11 distinct calls is something a rote automaton could easily cope with. So I don't think this study proves much of anything about birds' cognitive abilities.
Yeah I think there's a lot of science news about how plants are capable of more than the average person thinks, but people tend to conflate that with some kind of conscious experience.
fortunately, there is a lot of evidence behind plant's feeling and thinking; enough so that if you were to expose yourself to it, and if you were willing to update your beliefs based on strong scientific evidence, I believe you'd change your view.