1. North Carolina Cooperative Fish and Wildlife Research Unit, Department of Applied Ecology; North Carolina State University; Raleigh NC 27695 U.S.A.
2. U.S. Geological Survey, North Carolina Cooperative Fish and Wildlife Research Unit, Department of Applied Ecology; North Carolina State University; Raleigh NC 27695 U.S.A.
3. Department of Forestry and Environmental Resources; North Carolina State University; Raleigh NC 7695 U.S.A.
4. Department of Statistics; North Carolina State University; Raleigh NC 27695 U.S.A.