A quantitative method for sex identification in emydid turtles using secondary sexual characters

Anne M. Readel, Michael Joseph Dreslik, Jonathan K. Warner, Whitney J. Banning, Christopher A Phillips

Research output: Contribution to journalArticle


Accurate classification of sex is essential for life history studies. Benchmark sizes that can represent the size of either the smallest, average, or upper size limit of males in a population exhibiting secondary sexual characters (SSCs) are often used to assign sex in emydid turtles. This method may be problematic, however, as it ignores variation in SSC development and is unable to identify the sex of smaller individuals. To address these two issues, we present a method using Slider Turtle (Trachemys scripta) standardized residual scores of third foreclaw length and preanal tail length versus plastron length. The use of benchmark sizes that reflected the smallest or average size of male maturity for our population did not compromise accurate sex identification. Additionally, our method was able to accurately sex turtles that were smaller than the benchmark size. Our method has the potential to enhance demographic studies on turtles by allowing researchers to identify juvenile sex ratios.

Original languageEnglish (US)
Pages (from-to)643-647
Number of pages5
Issue number3
StatePublished - Sep 10 2008


ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Aquatic Science
  • Animal Science and Zoology

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