With lots of patience, I managed to get a pair of Mountain Bluebirds catching various caterpillars, spiders and unrecognizable insects to feed to their young ones. This beautiful lady showed off her interesting and colourful catch before it was dropped into the wide-open mouth of one of her babies in their nest box. Taken on 15 June 2013, SW of Calgary.

In Bluebirds, the blue colour is produced by the structure of the feather - there is no blue pigment. "Tiny air pockets in the barbs of feathers can scatter incoming light, resulting in a specific, non-iridescent color. Blue colors in feathers are almost always produced in this manner. Examples include the blue feathers of Bluebirds, Indigo Buntings, Blue Jay's and Steller's Jays."

www.allaboutbirds.org/guide/Mountain_Bluebird/id

www.jstor.org/discover/pgs/index?id=10.2307/4077277&i...