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Understanding testosterone variation in a tropical lek-breeding bird
Thomas B Ryder1, Brent M Horton, Ignacio T Moore
1Migratory Bird Center, Smithsonian Conservation Biology Institute, National Zoological Park, PO Box 37012-MRC5503, Washington, DC 20008, USA. rydert@si.edu
Biology Letters
|February 18, 2011
Summary
Male wire-tailed manakins form cooperative display coalitions. Testosterone levels predict social status, with territorial males showing higher levels, suggesting a role in both competition and cooperation.
Area of Science:
- Behavioral Ecology
- Endocrinology
- Evolutionary Biology
Background:
- Male reproductive coalitions are rare in vertebrates.
- Hormonal mechanisms modulating cooperative behaviors are poorly understood.
Purpose of the Study:
- To investigate the role of testosterone in modulating cooperative behaviors in male wire-tailed manakins (Pipra filicauda).
- To examine the relationship between testosterone levels, social status, and cooperative display coalitions in a tropical lekking bird.
Main Methods:
- Measured testosterone levels in male wire-tailed manakins across different social statuses (territorial vs. floater males).
- Correlated testosterone levels with social status and plumage characteristics.
Main Results:
- Testosterone levels in territorial males were comparable to temperate birds.
- Social status, not plumage, strongly predicted testosterone variation.
- Territorial males exhibited significantly higher testosterone levels than floater males.
Conclusions:
- Testosterone variation is crucial for establishing male dominance hierarchies and competition.
- Testosterone likely facilitates stable cooperative display partnerships in male manakins.
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