[Length 5 in. Wingspan 8.25 in.]

This Mexican Chickadee was photographed on Rustler Peak in southeastern Arizona, USA. Photo taken with a Nikkor 300mm ED f4.5 lens on Ektachrome 400 film pushed to 800. This photo is on file with the Academy of Natural Sciences' Visual Resources for Ornithology (VIREO B22/1/009). (Date: May 1985)

[Length 5.25 in. Wingspan 8.5 in.]

This "Western" Mountain Chickadee was photographed at Sequoia National Forest, California, USA. Photo taken with a AF-S VR Zoom-Nikkor 80-400mm f/4.5-5.6G IF-ED lens on a Nikon D7100 camera. (Date: July 2, 2013)

[Length 5.25 in. Wingspan 8.5 in.]

This Western Wood-Pewee was photographed at Sequoia National Forest, California, USA. Photo taken with a AF-S VR Zoom-Nikkor 80-400mm f/4.5-5.6G IF-ED lens on a Nikon D7100 camera. (Date: July 5, 2013)

[Length 5.25 in. Wingspan 8.5 in.]

This "Pacific" Mountain Chickadee was photographed in the mountains near Mt. Pinos, California, USA. Photo taken with a Nikkor 300mm ED f4.5 lens on Ektachrome 200 film pushed to 800. (Date: August 1983)

[Length 5.25 in. Wingspan 8.5 in.]

This Mountain Chickadee was photographed at the Moose Visitor Center, Gould (Walden), Colorado, USA. Photo taken with a AF-S VR Zoom-Nikkor 80-400mm f/4.5-5.6G IF-ED lens on a Nikon D7100 camera. (Date: June 3, 2016)

[Length 5.25 in. Wingspan 8.5 in.]

This Mountain Chickadee was photographed at the mountaintop restaurant, Sandia Crest, New Mexico, USA. Photo taken with a Nikkor 300mm EDAF-S VR f2.8 lens (EFL=450mm) on a Nikon D200 camera. (Date: March 3, 2008)

[Length 5.25 in. Wingspan 8.5 in.]

This "Rocky Mountain" Mountain Chickadee was photographed at Allenspark, Colorado, USA. Photo taken with a AF-S VR Nikkor 300mm f/2.8G IF-ED lens (EFL=450mm) on a Nikon D300 camera. (Date: April 21, 2009)

[Length 5.25 in. Wingspan 8.5 in.]

This "Rocky Mountain" Mountain Chickadee was photographed at Allenspark, Colorado, USA. Photo taken with a AF-S VR Nikkor 300mm f/2.8G IF-ED lens (EFL=450mm) on a Nikon D300 camera. (Date: April 21, 2009)

[Length 5.25 in. Wingspan 8.5 in.]

This Mountain Chickadee in Flight was photographed at the Trail of Time, Grand Canyon National Park, Arizona, USA. Photo taken with a AF-S DX VR Zoom-Nikkor 18-200mm f/3.5-5.6G IF-ED [II] lens (EFL=300mm) on a Nikon D7000 camera. (Date: September 21, 2011)