The Carlisle Mosquito Online

Friday, December 1, 2006

Features

Biodiversity Corner
American Tree Sparrow

(Photo by R. Hays Cummins, Miami University)
Name. The American Tree Sparrow is Spizella arborea. This name is not the best fit, since Spizella means finch and arborea is derived from the Latin word for tree and the bird is in a different family from the finches and it is not a forest bird — it prefers open areas with low growth and few trees. Its common name is based on a resemblance to the Eurasian Tree Sparrow. The name "sparrow" is a better fit; it is from the old English word spearwa which meant flutterer, and while the name doesn't discriminate, it is somewhat descriptive.

When and where seen. Tom Brownrigg saw some American Tree Sparrows on November 4 at the O'Rourke Field, in their typical brushy habitat. The earliest he has noted them in Carlisle is October 30 and the latest is April 17. They breed in the low-Arctic tundra and return to our latitude for the winter. You will see them in groups of four to eight, in weedy over-grown places.

Distinguishing characteristics: Sparrows can be difficult to identify because there are several similar species, and within a species the plumage varies with maturity and season. There were song sparrows and white-throated sparrows in the same area where Tom saw the tree sparrows. The best distinguishing mark for the American Tree Sparrow is the dark spot in the middle of the otherwise gray breast — and I'm guessing the streaky-breasted song sparrows would be the ones singing "Non, je ne regrette rien" à la Edith Piaf, the French singer known as "the little sparrow."

The American Tree Sparrow has a distinctly rufous crown (like the Chipping Sparrow), a rufous eyeline, and a bicolored bill in which the upper mandible is dark and the lower one is yellow. We have Chipping Sparrows here but they are seldom seen at the same time as American Tree Sparrows. Chipping Sparrows breed in our area but go south for the winter and are usually gone by the time the tree sparrows arrive from the north.

Food. The American Tree Sparrow feeds mainly on seeds but also takes a few insects and spiders. It forages on the ground, is known to shake seeds from old flower stalks sticking up through the snow and, of course, it visits bird feeders.

Sources. David Allen Sibley, The Sibley Guide to Bird Life and Behavior; National Park Service web site at www.nps.gov (search on Tree Sparrow); http://birdsbybent.com; Ken Harte for the Christmas Bird Count chart, R. Hays Cummins of Miami University of Ohio for the photo (there are additional tree sparrow photos as well as song sparrows and white-throated sparrows at http://jrscience.wcp.muohio.edu/birds/ohio_birds/toc.html).

Perhaps it is not surprising that such excellent photos of a sparrow whose name is finch came from the web site for Miami University which is located in Ohio.

This 25-year view of the American Tree Sparrow's appearance in the annual Christmas Count shows ups and downs that are inexplicable. (Chart by Ken Harte)

Submissions for the Biodiversity Corner are encouraged from everyone. Send your ideas, your nature photos, or the whole column to Kay Fairweather at 392 School Street, Carlisle MA 01741 or to kayfair@comcast.net.


2006 The Carlisle Mosquito