SREL Reprint #0200

 

 

 

Ecology and Population Dynamics of the Chicken Turtle, Deirochelys reticularia

J. Whitfield Gibbons

 

Abstract

Studies 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.

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