BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 38 PT. 1(4)


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 220 230 240 250 260 270 280 290 300

 CARAPACE LENGTH (mm)


Figure 12. Relationship between clutch size and carapace length of 24 gopher tortoises on the Katharine
Ordway Preserve, Putnam Co., Florida. The regression equation is: Clutch size = -2.198 + 0.0312(Carapace
length).



 Clutch size.- Mean clutch size for the three year period was 5.76 (n = 51,
SD = 1.57) (Table 7) which is comparable to literature records of 5.2-5.8 for
northern Florida (Hallinan 1923; Iverson 1980; Taylor 1982b; Diemer 1986).
Mean clutch size in 1990, at the height of the five-year drought, was less than in
1991 when seasonal rainfall was near average (t = -1.684, df = 39, 0.025 < p <
0.05). Some of the variation between years might be explained by a difference in
female size. Mean carapace length of gravid females for the two years was not
significantly different (t = 0.659, df = 21, p > 0.10), although the size of females
that deposited their eggs at aprons is not known. The relationship between drought
and reproduction in the gopher tortoise has not been documented. However, a
drought-related decrease in clutch frequency has been reported in the desert
tortoise (G. agassizii) and in some species of aquatic turtles (Gibbons et al. 1983;
Turner et al. 1984). A decrease in the number of individuals that produce eggs
during drought also has been documented in four species of aquatic turtles
(Gibbons et al. 1983).