BULLETIN FLORIDA MUSEUM NATURAL HISTORY 38(1)


activity solely from external characters is impossible. I marked frogs by clipping
toes using a year-specific cohort sequence; no more than one toe was clipped per
foot. I carefully examined all captured animals for regenerated toes. Frogs were
released on the opposite side of the fence from where they were captured.
 In addition to biological data, I recorded maximum and minimum air and
water temperature and rainfall since the pitfalls were last checked, current weather
conditions, and the occurrence of cyclic weather patterns (e.g. cold fronts, severe
storms, etc.).
 Eastern narrow-mouthed toads marked in one year and recaptured in another
year presented special data analysis problems, because I could not determine
whether an individual had been caught more than once during the second year.
Either combining or excluding counts of previously marked frogs with first-caught
frogs will give an imprecise picture of population structure and sex ratio of the
breeding population. In the results and discussion below, I arbitrarily chose to
exclude multi-year recaptures; descriptive statistics relate to previously unmarked
animals caught within a year cohort. Multi-year recaptures are treated separately
in the paper.


 RESULTS
 Hydroperiod and Rainfall


 From 1985 to 1990, generally small amounts of rain falling in the vicinity of
Breezeway Pond resulted in short hydroperiods at various times of the year (Dodd
1992). Large lakes also dried as the water table dropped > 2.5 m throughout
north-central and northeastern Florida from 1988 to 1990. Although the
maximum recorded water depth at Breezeway Pond was 75 cm, the pond held
water for only 14 mo from January 1985 through September 1990 (Fig. 1). The
water table was located 60 cm below the ground surface of the bottom of the pond
in October 1989 (LaClaire and Smith unpubl.). By February 1991, the water table
had dropped to 2.5 m below the ground surface and the central pond area was
colonized by a thick growth of Panicum.
 The driest months at Breezeway Pond were April and October, whereas the
wettest months generally were in the summer, except in 1987 and 1988 (Fig. 1).
Less than 300 mm of rain fell in any one month except in September 1988, when a
tropical depression brought 270 mm of rain in four days. Rainfall was sporadic,
however, and very dry months occurred at all times of the year, especially from
October 1988 through September 1990.
 In the summer (mid-May through mid-September), thunderstorms provided
 most of the rainfall in the vicinity of Breezeway Pond. However, rainfall from
 thunderstorms was localized and, during the latter years of the study, was