House wrens are small, busy songbirds that can be found across much of North America. They get their name from their tendency to nest around human homes and structures. House wrens build nests in all sorts of nooks and crannies around houses, barns, garages, sheds and more. But what exactly are their nesting habits and preferences?
Nesting Sites
House wrens are very adaptable when it comes to choosing nesting sites. They will nest in natural cavities like old woodpecker holes, as well as a wide variety of human-made sites. Some of their favorite nesting spots around homes include:
- Holes and cavities in walls
- Spaces under eaves
- Inside lampposts or porch columns
- Rain gutters
- Vents
- Mailboxes
- Hollow fence posts
- Bird houses
- Boxes, cans, buckets or other containers
- Old boots, pots, kettles or other discarded items
- Inside barns and sheds
- Behind shutters or signs
- Garages and carports
House wrens are not very picky about the exact nesting spot as long as it provides a protected cavity. They typically choose cavities that are around 1.5-8 inches across. They also prefer sites that are 5-15 feet above ground, likely to help avoid predators.
Nest Construction
The male house wren does most of the nest construction, using sticks, grass, feathers, bark, paper, cloth and other soft materials he can find. The nest consists of a loose cup made of twigs, then lined with softer material. House wrens will sometimes incorporate odd items from around homes into their nests like paper scraps, candy wrappers, rubber bands and more.
House wrens are also unique in that they frequently build dummy or decoy nests in multiple sites around their territory, even ones totally unsuitable for raising young. The male seems to build these extra nests to attract a mate and provide options for egg-laying and breeding. Even after eggs are laid, he may continue building unused nests throughout the breeding season.
Ideal Nest Boxes
Many people specifically put up nest boxes to attract nesting house wrens. If you want to put up a house wren box, here are some tips:
- Use a box 4-6 inches in diameter.
- Make sure the entrance hole is no more than 1.5 inches across.
- Add internal perches or ridges for the wrens to sit on.
- Face the hole away from prevailing winds and rains.
- Mount the box 5-15 feet above ground.
- Consider predator guards if in an open area.
- Use plain wood with a light exterior color to limit heat gain.
- Have a removable front to easily clean out old nests.
When Do They Nest?
House wrens can raise multiple broods in a single breeding season. Here is an overview of their typical nesting timeline:
- Early spring: Males arrive at nesting sites first and establish territories through loud song. They choose multiple nest locations and build dummy nests.
- Mid spring: Females arrive and select a nest. Males continue building unused nests after mating occurs.
- Late spring: Eggs are laid and incubated for 13-15 days. The female cares for the young, which fledge after about 16-18 days.
- Early summer: First broods leave nest. Females typically lay a second clutch and the process repeats.
- Mid summer: Second broods fledge. Some pairs may raise a third clutch before the season ends.
- Late summer/early fall: Nesting season wraps up. Wrens depart for southern wintering grounds.
The exact nesting timeline varies across the house wren’s range. They may start as early as April in the south or as late as May or June in the north. Most nesting and brooding occurs from May through August.
Other Interesting Facts
Here are a few more fascinating tidbits about house wren nesting behaviors:
- Females almost always choose the highest quality male’s nest to lay eggs in. Unused nests are left empty.
- House wrens are aggressive about defending their nest sites. They may harass, peck or even dismantle other birds’ nests in their territory.
- If a nest is disturbed, especially with eggs or young inside, the wrens may abandon it completely.
- House wrens nest at lower densities than many birds due to their large territories and nest site competition.
- The male continues bringing food to the female during incubation and to the nestlings as they grow.
- Parents may “scold” loudly or dive-bomb intruders near the nest to defend their brood.
Conclusion
House wrens exhibit some very unique and interesting nesting behaviors. Their ability to use a wide array of nesting sites allows them to thrive near humans. Following their nesting timeline and habits can provide a fascinating look into the breeding biology of these common backyard birds.