Comfy & Safe: Clues
Do you see the white eyelid? This male robin has his eyes closed. That's a big clue that he feels very safe and comfortable as he preens. He's not asleep; robins don't sleep with their head in their breast. They turn their head and tuck their beak into the feathers on their back when they sleep. Healthy birds spend a lot of time preening—once or many times every day. (Sick birds get a lot of mites because they don't feel well enough to preen.)

While he's preening, Robin looks plump because he's making his tummy and breast feathers stick out. Each feather is hooked to a tiny muscle. The robin can control each of those individual muscles. The feathers need to stick out for cleaning. He runs his beak through and scrapes off any dirt on the feathers. Here you can see the center line, where the feathers part and grow either over the left pectoral muscles or the right pectoral muscles.

Image: Don Severson