House Wren Photo © Gary Mueller/PFW

A plain brown bird with an effervescent voice, the House Wren is a common backyard bird over nearly the entire Western Hemisphere. Listen for its rush-and-jumble song in summer and you’ll find this species zipping through shrubs and low tree branches, snatching at insects. House Wrens will gladly use nestboxes, or you may find their twig-filled nests in old cans, boots, or boxes lying around in your garage.

Habitat	Food	Nesting	Behavior	Conservation
Open Woodland	Insects	Cavity	Foliage Gleaner	Least Concern

Cool Facts

• The House Wren has one of the largest ranges of any songbird in the New World. It breeds from Canada through the West Indies and Central America, southward to the southernmost point of South America.
• House Wrens nest inside tree holes and nest boxes. As the season progresses their nests can become infested with mites and other parasites that feed on the wren nestlings. Perhaps to fight this problem, wrens often add spider egg sacs into the materials they build their nests from. In lab studies, once the spiders hatched, they helped the wrens by devouring the nest parasites.
• A House Wren weighs about as much as two quarters, but it’s a fierce competitor for nest holes. Wrens will harass and peck at much larger birds, sometimes dragging eggs and young out of a nest site they want – even occasionally killing adult birds. In some areas they are the main source of nest failure for bluebirds, Tree Swallows, Prothonotary Warblers, and chickadees.
• For House Wren eggs, temperature inside the nest box can be critical to survival. If a sun-drenched nest box warms above about 106 degrees Fahrenheit for an hour, the eggs will begin to die. If a cold snap chills a nest below about 65 degrees Fahrenheit for more than a day it can also doom the eggs.
• Male House Wrens returning north to breed in their first year are more likely to settle close to an established male than farther from it. Experienced males tend to settle farther apart. Young males may take clues from more experienced males about what areas are good nesting sites.
• The oldest known House Wren was nine years old.

Habitat

Open Woodland

Food

Insects

Eats a wide variety of insects and spiders, including beetles, caterpillars, earwigs, and daddy longlegs, as well as smaller numbers of more mobile insects such as flies, leafhoppers, and springtails. Also eats snail shells, probably for the calcium they contain and to provide grit for digestion.

Nesting

Nest Description

House Wrens pile twigs into the cavities they choose to nest in, either to make a bed on which to build a soft-lined cup, or sometimes mounded up into a barrier between nest and entrance, seemingly to protect the nest from cold weather, predators, or cowbirds. The cup itself is built into a depression in the twigs and lined with just a few grams (less than 0.25 oz) of feathers, grasses and other plant material, animal hair, spider egg sacs, string, snakeskin, and discarded plastic.

Nest Placement

Cavity

House Wrens nest in old woodpecker holes, natural crevices, and nest boxes (or discarded tins, shoes, etc.) provided by humans. This bird’s association with open woodland is reflected in its choice of nest sites: it rarely uses nest sites more than 100 feet from woody vegetation, but also avoids heavily wooded nest sites where it’s hard to see predators coming. Despite their small size, they can be fierce competitors for nest sites, sometimes evicting a larger species and claiming its cavity after the bird has already begun nesting.

© René Corado / WFVZ		© René Corado / WFVZ

Behavior

Foliage Gleaner

A busy forager in low tree branches and shrubs. You’ll occasionally see these birds flit across openings with steady, level flight, or investigating the ground with quick hops. Male House Wrens start building several nests at once in hopes of persuading a female to mate with him. Pairs typically break up by the end of each nesting season and choose new partners the next year. House Wrens are aggressive. Single males sometimes compete for females even after a pair has begun nesting. In about half of these contests the outsider succeeds in displacing his rival, at which point he usually discards any existing eggs or nestlings and begins a new family with the female.

Conservation status via IUCN

Least Concern

House Wren populations have experienced some declines, notably in the northeast areas of their U.S. and Canada range, but generally from 1966 to 2010 populations have been stable and slightly increasing, according to the North American Breeding Bird Survey. Partner's in Flight estimates the total breeding population at 160 million with 19 percent spending some part of the year in the U.S., 9 percent in Mexico, and 8 percent breeding in Canada. They rate a 5 out of 20 on the Continental Concern Score and are not on the 2012 Watch List.