suggests, two state-owned properties constitute the majority of land within this Important Bird Area ? Jackson-Washington State Forest (approximately 17,000 acres) and Clark State Forest (approximately 25,000 acres) ? although some privately-held lands are included within the boundary to assure continuity.
The Jackson-Washington and Clark State Forests likely comprise one of the largest and most diverse breeding communities of forest-dependent birds in Indiana. A plethora of WatchList species can be found here during the summertime, including such declining neotropical birds as Wood Thrush, Cerulean Warbler, Worm-eating Warbler, and Kentucky Warbler. The abundance of steep-sided slopes and ravines found at the two state forests seem particularly attractive to the Worm-eating Warbler ? its nesting population at these two locales combined possibly total more than 1000 individuals.
Several forest birds listed as ?special concern? by Indiana?s Department of Natural Resources can be found at this IBA, too. Hooded Warbler is one of the most common of all the breeding birds within Jackson-Washington and Clark State Forests, and Black-and-White Warbler, a rare breeder throughout the state, is present here during the nesting season.
Early reforestation practices at the state-owned properties and Virginia pine stands native to the region have created woodlots that support species that are relatively uncommon throughout the remainder of the state. Black-throated Green Warblers, which are almost completely absent from Indiana during the summer, and Pine Warblers are regularly found in such mixed and pine forests. These stands also support greater populations of Yellow-throated Warblers relative to many deciduous forest tracts; Partners In Flight considers this bird a ?Regional Stewardship? species for the area, so it?s abundance in these tracts is quite significant for conservation.
Since some timber harvest does occur in these two state forests, some early successional areas are available for birds with this habitat preference. For instance, Ruffed Grouse, which has declined precipitously throughout the state in the last 40 years, still can be found drumming in such openings during the spring.
Perhaps the most significant threat to the forest-interior bird communities of the Highland Rim Natural Region is a recently proposed increase of timber cutting within state-owned forests. Historically, the state has opened up for harvest about 3.4 million board-feet of forest each year. Under the directive of Indiana's governor, that figure would rise between 10 million and 17 million board-feet. Both the Jackson-Washington and Clark State Forests could be the recipients of such a precipitously increased cutting regime.
Although the proposed harvesting would create more early to mid-successional habitat within the confines of the state forest, thereby benefiting such species as Prairie Warbler, Yellow-breasted Chat, and Field Sparrow, the loss of mature forest would equally serve as a detriment to bird communities associated with older growth habitats. Consequently, the populations of WatchList species such as Wood Thrush, Worm-eating Warbler, and Kentucky Warbler would most likely be impacted.
In addition, research performed by scientists from Indiana University-Bloomington has illustrated that fragmentation and the creation of forest edges are often associated with higher predation and parasitism levels in nesting neotropical birds within this natural region. These effects, compounded with the loss of mature forest habitat, would certainly cause long-term problems for the reproductive success and population recruitment of forest-interior birds at this Important Bird Area.