Winner effects and switching assessment strategies facilitate fast and frugal decisions in territorial contests

Animals compete in contests over limited resources, and contestants with greater fighting ability, or resource holding potential (RHP), typically win contests. Contest strategies have evolved to balance contest costs with the benefit of winning resources. Sometimes, contestants decide to leave by estimating their opponent’s relative RHP . This strategy (mutual assessment) is cost-effective because it allows weaker opponents to leave contests against formidable opponents before accruing higher costs. However, acquiring reliable information can be costly. Here, we showed that in snapping shrimp contests, contestants assessed relative RHP quickly and costeffectively by assessing their opponent’s recent contest success. By staging 26 contests between randomly matched individuals and 24 contests between RHPmatched individuals, we determined that snapping shrimp assessed their opponent’s RHP during initial contest phases but no longer assessed relative RHP during escalated phases. Then, after...