Free-living gerbils with higher testosterone take fewer risks.

Area of Science:

• Behavioral Ecology
• Endocrinology
• Animal Behavior

Background:

• Circulating androgen levels, particularly testosterone (T), differ between sexes and are linked to aggression and risk-taking in male vertebrates.
• The role of T in female behavior is less studied, with assumed higher costs for reproduction and higher benefits for males.

Purpose of the Study:

• To investigate the association between endogenous testosterone levels and risk-taking behaviors in male and female Baluchistan gerbils (Gerbillus nanus).
• To experimentally determine the effects of elevated testosterone on risk-taking behavior in this species.

Main Methods:

• Assessed the relationship between endogenous T levels and risk-taking in free-living gerbils under experimental conditions.
• Experimentally increased T levels in gerbils using implants and measured subsequent risk-taking behavior.
• Observed foraging behavior in both risky and safe patches and activity patterns during different lunar phases.

Main Results:

• Found no sex differences in the association between T and risk-taking; higher T levels were surprisingly linked to fewer risks in both sexes.
• Gerbils spent equal time foraging in risky and safe patches, indicating a balanced approach to resource acquisition.
• Contrary to expectations for nocturnal animals, gerbils were more active during moonlit nights than dark nights.

Conclusions:

• Testosterone's effects on behavior are complex and species-specific, challenging universal hypotheses about its role in risk-taking.
• Environmental factors like light regimes and predator presence significantly influence risk-taking strategies, which are not solely dictated by hormone levels.
• This study highlights the need to consider species, environment, and context when interpreting the behavioral functions of hormones.