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house wren

Troglodytes aedon

What do they look like?

House Wrens are small, squat birds that lack bold or characteristic markings. They have long, curved bills and are seen perching in the "wren posture" with the tail held up. Their heads, napes, and backs are almost uniformly brown with their throats and chests a uniform light grey. Some black, dark brown, or pinkish spots appear on their flanks, tails, and wings. There is a faint, white stripe above their eyebrows. They are usually 11 to 13 cm long and weigh between 10 and 12 g.

  • Sexual Dimorphism
  • sexes alike
  • Range mass
    10.0 to 12.0 g
    0.35 to 0.42 oz
  • Range length
    11.0 to 13.0 cm
    4.33 to 5.12 in

Where do they live?

House Wrens are native to the Nearctic region. During the breeding season they live from southern Canada to southern Argentina, Chile and the Falkland Islands. They spend the winter in a narrower range; the southern limits of the United States, southwestern California east to Florida and south throughout the Gulf Coast and Mexico.

What kind of habitat do they need?

In the wild House Wrens live in open, shrubby woodlands. However, they were named for their preference for small town and suburban backyards and human-made bird houses. Small wood-lots and forest edges are also well known habitats for these birds. Human farming and towns have created more good breeding habitat for the wren by fragmenting forests, which explains why the House Wren has expanded its range and numbers in North America. During the winter wrens live in thickets, shrubby and brushy areas, riparian forests, and savannas in the southern United States. In Mexico, they prefer tropical evergreen and semideciduous forests.

How do they reproduce?

House Wren nest sizes range from 4 to 8 eggs, with one egg laid per day. Females develop single large incubation patches (bare areas of skin on their bellies) and will spend over half of their time incubating the eggs, once their entire clutch has been laid. Hatching begins about 12 days after the last egg is laid and occurs only during daylight hours. House Wrens are able to breed (have reached sexual maturity) when they are 1 year old, but some first time breeders skip the regular breeding time and choose instead to breed alongside the older birds who are attempting a second clutch in a season. House Wrens nest in tree cavities, such as old woodpecker holes. They preferring cavities closer to the ground with small entrances.

  • How often does reproduction occur?
    Breeding occurs in late April to early May with the majority of nests started in mid to late May. Some females that start a nest early will sometimes make a second nest in late June to early July.
  • Breeding season
    Late April to July
  • Range eggs per season
    4.0 to 8.0
  • Average eggs per season
    7
    AnAge
  • Average time to hatching
    12.0 days
  • Average time to hatching
    14 days
    AnAge
  • Range fledging age
    15.0 to 17.0 days
  • Average age at sexual or reproductive maturity (female)
    1.0 years
  • Average age at sexual or reproductive maturity (male)
    1.0 years

The young are completely helpless and depend on their parents, who both care for the young. They fledge after about 15 to 17 days and all leave the nest within a few hours of each other.

How long do they live?

The oldest House Wren has been known to live is 7 years. It is hard to keep track of the age of individual birds because they do not always return to the same spot every year.

How do they behave?

House Wrens mostly hop while on the ground and have a direct, steady flight only about 1 meter above the ground in open areas. House Wrens are most active during the day. They migrate yearly between breeding and wintering areas. They are very territorial and are usually found alone, in pairs, or in immediate family groups. Males take primary responsibility for defending the territory and will chase away intruders. They usually only have one mate, and both parents help to raise the young.

How do they communicate with each other?

House Wrens are widely known for their songs. While both sexes produce calls and songs, the males' songs are more complex. Altogether 130 different song types are known from House Wrens. Unmated males can sing for up to 10 minutes. Males with a mate are known to produce a "whispering song", where he sings without opening his bill to produce a very quiet song. This song type only occurs around the time of copulation. The purpose of the quiet song may be to not reveal the location of his fertile mate to other males. The female sings during the first days of pairing when she responds to her mate's song.

They will also communicate using body language. If a predator is approaching the male will crouch, droop his wings, erect his back feathers, and lower his fanned out tail.

What do they eat?

House wrens feed primarily on small, terrestrial insects. The independent young and adults consume mostly spiders, beetles, and bugs while the babies still in the nest (called nestlings) are fed mostly grasshoppers, crickets, and caterpillars. Adults will feed their young, and supplement their own diet, with sources of calcium such as mollusk shells.

  • Primary Diet
  • carnivore
    • eats non-insect arthropods

What eats them and how do they avoid being eaten?

Adults respond to predators by chasing and striking at the predators while giving a loud, harsh alarm call. Cats, rats, opossums, woodpeckers, foxes, owls, raccoons, squirrels, and various snakes are known predators of this species.

What roles do they have in the ecosystem?

House Wrens help to control several insect populations. They also supply an abundant food source for many different types of animals.

How do they interact with us?

House Wrens eat many insects that humans consider to be pests.

  • Ways that people benefit from these animals:
  • controls pest population

Are they endangered?

House Wrens are a very abundant species. They live in semi-forested areas, which is a common habitat type so conservation management is not necessary. However, House Wrens are protected under the U.S. Migratory Bird Act. These birds are quite tolerant of habitat change and nest disturbance, allowing them to live and reproduce successfully even in human populated areas.

Some more information...

There are roughly 30 different subspecies of House Wrens. These subspecies are divided into 5 groups: Northern House Wrens, Brown-throated Wrens, Southern House Wrens, Antillean House Wrens and Cozumel Wrens. Southern House Wrens have 20 of the subspecies in their category.

Brown-headed Cowbirds sometimes lay their eggs in House Wren nests. These birds act as a parasite to House Wrens but, because Brown-headed Cowbirds usually are too big to enter House Wren's cavity nests, this is a very rare occurrence.

 
University of Michigan Museum of ZoologyNational Science Foundation

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. "Troglodytes aedon" (On-line), Animal Diversity Web. Accessed June 27, 2017 at http://www.biokids.umich.edu/accounts/Troglodytes_aedon/

BioKIDS is sponsored in part by the Interagency Education Research Initiative. It is a partnership of the University of Michigan School of Education, University of Michigan Museum of Zoology, and the Detroit Public Schools. This material is based upon work supported by the National Science Foundation under Grant DRL-0628151.
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