Do songbirds socialise during migration?

The flight paths of migrating songbirds may not be entirely innate, a new study has found. Evidence from over 18,300 hours of recorded flight calls suggests songbirds may “talk” to other species as they migrate, forming social connections and — just maybe — exchanging information about the journey. Another study suggested that birds “buddy up” with other species at stopover sites during migration, but there was no evidence to show that different songbird species pair up or communicate vocally on the wing. Using a machine learning tool allowed researchers to analyse 18,300 hours of acoustic record to quickly detect the signature flight calls of 27 species, including 25 well-sampled songbirds. After identifying species, the team measured how often certain calls co-occurred in time, testing intervals of 15, 30, and 60 seconds. Regardless of the time interval, they found stronger associations between species than expected by chance alone. Looking to explain these associations, the found species’ wing lengths and the similarity of their calls were the most important factors. In contrast, birds that “buddy up” during stopovers were not maintaining those relationships in the air, and they were not necessarily flying with closely related species or birds that shared their preferences for specific habitats.