June 21 - Feathers begin growing rapidly in the second week of development, helping chicks to achieve physiological endothermy, or the ability to maintain their own body temperature. The image shows a good view of the secondary wing coverts which are about ready to break out of their sheaths. The eyes will open some time around day 5 or 6. Both parents will keep up the feeding schedule, but the female will spend very little time brooding the chicks after they are five days old. Three minutes later, one of the young can be seen gulping it down.
Grasshoppers make up a large part of a young bluebird's diet.
June 18 - An all too common sight for feeding parents. June 17 - All four chicks seem healthy and are developing normally. Altricial birds are born small-brained, that develop quite rapidly because of the protein rich diet provided by the adults. As a result, brains of altricial birds are proportionally larger than brains of precocial birds. This display coupled with the chicks' calls will incite parental feeding.