Today, the fledgling robins have graduated from their nest. Two of them are sitting on the wooden swing set in the back yard, hunkered down, looking fat and a little bit scared. They obviously ad to fly there from somewhere, but there is definite body language in the way the one of them is hunkered down.
"Gravity. It's the law."
So, the "law" abiding birds are sitting solidly, occasionally stretching to full height, but soon returning to their impression of immovable stones. Even the squirrel, who has started to climb up to were the birds are lurking doesn't startle them into flight.
Something else does. Big Mamma's here.
The adult robin settles herself on the cross bar of the swing set. She doesn't make any obvious moves, but the younger birds look less stable, less determined to remain where they are. Maybe it isn't Big Mamma--maybe it's the kind of stereotyped thug, issuing vague threats. "Ya know, it'd be a shame, something happened to somebody who hung around dis here swing set. Yah. A real pity, ya know?" Because there. . . they. . .go.
The most reluctant one just took off, and glided across the yard to poerch at roughly the same height over on the privacy fence across the garden. And hunkered down again.
UPDATE: It's not Big Mamma, or Guido Soprano--it's the avian personal trainer! She found the Reluctant One and proceeded to chivvy him u p and down the fence. But he's more nervous of flight than he is of her, and he's resolutely remaining where he is. Perhaps learning to fly is like learning to ride a bike without training wheels. You have to want to GO more than you want to STAY.