Snowbird
2 of the 7 encyclopedias on this shelf carry an entry for Snowbird. Both are reproduced below, so you can see where they agree and where they differ.
Aiton's Encyclopedia (1910)
a term often applied to the snow bunting or snowflake. It is a white sparrow-like bird with jet black markings. It breeds in the Arctic regions building a nest on the ground of coarse grass and moss lined with feathers. In the winter season it visits the northern United States in flocks to seek food. It feeds exclusively on seeds found in weed tops, and seems to enjoy our bright, wintry weather. The recollection of a snowstorm with a flock of white buntings careening joyously through the fields is one that lingers long in the memory. "The snowbuntings are the true spirits of the snowstorm," says Thoreau. "They are the animated beings that ride upon it and have their life in it." Another sparrow-like bird, often called a snowbird from its seeming frequency during a snowstorm, is the slate-colored junco with white outside tail feathers. It breeds and ranges farther south than the snow bunting. A snowstorm brings the juncos into one's dooryard, but the snow bunting stays afield. See Winter ; Sparrow
Collier's New Encyclopedia (1921)
the common name of the genus of birds Junco, family Fringillidæ, distinguished by their bill small and conical, the wings reaching the basal fourth of the exposed portion of the tail, and the tail slightly emarginate. The common snowbird or black snowbird, Junco hyemalis, of the United States E. of the Missouri, is 6½ inches long; grayish or dark ashy black deepest before; the middle of the breast and belly, the under tail coverts, and the first and second external tail feathers white, and the third tail feather white, margined with black. These birds appear in flocks in winter and are very tame. They are fond of grass-seeds and berries; the flesh is delicate and juicy, and is often sold in the New Orleans market.