Once, while walking through the woods behind my house, I heard the familiar sound of a chickadee and spotted one in the trees close by. It stayed there long enough for me to make a few photos. I later identified it as a boreal chickadee.
I have been using The Cornell Lab of Ornithology – All about Birds site to help identify birds. You can check their entry on the boreal chickadee at: http://www.allaboutbirds.org/guide/Boreal_Chickadee/id