Recent studies have suggested that measuring animal behaviour in captivity may not be attributed to natural settings and there is a need for candidate traits that can be measured in the wild. In this respect, anti-predator behaviours vary consistently between individuals and can be easily measured during the breeding time. In response to nest predation, many bird species produce specific sounds, such as hissing calls in incubating great tit (Parus major). Hissing behaviour has been shown to be repeatable, yet variable between individuals, indicating that anti-predator behaviour in female great tits may be related to personality. We predicted that hissing behaviour conveys information on individual-specific behavioural aspects, such as risk-taking, and aggressiveness, as well as behavioural decisions related to reproductive investment. Our three-year study on free-living great tits revealed that fast-responding birds bred in less populated areas, suggesting that hissing behaviour can be connected to sociality. Further, we established that fast-responding females started to lay eggs earlier in the season. This finding may demonstrate that hissing rate can be related to differences in female or habitat quality. However, hissing behaviour was not correlated to clutch size, indicating no relation to reproductive investment. We suggest that female great tit’s hissing behaviour may be a potentially suitable candidate trait for measuring personality in the wild. We also propose that hissing behaviour as a certain form of nest defence may reflect individual aggressiveness. In conclusion, we encourage studying naturally occurring between-individually variable anti-predator behaviours in free-living animal species.