I don't think it's true but remember that decoding animal language is ridiculously hard. Our understanding of it is basically "play sound - see what animals say". And even that is nontrivial as the article points out.
... and then I realize that the dolphins in the comic are repeating: "hey, do you speak spanish?" and "what's up?" in spanish to the humans... brilliant.
Relevant farside comic: http://i.imgur.com/QSR2AfI.gif