The Nature Conservancy's Cucumber Creek Nature Preserve was created in 1989 to benefit neotropical migrant birds. These birds nest in the summer in large blocks of continuous forest in North America and migrate long distances to Central and South America to spend the winter. Thirty-three species of birds, more than half of them neotropical migrants, nest on the preserve. In addition, many plants and animals found only in the Ouachita Mountains are protected at the Cucumber Creek Nature Preserve.

The preserve encompasses 3,270 acres and is located in LeFlore County, near the Arkansas border. Cucumber Creek is a clear, high-gradient stream flanked to the north by Kiamichi Mountain and to the south by Blue Bouncer Mountain. Lynn Mountain divides Cucumber Creek from the Beech Creek National Scenic Recreation Area, part of the Ouachita National Forest.

The creek is named for the Cucumber magnolia, a small tree native to Eastern forests whose range barely extends into Oklahoma in the Ouachitas.

The Cucumber Creek Nature Preserve is rugged and remote. There are no facilities. Old logging roads leading to the creek are in very poor condition and generally impassable by vehicle. The Conservancy recommends that visitors use similar, nearby areas of the National Forest for recreation. The Beech Creek National Scenic Recreation Area has a parking area and trail system.

Though birds are the focus of this preserve, the biodiversity of the region is impressive. Other animal species include black bears, zebra swallowtails, white-tailed deer, timber rattlesnakes, and cottonmouths. There are at least 39 preserve plants and animals that are found only in the Ouachitas, including the Ouachita Mountain Shiner, a small fish at home in Cucumber Creek.