Iridescence

The iridescence on a Tree Swallow's feathers is just so beautiful, I never get tired of seeing it. Have to admit, though, that there are an awful lot of these birds, everywhere : ) This is one of the birds that has taken over a particular Mountain Bluebird nest box recently. I was photographing the Bluebirds, including one of the babies that was looking through the nest box hole, and then two days later, I found that the nest box had been taken over by Tree Swallows. Totally missed the fledging of those youngsters : ( Taken along a backroad SW of Calgary, on 2 July 2013.