The giant panda, Tasmanian tiger, and hundreds of other endangered species are living on the fringes of their historical habitats rather than in their centers, according to a study published yesterday in the journal Nature. Researchers from the University of Oklahoma and Fort Hayes State University in Kansas studied the geographical ranges of 245 endangered or recently extinct species and found that most of them had been driven by human interference to the edges of their historical habitat, areas more fraught with risk than the centers. The study could have major implications for conservation strategy because efforts to protect endangered species tend to concentrate on the centers of habitat areas.