I have come across three references to animals learning a language these past few days.
The first—concerning bonobos—is in the book Ape House by Sara Gruen. I haven’t yet read it; I’m next in line after my wife.
The second was when Stephen Krashen mentioned Cosmo the talking parrot in a YouTube video.
And the third was in the book, Before Adam by Jack London (I’m listening to it in Dutch). In chapter 4 it describes how early humanoids developed language.
The same principles that apply to us apply to other creatures, apparently. And why should they not?