Biological conclusions about importance of order in mobbing calls vary with the reproductive context in Great Tits ( Parus major )

International audienceCurrently, there is considerable debate surrounding the presence of some human language-specific characteristics in non-human animals, such as the use of compositional syntax (i.e. meaning of a sequence determined both by meaning of its individual parts and in the way they are combined). Compositional syntax has been investigated in mobbing calls of two closely related tit species, the Japanese Tit Parus minor and the Great Tit Parus major, but with one contrasting result: hearing calls in the reversed order diminished the behavioural responses of Japanese Tits but only partially those of Great Tits. This difference may have been due to an external factor such as the season in which the experiment was undertaken, as the Japanese Tits were tested in winter and Great Tits in spring. Here, we studied the responses of Great Tits towards natural and reversed mobbing sequences during spring and winter by investigating two behaviours: approaching and vigilance behaviours. We found that sensitivity to syntax reversal was impacted by the season. The birds were vigilant but less likely to approach reversed calls in winter. However, the opposite occurred in spring, with the birds scanning less but still approaching. This study suggests that the perception of combinatorial calls in Great Tits is influenced by the season, emphasizing the importance of context in studies investigating complex cognitive processing in animals