Donald H. White,¹ Christine A. Mitchell,¹ Elizabeth J. Kolbe,² William H. Ferguson<sup>3

1</sup>U.S. Fish and Wildlife Service, Patuxent Wildlife Research Center, Gulf Coast Field Station, P.O. Box 2506, Victoria, Texas 77902, USA
²U.S. Fish and Wildlife Service, Patuxent Wildlife Research Center, Laurel, Maryland 20708, USA
³U.S. Fish and Wildlife Service, Post Office and Courts Bldg., Lake Charles, Louisiana 70601, USA