Mountain Bluebird protecting her nest box

I finally went for a short drive SW of the city early evening on 7 May 2016. I was hoping to see Mountain Bluebirds, but my 'usual' pair don't seem to be at their old nesting box. At least, there was no sign of them yesterday, and Tree Swallows were circling around this box and the one just a few feet away. I did find a different pair, being harassed by Tree Swallows, and was able to get several distant, quick shots, including this one of the female. I should add here that I love Tree Swallows, too, and always hope that they are successful in finding a nest box. They are beautiful birds to see and photograph. See the information that gatescd29 has added in a comment box below. I had to rush out early this morning and ran out of time to add any more to my description, so am adding it this evening.

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...

I had also hoped to see a Wilson's Snipe at the usual place and I was lucky to find one standing on a fence post. Usually, these birds will stay for a while, but this one let me get a couple of photos and off it flew. It was SO good to see one again - they are one of my favourite birds to photograph. Other species seen included a Red-winged Blackbird, Yellow-headed Blackbird, a Coot, various distant ducks and an extremely distant pair of Red-necked Grebes.