Post-drought responses of semi-aquatic snakes inhabiting an isolated wetland: Insights on different strategies for persistence in a dynamic habitat
John D. Willson1, Christopher T. Winne1, Michael E. Dorcas2, J Whitfield Gibbons1
1
Savannah River Ecology Laboratory
PO Drawer E
Aiken, South Carolina, USA 29802
willson@srel.edu
2
Department of Biology
Davidson College
Davidson, North Carolina, USA 28035
Abstract
Most aquatic habitats are temporally dynamic, and selection has favored
diverse strategies to persist in the face of fluctuating environmental
conditions. Isolated wetlands in the southeastern United States harbor
high diversities of aquatic and semi-aquatic organisms. However, drought
may render these wetlands temporarily unsuitable for many species, sometimes
for years at a time. We studied the movement patterns and demography of
seven species of semi-aquatic snakes at Ellenton Bay, an isolated 10-ha
freshwater wetland in the Upper Coastal Plain of South Carolina, following
complete drying of the bay during a drought from 2000 to 2003. Behavioral
and population responses varied markedly among species. Cottonmouths (Agkistrodon
piscivorus) migrated to and from the wetland annually, fared well,
and reproduced during the drought. Banded watersnakes (Nerodia fasciata)
suffered a dramatic population decline and apparently did not reproduce,
while eastern green watersnakes (N. floridana) were locally extirpated.
Black swamp snakes (Seminatrix pygaea) aestivated within the wetland
and were less affected by the drought than Nerodia. Interspecific
differences in response to drought demonstrate that conservation measures
may affect species differently and highlight the importance of terrestrial
habitat around wetlands for semi-aquatic reptiles.
Keywords:
Agkistrodon piscivorus, drought, Farancia abacura, Farancia
erytrogramma, metapopulation dynamics, Nerodia erythrogaster, Nerodia
fasciata, Nerodia floridana, Seminatrix pygaea, wetland conservation
SREL Reprint #3008
Willson, J. D., C. T. Winne, M. E. Dorcas and J. W. Gibbons. 2006. Post-drought responses of semi-aquatic snakes inhabiting an isolated wetland: Insights on different strategies for persistence in a dynamic habitat. Wetlands 26:1071-1078.
