DODD: ECOLOGY OF SANDHILLS POPULATION OF GASTROPHRYNE CAROLINENSIS 37


 Although many amphibians show site fidelity to a particular breeding pond
(Martof 1953; Shoop 1965; Gill 1978, 1985; Semlitsch 1981; Duellman and Trueb
1986; Smith 1987), this had not been demonstrated previously for G. carolinensis.
Anderson (1954) reported that a population of eastern narrow-mouthed toads in
Louisiana attempted to breed at the site of a pond bulldozed the previous year. In
the present study, multi-year recaptures suggest some degree of site fidelity in
breeding site choice. If site fidelity is strong, interdemic migration probably is not
significant. Even if most of the population never moves to another breeding site,
however, a few toads might do so. Only a few wandering reproductive toads could
recolonize a new or former breeding site.

 Refugia.-Gastrophryne carolinensis could stay in terrestrial refugia until
drought conditions end, if they can live long enough to outlast the drought. The
two toads captured four years after initial marking are the longest lived individuals
reported from a free-ranging population of this species. Fitch (1956) also captured
several G. olivacea known to be in their fourth year and speculated that some
individuals can live a few more years. Droughts that result in the loss of breeding
sites more than four years in a row might begin seriously to deplete a local
population. If this is the case, the study at Breezeway Pond ended at a critical
juncture.


 CONCLUSIONS


 To understand how an amphibian population is affected by drought, it is
necessary to recognize that the frogs that visit a pond represent a fraction of the
total population (Crump 1982). The population of eastern narrow-mouthed toads
that inhabits the Breezeway Pond region includes juveniles, non-reproductive
adults, and breeding adults. The reproductive population of G. carolinensis
probably contains a large number of individuals dispersed at substantial distances
from a breeding site. The population is widely distributed, with toads dispersing
evenly toward the various environments surrounding the pond (sandhills, xeric
hammock, meadow) (Dodd unpubl.). Eastern narrow-mouthed toads have been
seen in sandhills more than 500 m from the nearest potential breeding location
(pers. obs.).
 Amphibians living in unpredictable environments should be flexible in life
 history traits (Wilbur 1972; Crump 1982). Unlike the sympatric striped newt
 (Dodd 1993), I suggest that the eastern narrow-mouthed toad probably does not
 survive a drought through a combination of long life span and opportunistic timing
 of reproduction. Subterranean habits, the abundance of ants and termites for food,
 a short larval period, and the ability to use a wide variety of temporary wetlands for
 breeding probably allows G. carolinensis to colonize the otherwise harsh sandhills