Interesting. In season, we often have Channel-billed Cuckoos[0] fly past here in Sydney. The other birds chase them out. First you hear a cacophony of bleating, and then you look up and see a chain of 5-10 angry birds of multiple species chasing the cuckoos away. Next time I see that I'll think of this paper. I think if you had just asked an aboriginal person, or anyone that actually has an awareness of nature, this was common knowledge. It never occurred to me to articulate it as an evolutionary trans-species vocalization with reference to linguistic development, though. I guess now we can prove that inter-species coordination through vocalization has evolved separately to that of primates, which intellectually should help to keep us humble. That said, monosyllabic bleating is hardly Chekhov.

[0] https://en.wikipedia.org/wiki/Channel-billed_cuckoo