I'm glad that this behavior has been defined! We've had 3 rescued hens for a couple of months now (our first chickens) and initially only Ruby, who's at the bottom of the pecking order, did this little squat. Now all 3 do it. It makes sense now and had assumed that's what was going on. My husband like to scritch them under their wings, which makes them really fluff up and shake! They're adorable