Page 21 - Black Range Naturalist, Vol. 2, No. 3

shown here are most likely the nominate form, Sialia sialis sialis. That subspecies is typically found in the eastern United States. On the range map below its range is shown, in part, on the right side of the map. Note that during the nonbreeding period it extends its range west. The other possibility would be S. s. fulva which has a range which extends from southeastern Arizona south to the Isthmus of Tehuantepec. Its coloration is typically more “washed out” - contrast is diminished.
• Mountain Bluebird - Wyoming
• Mountain Bluebird - Wyoming
• Mountain Bluebird - Oregon
• Western Bluebird - Oregon
• Western Bluebird - Oregon
• Western Bluebird at Percha Dam State Park, NM
Photo galleries of these species are available as follows;
• Mountain Bluebird - Nutt Grasslands (south Black Range) • Western Bluebird - Near Hillsboro, NM
1. John Klicka and Robert M. Zink, “The Importance of Recent Ice Ages in Speciation: A Failed Paradigm”, Science, Vol. 277, 12 September 1997, pp. 1166-1169.
2. John Klicka, Gary Voelker, Garth M. Spellman, “A molecular phylogenetic analysis of the ‘true thrushes’”, Molecular and Phylogenetics and Evolution 34 (2005) pp. 486-500
Mountain Bluebird - Sialia currucoides - Photo by Bob Barnes Nutt Grasslands - SE of the Black Range
Green represents year round range while blue is nonbreeding range. Map curtosy of rbrausse via Wikipedia
By appearance you might think that the Western and Eastern Bluebirds are closely related. They are thought to have diverged in the late Pliocene or about 2.5 mya.1 It is the Mountain Bluebird which is most closely related to the Eastern Bluebird.2
Video of these species is available at the following links. (These videos have been taken over a period of several decades, so some are low resolution while others are HD. Links with larger text are to higher resolution video.)
• Eastern Bluebird - Hillsboro, New Mexico • Eastern Bluebird - Tennessee
• Mountain Bluebird - Oregon
The study by Klicka and Zink estimated the age (in millions of years) of divergence between several bird species found in the Black Range. Some of the findings are:
Eastern and Western Meadowlark Yellow-rumped Warbler
(Myrtle and Audubon) Scarlet and Western Tanager.
Indigo and Lazuli Bunting
Northern Cardinal and Pyrrhuloxia Rose-breasted and Black-headed Grosbeak Baltimore and Bullock’s Oriole
2.65 mya
300,000 ya 3.2 mya 3.3 mya 4.35 mya
2.2 mya 2.35 mya
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