The leading rooster within a group always crows first to announce the break of dawn according to research published in Scientific Reports this week. The rest of the roosters will then crow in order of descending social rank.

Chickens are highly social animals and crowing is thought to be a means of warning others of the boundaries of their territory, thus avoiding the risk of aggressive interactions. In groups, chickens can develop a hierarchy in which higher-ranking roosters have priority for food, mating rights and resources such as nests and roosting places.

Tsuyoshi Shimmura, Takashi Yoshimura and their colleague investigated if the social hierarchy among roosters has an effect on crowing at the break of dawn. The authors found that in a group of four roosters, the highest ranking rooster would crow first every morning, followed by its subordinates in descending order of their social rank. They also observed that lower-ranking roosters crowed less often than the high-ranking roosters. When the top-ranking rooster was removed from the experiment, the second-ranking rooster became the first to crow, suggesting that predawn crowing by subordinate roosters is suppressed by the presence of the dominant rooster.