Saturday, May 10, 2014

Song Sparrow

Heermann's Song Sparrow (Melospiza melodia heermanni)
Heermann's Song Sparrow (Melospiza melodia heermanni)
April 20, 2014. Mission Trails Park, San Diego, California. Greg Gillson.
Having lived and birded in the Pacific Northwest for for several decades, I am used to observing the variation in different populations of Song Sparrows. You see, beginning and visiting birders often mistake the dark rusty Song Sparrows of the temperate rain forests of the NW for Fox Sparrows. Song Sparrows, though, have gray and rusty head stripes that the wintering Sooty Fox Sparrows lack.

There have been as many as 52 named subspecies, now generally whittled down to 32 (Birds of Oregon: a general reference (2003)) or 24 (Wikipedia), in 5 major groups. However, these show a cline, a gradual and continuous change from one form to another. Songs, though, are pretty much the same across the range.

Heermann's Song Sparrow (Melospiza melodia heermanni)
Another view of the bird above.
The variation in physical appearance follows part of Gloger's Rule: birds in humid areas are often darker than birds in drier regions. Thus, these southern California birds pictured above are paler and brighter than the birds in the Pacific Northwest (below).

Rusty Song Sparrow (Melospiza melodia morphna)

Rusty Song Sparrow (Melospiza melodia morphna)
November 27, 2008. Forest Grove, Oregon. Greg Gillson.