Fifty-year trends in a box turtle population in Maryland

A survey conducted in 1995 investigated long term declines reported in a po pulation of box turtles Terrapene carolina monitored each decade since 1945 in bottomland hardwood forest at the Patuxent Wildlife Research Center, Ma ryland. Methods duplicated past surveys in most respects, but were suppleme nted by radiotelemetry and a survey of dominant vegetation. Seventy differe nt turtles were found on the 11.8 ha study area, a decline of > 75% since p eak populations were recorded in 1955. Searchers were less efficient in 199 5 than in 1945-1975 for a variety of possible reasons. Among turtles record ed, approximately equal numbers persisted from each of the past five decade s, with some individuals surviving > 70 years. A sex ratio strongly favorin g males was first recorded in 1975 and continued in 1995, but juveniles and subadults were found in greater proportion in 1995 than in any other surve y. Six of nine radio-marked turtles left the bottomland study area and migr ated to the adjoining bluffs to hibernate, suggesting more extensive moveme nts and perhaps less stable home ranges than formerly thought. Age structur e of trees indicated a gradual change to more shade-tolerant species. Exami nation of rates of change from survey data suggested that major losses prob ably resulted from changes in hydrology that exacerbated flooding in 1972, with recovery only beginning in 1995 and perhaps limited both by repeated f lood events and successional changes in the forest. Slow recovery from loss es may indicate that populations of this species would respond poorly to ex ploitation. (C) 1999 Elsevier Science Ltd. All rights reserved.