The ability to combine words to create sentences (syntactic) is said to have evolved uniquely to humans, and in fact, no such syntactic ability has been found in primates such as chimpanzees.Past research by the research team has shown that great tit uses different types of barks depending on the situation.This research examines what kind of information the great tit conveys by the combination of barks.

　Great tit conveys the meaning of "gather" with a high-pitched cry of "Petsupi" and a muddy voice of "Beware".Through experiments, we have confirmed that when these sounds are recorded and played back from the speaker, they actually take alert actions and actions that approach the sound source.Next, when I played "Petsupi Jijijiji", which was a combination of the two voices, I approached the sound source while being cautious of the surroundings.However, when I changed the order to "Jijiji Peatsupi" and played it, no reaction was seen.From this, it was found that the combination of sounds was used to combine meanings, and that information was conveyed according to specific grammatical rules.This achievement is a breakthrough that overturns the scientific speculation since Darwin that syntactic ability is peculiar to humans.

　Great tit has been found to produce more than 10 unique calls by combining more than 175 different phonetic elements, such as noun-like calls that indicate the existence of "snakes" and "hawks."In the future, we plan to clarify the content of information transmission by voice elements other than "Petsupi" and "Jijijiji", and to consider similar abilities in other birds.