The blue jays around my yard make a particular toot when a human gets too close. It's reliable enough that I know someone is walking by the house whenever I hea

The blue jays around my yard make a particular toot when a human gets too close. It's reliable enough that I know someone is walking by the house whenever I hear it. (There is not a lot of foot traffic here.) They don't seem to make the same noise for dogs and cats. The squirrels are better dog and cat alarms. I've pondered whether the toot might mean "human" or "oh shit" or something else. Supposing it is denotational like "human", I'm also very curious if different populations of blue jays use vocalizations differently in places with different threats. That would imply the sounds are taught and learned, which I'd say is a stronger indicator of language than, say, sounds that are instinctively understood but happen to be compositional.