Monday, February 9, 2015

Common Yellowthroat

This Common Yellowthroat flew by the 180th Street March in nearby Dakota County last summer. I have blogged about the species before. Allow me to add today that yellowthroat taxonomy is a mess. Thirteen races are recognized by Guzy and Ritchison (1999). The problem is that few, if any, field marks are consistent within populations. On top of that, field marks tend to blend together where ranges meet.

Pyle (1997)merged the US and Canadian races of Common Yellowthroats into three groups: the Pacific Coastal, Western Interior, and Midwestern/Eastern.  Even with this merge, racial identification is, at best, tricky. Pacific birds are small, dark and dull. Pacific and Western Interior birds have a relatively wide, white band behind their black masks. This field mark is pale gray in Midwestern/Eastern yellowthroats. Although Western Interior birds may inhabit northwestern Minnesota and southeastern North Dakota, my photo clearly shows the grayish band typical of Midwestern and Eastern yellowthroats.

Why are races of birds important to understand?  Knowing how bird populations vary is essential to understand diversity. This knowledge is critical if we are intent in preserving robust and healthy ecosystems. You can not preserve what you can’t identify.

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