Saturday, August 25, 2012

Brewer's Blackbird

As we left the Seal Observation Rest Area along the Coast Highway (see previous posts), a Brewer's Blackbird called goodbye. This blackbird has an interesting nomenclatural history. Audubon collected several in 1843 along the upper Missouri River. Thinking the birds were new to science, he named them Quiscalus breweri. Thomas Brewer was a Boston physician and ornithologist. However, Johannes Wagler first published a description of the species in 1829, naming it Psarocolius cyanocephalus. The Law of Priority kicks is applied to cases like this one. The correct name is the first published one, starting with Linnaeus' 1758 12th edition of his book, Systema Naturae. Thus Audubon's scientific name is no longer with us, but his common name, Brewer's Blackbird, has survived (Martin 2002).

Prior to 1914, Brewer's Blackbirds were a western species, not found east of western Minnesota. During the next 40 years, this blackbird expanded its range east (at least 1200 km) and north (some 300 km). Conversion of forest to agricuiltural land is cited for the reason. Now the species is common in the winter in the southeastern United States (Martin 2002). Brewer's Blackbirds and Common Grackles compete where their ranges overlap. Apparently Brewer's Blackbirds prefer grasslands, whereas grackles thrive in urban situations.

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