Western Bluebird

Sialia mexicana
Range Map

The Western Bluebird breeds in semi-open country, excluding desert areas in western North America (British Columbia to central Mexico). Incapable of excavating the cavities they depend on for nesting, they rely on woodpeckers to supply their summer homes. Man-made bird houses have helped these birds overcome the fierce competition for natural cavities.

Research shows that 45% of studied nests held young birds that were not fathered by the male member of the nesting pair. Further, 19% of all the young were products of extramarital unions.

These birds spend winters in California, southwestern USA and northern Mexico.

Today’s science recognises six subspecies of Western Bluebirds. Because there is much variation within each breeding population, it is difficult to identify the point of origin for some wintering birds:

  • S. m. occidentalis breeds along the Pacific Coast from British Columbia.
  • S. m. bairdi breeds in the North American interior from Utah and Colorado and south into northern Mexico.
  • S. m. jacoti is resident from Texas Hill Country (Davis Mountains) south to northern Mexico.
  • S. m. amabilis is resident Mexico (Chihuahua and Zacatecas).
  • S. m. nelsoni is resident in central Mexico (Coahuila, Guanajuato, and Jalisco).
  • S. m. mexicana is resident in southern Mexico.

I have a fondness for juvenile bluebirds, and most of my experience has been with Western Bluebirds, which is the Sialia species I’ve most photographed. I find their soft jumble of colors and their inquisitive nature endearing.

One of my favorite memories of these birds came late December 2020 after crossing the New Mexico-Texas border near the Guadalupe Mountains. I spent the afternoon of the 27th at at Pine Springs Camp, scouting the lower slopes of the creek’s canyon. The weather must have recently warmed and melted snows up-slope, because an old dirt road upstream from the camp was awash in a few inches of clear flowing water. Early the next morning, I hiked up this, now mostly dry roadway and found a depression at the foot-trail crossing the road that held a shallow pool. A variety of birds gathered to bathe and drink, so I sat on my folding stool and melted into the background as best I could, and enjoyed the show for a few hours. The Thrush clan was well represented, and included Western Bluebirds, Eastern Bluebirds, Hermit Thrushes, American Robins, and Townsend’s Solitaires. Thrashers, sparrows, juncos, verdins, shrikes, towhees, flickers, chickadees, joined the gathering flocks to enjoy the now shrinking pool. There were a dozen or more Mule Deer interested in the water as well, and because I remained still, manning my camera, they weren’t sure of my location, but their caution told me they had a sense of my presence. At last, several groups approached. One member was a large buck in his prime. I could hardly contain my excitement.

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