|SREL Reprint #0200|
and Population Dynamics of the Chicken Turtle, Deirochelys reticularia
J. Whitfield Gibbons
involving the population dynamics and ecology of Deirochelys reticularia
were investigated by a mark-release-recapture program in and around an aquatic
area near Aiken, South Carolina. Reproductive
attributes of the species were determined by dissecting preserved specimens.
Growth rates of individuals from the study
population were 25-20 mm/year up to a plastron length of 90-100 mm for males and
130-150 mm for females. Growth rate
apparently slows drastically when maturity is reached.
Males have a higher ratio of preanal length to plastron length and
females reach a larger maximum size. The
sex ratio of 74 individuals collected was 1 male: 0.54 female but this is
attributable to sampling bias and probably does not represent the true sex
ratio. Males reach maturity between
75 and 85 mm in plastron length, presumably during their second or third growing
season. Seasonal testicular changes
appear to be similar to other emydid turtles, with the testes being largest in
early summer and smallest in the spring. Females
greater than 160 mm in plastron length are mature, those 145-160 mm are just
attaining maturity. Females greater
than 180 mm apparently become reproductively senile or have biennial or
triennial reproductive cycles. Smaller
mature females, however, may lay two clutches per year.
Clutch size is usually five to seven eggs; and laying begins as early as
March. Three phases of terrestrial
activity are apparent: a period of
gravid adult female activity in early spring; a period in April when males and
females are active on land; a period late spring which consists predominately of
adult males. Some
hatchlings overwinter in the nest whereas others do not.
SREL Reprint #0200
Gibbons, J.W. 1969. Ecology and population dynamics
of the chicken turtle, Deirochelys reticularia. Copeia 1969:669-676.