I believe these are Cooper's Hawk chicks though I can't be 100 percent certain. I saw the nest when they were close to fledging with half feather and half down. Within six days they were mostly feather and were busy preening all the down clumps out. Both fledged a week from the first photo.
Taken on 7-11. Hawks seems comfortable on one foot with the other drawn up in front of it. The first time I observed this behavior years ago I thought it was maybe an injury, but it's actually quite common.