Variation in Reproductive Characteristics of Aquatic Turtles

Abstract

little effect on the correlation between body size and clutch size. A linear model of the relationship between body size (plastron length) and clutch size explained 67% of the variation for Pseudemys floridana, 56% for P. scripta and 25% for Sternotherus odoratus. A linear model was not useful in describing the pattern in the other two species (r2 = .05, Kinosternon subrubrum and .08, Deirochelys reticularia). However, within each of the five species, maximum clutch sizes of the smallest individuals are never as large as the maximum clutch sizes of the largest individuals. Clutch sizes within a species did not vary significantly among years or populations if the effect of body size was removed. Clutch size varied among months in all species, with a trend of decreasing clutch size during the egg-laying season apparent for P. scripta, P. floridana and K. subrubrum. Individuals of four species were recorded laying more than one clutch within a single egg laying season. The proportion of adult females known to have multiple clutches within a year varied for each species. Monthly timing of egg laying was not consistent for an individual female from year to year. No relationship could be identified between clutch frequency and body size in K. subrubrum or P. scripta, the only species for which adequate samples were available for such an analysis.