Another smoky day here in Calgary (21 July 2017), with a temperature of 20C this morning and cloudy. The air quality yesterday was expected to reach High Risk, but it seemed to be bearable late in the afternoon. So, I took a drive along some of my favourite roads SW of the city, seeing a few of the 'usual' things. I really hope that rain will arrive soon to help the firefighters in British Columbia and in Alberta, too! So much devastation.

This photo is of one of my 'usual' Mountain Bluebird females. I'm not completely sure, as I haven't been able to get there much recently, but I suspect that they have had a second set of young ones. Dad appeared while I was there, carrying a huge caterpillar in his beak. I was so happy to see them, even more so as I haven't been seeing all that much in the way of birds recently. Sorry if you are tired of seeing Bluebird photos!

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...