Who was Cassin?

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Rounding out the solitary vireo complex is the third species that is found in the far west: Pacific Northwest south to Mexico and Central America.

If you imagine the blue-headed vireo with yellowish-green flanks and then the plumbeous vireo without, then the intermediate form with just a little yellow on its sides is the Cassin's vireo.

But, this begs the question: Who was Cassin?

Most have heard of John James Audubon and many know the name Alexander Wilson. Both had similar goals: finding and drawing all the species of birds that live in this country. Wilson's nine-volume American Ornithology (1808–1814) contained 268 species of birds, 26 of which had not previously been described. Audubon's The Birds of America, (1827–1839), considered the finest ornithological work ever completed, had 497 bird species with Audubon identified 25 new species.

John Cassin

But neither man spent much time, or any time, west of the Rockies. That's where Cassin enters the picture. 

John Cassin (1813–1869) was America's first taxonomist, describing 198 birds not previously mentioned by either Wilson or Audubon. Cassin's widely distributed publications include Illustrations of the Birds of California, Texas, Oregon, British and Russian America (1856), a handsome octavo volume depicting 50 species not described by John James Audubon.

Cassin's vireo is named in his honor, as well as are Cassin's auklet, Cassin's sparrow, Cassin's kingbird and Cassin's finch. 

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