Paul Douglas Forest Preserve is bounded by Algonquin Road, Central Road, Ela Road and Freeman Road, forming a contiguous natural area of 1,382 acres in northeastern Illinois, southwest of the town of Palatine. The natural area to the east of Ela Road adds another 565 acres for a total of 1,947 acres. The preserve consists of large areas of both grassland and degraded oak savanna interspersed with plantations of maple, elm and other trees.
Poplar Creek bisects the preserve, and large wetlands exist on both sides of the banks, as well as several forested and partially forested wetlands.
Paul Douglas Preserve has extensive grassland fields some of them containing mixes of old-field species such as timothy, Hungarian brome, goldenrod, milkweed and bluegrass, but the structure mimics that of the ecosystem that prairie birds called home until European settlement.
Paul Douglas contains extensive grassland areas that support unusually high numbers of breeding Bobolink and Henslow's Sparrow. A large marsh on the site also contains a diverse mix of breeding birds including Yellow-headed Blackbird, Pied-billed Grebe, swallows, ducks, rails and other waterfowl.
This site was chosen as an IBA because it met the criteria for breeding Yellow-headed Blackbird and Henslow's Sparrow.
The major wetland area was completely dry during most of the summer of 2005, possibly as a result of work being done under I-90 to remove the boards from the Central Road dam. The dam was built three or four years ago so each summer the wetland would dry out. Only after the dam was established did the Yellow-headed Blackbirds and other wetland species breed and spend the summer.
Extensive mowed soccer fields encroach on surrounding grasslands that are important for breeding birds. Dog walkers occasionally disturb nesting birds, especially closer to the parking lot and marsh.
Paul Douglas Preserve contains grasslands, wetlands, degraded oak savanna and some old-fields.