The chicks in this picture are approximately 12 days old. This is the last image of the chicks in the nestbox. To open the nestbox after the chicks are more than 12-14 days old may result in pre-mature fledging which could reduce their chances for survival. I believe the last chick fledged July 6th (approximately 20 days after hatching). Judging by the coloring of the chicks (males typically show more blue color at this age) I believe this clutch consisted of 2 females and one male. Hopefully I will be seeing the chicks at the feeder soon!