Do you guys have Cardinals? We have a lot of them here and I have noticed something pretty cool from one here. He makes this call, and the first time through, he does 0 whistles at the end. He does it again, and whistles one time at the end. Then he does it again and whistles twice. Then 3 times, 4, 5, etc, all the way up to about 10 times. I've never heard a wild bird count like that, but he does it every morning, and never miscounts. He always starts at 0 and goes to at least 8 before flying away. I just thought this is kinda weird behavior. I'm 52, and never noticed this before now. This I believe is the same Cardinal that returns every year with his mate to nest in a bush out back. They always nest on the same branch of the bush too. Fascinating pair of birds. I'll try to get you guys some pics. I never have my phone out there.
Funny enough, if you watch the end of this vid, right after Breydon signs off, this is the same bird in the background, doing the same call. He has many calls, but this one is the one where he counts. He counts to 10 in end of this. But if you pay attention before that, he counts to 9.