At one point or another, most of my birds have done the "skirt dance". Who do I mean by most? Petey, Joey, Piper, Pixel and even Zuri. I think Léa is still too young for that.
That leaves Shade. Shade who in the eight years (almost nine!) that I have had her has never shown any inclination towards that behaviour. I wasn't upset about it, quite frankly I was happy, as I thought if she doesn't feel the need to do the "skirt dance", she's probably less likely to want to lay eggs. In a way, I think she was always more focused on herself than on any biological need; Zuri would try to get some of "that" attention and she would willingly accept any food he may want to offer, but that was it. If he got more insistent she turned around and walked away from him.
So it came to a surprise to me that this morning, while sitting on my shoulder, she starts making that very specific noise and dropped her wings. Why now? This happened just as she was to go back to her cage, so that broke the "dance" mood. I'm not quite sure what triggered it, but I guess I'll have to pay extra attention from now on.