Thanks for the pointer to The Elegant Universe. I have a very slow dialup connection now that I've moved out to the country so I don't know how well I'll go at seeing the program, but I'll sure give it a try.

I managed to catch this one of one of the parents giving a rather half-hearted yawn. Unfortunately I'd aimed the camera so that when the unexpected yawn came, the top of the bill went out the top of the frame. :( But it gives you an idea of what it looks like. The chicks appear to stretch their mouths open a good deal further than that... pity I can't find a chick yawn just yet.