(PhysOrg.com) -- The Carrizo Plain National Monument in south-central California is the largest single native grassland remaining in the state. One of its denizens is a small creature known as the giant kangaroo rat, which has spent decades on both the federal and state endangered species lists while eking out a living on less than 2 percent of its original range. Isolated areas in Central California west of the San Joaquin Valley, like the Carrizo Plain, are all it has left.