When I was in Idaho this past summer, on a river rafting trip, I was lucky enough to see this guy, literally, struting his stuff! This is a blue grouse (Dendragapus obscurus) he was showing off his sexy eyebrows and puffed red airsacs to this demure little lady. Note that this smart lady is in a patch of poison ivy. And, that she has just stopped eating it to make sure I don't get too close!
Incidentally, the lady was showing some cool gular fluttering. This, I learned in Avian Biology, is because birds can't sweat. So, because it was bloody hot in Idaho, the lady was fluttering the skin on her throat to cool down. I'll try to remember to post the video I have of her doing just that.
For many types of grouse, this display would be performed by the male for several females on a lek. A lek is a place where the males get together to strut their stuff. We only saw one male, but the evening before this amourous display, we saw at least two ladies around the campsites. I'm not sure if the blue grouse leks, but my bird book says that sometimes these displays are performed in trees! The male also sometimes 'hoots'.
I haven't read any studies on these birds, but I'd guess that the hoot is a measure of size. With most animals, their body size is the limiting factor when it comes to making deep sounds. This guy's hoot was pretty deep and booming. He might be saying "Listen to me! I'm so big and sexy" ;)
