Testosterone, paternal behavior, and aggression in the monogamous California mouse (Peromyscus californicus)

Brian C. Trainor, Catherine A. Marler

Research output: Contribution to journalArticlepeer-review

185 Scopus citations


Testosterone (T) mediates a trade-off, or negative correlation, between paternal behavior and aggression in several seasonally breeding avian species. However, the presence or absence of a T-mediated trade-off in mammals has received less attention. We examined the relationship between paternal behavior and territorial aggression in the biparental California mouse, Peromyscus californicus. In contrast to seasonally breeding birds, T maintains paternal behavior in this year-round territorial species. Castration reduced paternal behavior, whereas T replacement maintained high levels of paternal behavior. We hypothesize that T is aromatized in the brain to estradiol, which in turn stimulates paternal behavior. In contrast to paternal behavior, aggressive behavior was not reduced by castration. Interestingly, only sham males showed an increase in aggression across three aggression tests, while no change was detected in castrated or T-replacement males. Overall, trade-offs between aggression and paternal behavior do not appear to occur in this species. Measures of paternal behavior and aggression in a correlational experiment were actually positively correlated. Our data suggest that it may be worth reexamining the role that T plays in regulating mammalian paternal behavior.

Original languageEnglish (US)
Pages (from-to)32-42
Number of pages11
JournalHormones and Behavior
Issue number1
StatePublished - 2001
Externally publishedYes


  • Aggression
  • Paternal behavior
  • Peromyscus californicus
  • Testosterone
  • Trade-offs

ASJC Scopus subject areas

  • Endocrinology
  • Behavioral Neuroscience
  • Neurology
  • Psychology(all)


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