Transient Masculinization in the Fossa, Cryptoprocta ferox (Carnivora, Viverridae)

C. E. Hawkins, John F Dallas, Paul Alfred Francois Fowler, R. Woodroffe, Paul Adrian Racey

Research output: Contribution to journalArticlepeer-review

31 Citations (Scopus)


In at least 9 mammalian species, females are masculinized throughout life, but the benefits of this remain unclear despite decades of thorough study, in particular of the spotted hyaena (Crocuta crocuta) in which the phenomenon has been associated with a high fitness cost. Through examination of wild and captive fossas (Cryptoprocta ferox, Viverridae), androgen assays' and DNA typing for confirmation of gender, we made the first discovery of transient masculinization of a female mammal. juvenile female fossas exhibited an enlarged, spinescent clitoris supported by an os clitoridis and a pigmented secretion on the underpart fur that in adults was confined to males. These features appeared to diminish with age. The majority of adult females lacked them, and os clitoridis length was inversely related to head-body length. No evidence was found to link this masculinization to elevated female androgen levels. Circulating concentrations of testosterone and androstenedione, but not dihydrotestosterone, were significantly lower in females than in males. No significant differences in testosterone, androstenedione, or dihydrotestosterone levels were found between juvenile (masculinized) and adult (nonmasculinized) females. There are several possible physiological mechanisms for this masculinization. None of the hypotheses so far proposed to explain the evolutionary basis of female masculinization in mammals are applicable to our findings. We present 2 new hypotheses for testing and development.

Original languageEnglish
Pages (from-to)610-615
Number of pages5
JournalBiology of Reproduction
Issue number3
Publication statusPublished - 1 Mar 2002


  • behavior
  • female reproductive tract
  • male reproductive tract
  • penis
  • puberty
  • steroid hormones
  • testosterone
  • hyaenas crocuta-crocuta
  • spotted hyenas
  • females
  • mole


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