More than 20 endangered species of wildlife have been found in Virginia, Maryland and the District of Columbia, ranging from the much-studied sea turtle to the renowned bald eagle and the little-known Maryland darter.

Even within the District, one rare animal faces possible extinction. It is the Hay's Spring amphipod, a tiny aquatic crustacean found only in a small spring on the grounds of the National Zoo. Officials have sought to conceal its whereabouts to avoid possible vandalism.

The bald eagle, the nation's white-headed symbol, is reported by scientists to be recovering after years of decline caused by pesticides and other factors. Its revival has been closely watched in Maryland and Virginia, where scientists are also seeking to protect the peregrine falcon, another endangered bird of prey.

The Maryland darter, an imperiled species of freshwater perch, has been discovered only in two streams in Harford County in the northeastern part of the state. Another endangered fish -- the snail darter, not found in Maryland -- gained fame in the 1970s when it delayed construction of the $120 million Tellico Dam in Tennessee.

Also protected under the Endangered Species Act is the Delmarva fox squirrel, a large grayish creature found on the Eastern Shore of Maryland and Virginia. The endangered red-cockaded woodpecker, a small black, white and red bird, is also found in both states.

One imperiled tree, the Virginia round-leaf birch, grows only in Smyth County in the state's southwestern corner. Also found in southwestern Virginia are nine endangered species of freshwater mussels and two other threatened species of fish, the yellowfin madtom, which resembles a catfish, and the tiny spotfin chub. One other endangered fish, the shortnose sturgeon, is found off Virginia's eastern coast and in the Chesapeake Bay.

The endangered Indiana bat, a brown and pinkish-white animal, has been sighted in western parts of Maryland and Virginia.