THE ECOLOGY OF A SANDHILLS POPULATION
 OF THE EASTERN NARROW-MOUTHED TOAD,
 GASTROPHRYNE CAROLINENSIS,
 DURING A DROUGHT



 C. Kenneth Dodd, Jr.'




 ABSTRACT


 The eastern narrow-mouthed toad, Gastrophryne carolinensis, is a common inhabitant of sandhill
uplands in north-central Florida. From 1986 through 1990, I monitored a population of this species at a
0.16 ha wetland on the Katharine Ordway Preserve-Swisher Memorial Sanctuary, Putnam County, Florida.
The pond held water only 14 mo during the 60-mo study. A drift fence-pitfall trap system encircled the pond
basin to capture eastern narrow-mouthed toads as they entered and exited. A total of 5740 eastern narrow-
mouthed toads (including recaptures) were captured despite a severe drought during the latter years of the
study. In 1986 and 1988, approximately 900 eastern narrow-mouthed toads entered the pond, but the
numbers fluctuated substantially in the other years. Few multi-year recaptures were recorded, although two
eastern narrow-mouthed toads were captured four years after initial marking. Although eastern narrow-
mouthed toads were active during all months of the year, peak activity occurred from June through
September. Reproduction was successful only during the summer of 1985, and juveniles exited the pond
basin through the spring of 1986. The adult population size-class structure remained consistent throughout
the study, although the population size decreased. The adult sex ratio was male-biased in all years except
1990. Males were smaller than females in both snout-urostyle length (SUL) and weight, and differences
were significant among years and between sexes. Drought eliminated reproduction for five years and seemed
to reduce overall population size, but direct correlations between drought effects and natural stochastic
variation are not yet possible. My data suggest that G. carolinensis survives long-term droughts by
maintaining large populations scattered across a variety of habitats and because at least some individuals are
opportunistic, rather than philopatric, in their choice of breeding sites. Long-term studies and manipulative
field experiments will assist in answering some of the many questions raised by these results.





SThe author is a Research Zoologist, National Biological Service, Biological Science Center, 7920 NW 71st Street, Gainesville FL 32653,
U.S.A., and Curator (Courtesy) of the Florida Museum of Natural History, and an Associate Professor (Courtesy) with the Department of
Wildlife Ecology and Conservation, University of Florida.

DODD, C.K., JR. 1995. The ecology of a sandhills population of the eastern narrow-mouthed toad,
Gastrophryne carolinensis, during a drought. Bull. Florida Mus. Nat Hist., Biol. Sci. 38, Pt I(1):11-41.