Baby Chickadees

Just today we became aware that we had baby Black-cappedChickadees.  If you look closely you can count four.  We have been seeing some activity at the bird house for a number of days and were under the impression and hoping that they were building a nest.  Wrong, the nest had already been built, eggs laid, incubated, and hatched.  How could we have missed so much?  In past years this box has been used by Violet-green Swallows, and they are easy to spot with their long graceful swoops, and aerial insect catches.  After hearing the babies today and then watching closely, I realized the Chickadees have a much shorter exposer time.  They make a quick dart from the protection of the cherry tree a few feet away and enter directly into the bird house. Upon exiting they fly directly into the nearby fir trees and disappear to search for insects completely out of sight.  Swallows on the other hand, after their long swoops, land on the outside of the bird house hole and pause briefly before entering. Upon exiting they resume their swooping flight in full view for yet another insect.