Recently I posted images of the new crop of House Finches in the park. Although those were “newly hatched” for the season, they’d been out of the egg long enough to lose the baby hairs on the top of their heads. Then I saw this newer arrival in a shrub in the Native Plant Area. The “hairs” of course are really feathers. This bird was able to fly. It had probably been out of the egg a couple of weeks. I couldn’t find a source that theorized the function of those pin feathers on the bird’s crown or estimated the age at which a hatchling lost them.