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Creating a Wild Backyard: Wrens of Maryland

A cheerful song in threes (the Carolina wren says "teakettle, teakettle, teakettle!"), a pert tail that is often held straight up, and a slightly downward curving beak make the wren unmistakable among birds.

Wrens are in the bird family known as "Troglodytes", which is Latin for "Creeper into holes" and "cave dweller", an apt name for a bird that nests in almost any small cavity. Besides bird houses and old woodpecker holes, these birds have been known to nest in spools of string, fishing creel hung in sheds, boots and shoes, pockets of clothing, hats, and flower pots, just to name a few!

Natural History
Wrens begin nesting from March through August and can raise two broods in one season. Male wrens build many nests, sometimes as many as five or six, for their intended mates. Biologists think this may be the male wren's strategy for keeping other birds from nesting in his territory. This is sometimes a problem along bluebird nest box trails, where the numerous wren nests discourage bluebirds from nesting and it is not legal to remove wren nests from bluebird boxes! Wrens are protected by law and may not be taken or harassed and their nests may not be destroyed. Wrens lay four to nine eggs which hatch in about two and a half weeks. The young leave the nest about two weeks later.

Kinds of Wrens
House wrens are Maryland's most common wren species and the one most likely to nest in a backyard nest box. These wrens like to live in deciduous woods and wood edges, backyards, parks, and gardens. House wrens mostly migrate south in the winter, but may sometimes hang around after the first frost if suet is offered in feeders, although it is rare for wrens to stay in Maryland through Christmas. Male wrens arrive back in Maryland before females so that they can begin building a choice of nests for the female. When the females arrive, they choose their nests and lay their eggs. Surprisingly, house wrens have been seen feeding and caring for the young of other species. House wrens, like all wrens, are primarily insect eaters and favor the gypsy moth, which can injure backyard and forest trees.

Carolina wrens are year-round residents in Maryland. This is the largest wren in the eastern United States and it is reddish brown in color, with a distinctive white streak over the eye and a buff colored underside. Sometimes called the mocking wren, Carolinas often mimic the sounds of other birds but are best known for their "teakettle, teakettle, teakettle" and "cheery-cheery" songs.

Marsh and sedge wrens migrate through most of Maryland but are found year-round in marshes on the Eastern Shore. Marsh wrens prefer cattail marshes, or bulrushes and reeds of tidal creeks, coastal salt and brackish marshes as well as inland river valleys. Sedge wrens prefer sedge and freshwater meadows where grasses and sedges grow with scattered shrubs. Both wrens build nests that are well hidden, and sometimes nest in colonies with other wrens. Marsh wren females build their nests mostly by themselves, but the males still follow wren tradition and build a series of dummy nests before and after the female arrives. These two wrens are unlikely to nest in boxes.

Winter wrens summer in cool forests and swamps in the Northeast U.S., including our own Garrett County. They migrate south in the fall, but can also be seen in Maryland during the winter. These wrens are found near brush piles and the edges of swamps. Like other wrens, they primarily feed on forest insects, including bark beetles, weevils, borers, and the moths of spruce budworms. They also eat Eastern red cedar fruits.

Bewick's wrens were so named by Audubon for his friend Thomas Bewick, an English artist and wood engraver. The decline of the Bewick's Wren in Appalachia has been a major concern of the Maryland Natural Heritage Program, which monitors the status of rare plant and animal species in the State. Since 1986 the Bewick's Wren has been classified as endangered under regulations of the Maryland Endangered Species Act of 1971. This classification provides important status for the species, protecting the wren from many human-caused forms of disturbances. Unfortunately, with no breeding Bewick's Wrens known to be left in the State, this protection may have come too late.

How to Build a Wren Nest Box

Materials

• 1" X 6" X 4' lumber

• 1 1/2" galvanized nails

Construction

1. Mark and cut pieces out of lumber

2. Cut entrance hole 1 1/8" in diameter, one inch from the top of the front piece.

3. Drill 1/4" holes in the bottom piece for drainage.

4. Drill 1/4" holes near the tops of the side pieces for ventilation.

5. Assemble

Wren Nest Box Illustration for Cutting & Assembly

Wren Nest Box Tips

• Do not put a perch under the opening in the front piece. Wrens will not need a perch to get into their nest box. Starlings will sometimes use perches to rest on while trying to increase the size of an opening into a nest box.

• The size of the entrance hole will allow only wrens and similar sized or smaller birds like chickadees and nuthatches inside. Larger birds, like house sparrows or starlings will not fit through the hole. The entrance hole can be cut wider than it is tall - about 1/4" tall and 2 1/2" wide, so that the wrens can more easily fit through with the sticks and other material for their nest.

• Clean out the nest box after the young have left so that another brood can be raised. Wrens will tend not to use the same nesting material twice and so will make a second nest elsewhere if you do not clean it out.

• Place the nest box 5-10 feet above the ground, under the eaves of a building or a tree limb. Wren boxes can be firmly fixed to the side of a building or tree or can be hung freely from a wire.

• To help attract wrens, offer suet, peanut butter or meal worms in feeders.

• Of the wren species that live in Maryland, only house and Carolina wrens will nest in boxes.

For Additional Information, Contact:
 
 Wild Acres Program
 Maryland Wildlife and Heritage Service
 Attn:  Marilyn Mause
 Gwynnbrook WMA
 3740 Gwynnbrook Ave
 Owings Mills MD 21117
 410-356-0941
 E-Mail: customerservice@dnr.state.md.us

Invite Wildlife to Your Backyard...

Illustration Courtesy of Criselle Anderson