The coping style of an individual in relation to potentially dangerous situations has been suggested to be inherited in a polygenic fashion, SERT being one of the candidate genes. In this study, we assessed in free-living great tits (Parus major) the association between SNP290 in the SERT promoter and three standard fear-related behaviors: the response of the birds to a black-and-white flag fixed to the top of the nest box, distress calling rate of the birds in the hand once captured and the hissing call of incubating females when approached by a predator. We found a strong association between SNP290 polymorphism and the three risk-taking behaviors, with birds with genotype CT entering the nest box with the flag faster and displaying more distress calls and fewer hissing calls. CT birds could therefore be described as more proactive than CC individuals. These results also suggest that hissing behavior should be regarded as a fear-induced shy behavior, and confirm that SERT has an important function in relation to risk aversion behaviors and coping style.