Friday, January 24, 2003
Carolina wren plumage is rusty brown on the crown, back, and tail, with a distinct white or light buffy line above the eye. The two sexes look similar (at least to humans) although the male is reported to be slightly larger overall. It is the largest wren in the east, and is the wren most likely resident in Carlisle during winter. It is a very active bird, often seen poking its bill into every nook and cranny. According to Gruson, the genus name Thryothorus is Greek meaning "reed-leaping," and alludes to its preference for being near water; the species name ludovicianus is Latin, meaning "of Louisiana."
We first saw a Carolina wren in Carlisle in our back yard in 1990, although Christmas Bird Count (CBC) records show that they were here in the early 1980s. Wren populations decline in years with severe winters, which may account for the lack of sightings during the 1996 and 1997 Carlisle CBC (see graph, courtesy of Ken Harte). Their numbers have steadily increased in recent years, probably due to warmer winter temperatures and the increasing popularity of bird feeders.
Robert Stymeist, a Watertown birder, has a goal of finding a Carolina wren in every city or town in Massachusetts. As of last December, he had tallied a Carolina wren in 260 out of 351 towns, and is missing only Ashby in Middlesex County. Quoting Stymeist, "I have found that the best places to search for wrens are areas with people, thickets, and water. Cemeteries are often good places to look for wrens." (Perhaps because they like people?)
About 95% of the diet is animal material such as insects, spiders, sowbugs, and millipedes; it also includes small vertebrates such as tree frogs. They will also eat small fruits and some seeds. The pair of Carolina wrens which frequent our yard is particularly fond of suet and sunflower seed, especially sunflower hearts. They usually visit all of our feeders, which hold different seed mixtures, suggesting that they occasionally eat seeds other than sunflower.
Pairs remain together all year and defend permanent territories. There are often two broods in the north and sometimes three in the south. According to Harrison, the nest is built in a natural cavity, bird house, upturned tree root, stone wall, under a bridge, or an out-building, and is seldom more than 10 feet above ground. The female lays 4-8 eggs, and commonly 5-6. When we visited Louisiana, we visited a campground and discovered a nest built in a charcoal grill! (Hopefully, this did not result in hard-boiled wren eggs.) Birders who post on Massbird.org (an e-mail list-serve) have reported a variety of peculiar nest sites including a flowerpot, under a propane tank lid, inside an overturned canoe, and even in an active mailbox. Traditional nest boxes seem relatively unpopular.
Last summer, we saw a pair of wrens in our yard with 2 or 3 young, the first evidence of breeding on our property, although they've been around our house for over 10 years. During the recent cold spell, they seem to be keeping their forays to a minimum, staying under our addition and making frequent visits to the suet feeder.
1. Ehrlich, Paul R., David S. Dobkin, and Darryl Wheye, The Birder's Handbook, A Fireside Book Published by Simon & Schuster, 1988, pp. 440.
2. Harrison, Hal H. Birds'Nests, Peterson Field Guide Series, Houghton Mifflin Co. 1975, p. 150.
3. Gruson, Edward S., Words for Birds, Quadrangle Books, 1972, p. 202.
4. Stymeist, Robert H. "Wren Quest", Bird Observer, Vol. 30, No. 6, 2002, pp. 424-431.
5. Thanks to many Massbirders for descriptions of "funky" wren nest sites.
Tom Brownrigg is a member of the Carlisle Conservation Commission. His interests include birding, nature observation, and digital photography.
Submissions for the Biodiversity Corner are encouraged and welcomed from all interested observers of nature. Think of it as your space to say a word or two on behalf of one of your favorite species. Just follow the format of today's column (or not) and send to Kay Fairweather at 392 School Street, Carlisle MA 01741 or to email@example.com Don't hold back due to lack of photos or drawings.
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