Northern House Wren Life History

Habitat

Northern House Wrens have a large geographic range, and they live in many habitats, so long as they feature trees, shrubs, and tangles interspersed with clearings. Examples range from eastern deciduous forests and southern swamps to western conifer forests and aspen groves as high as 10,000 feet elevation. Because they're cavity nesters, Northern House Wrens thrive around buildings, yards, farms, and other human habitations with their many nooks and crannies.

Food

Northern House Wrens eat 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. They also eat snail shells, probably for the calcium they contain and to provide grit for digestion.

Nesting

Nest Placement

Northern 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.

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.

Nesting Facts

Behavior

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 Northern 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. Northern 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

Northern House Wren populations have experienced some regional declines, but generally populations have been stable and slightly increased between 1966 and 2021, according to the North American Breeding Bird Survey. Before the taxonomic split in 2024, Partners in Flight estimated a global breeding population of 190 million for House Wren (which included Northern House Wren, Southern House Wren, and Cozumel, Kalinago, St. Lucia, St. Vincent, and Grenada Wrens) and rated the species a 5 out of 20 on the Continental Concern Score, indicating a species of low conservation concern.

Credits

Chesser, R. T., S. M. Billerman, K. J. Burns, C. Cicero, J. L. Dunn, B. E. Hernández-Baños, R. A. Jiménez, O. Johnson, A. W. Kratter, N. A. Mason, P. C. Rasmussen, and J. V. Remsen, Jr. (2024). Sixty-fifth Supplement to the American Ornithological Society’s Check-list of North American Birds. Ornithology 141:1–20.

Ehrlich, P. R., D. S. Dobkin, and D. Wheye (1988). The Birder's Handbook. A Field Guide to the Natural History of North American Birds, Including All Species That Regularly Breed North of Mexico. Simon and Schuster Inc., New York, NY, USA.

Johnson, L. S. (2014). House Wren (Troglodytes aedon), version 2.0. In The Birds of North America (A. F. Poole, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA.

Lutmerding, J. A. and A. S. Love. (2020). Longevity records of North American birds. Version 2020. Patuxent Wildlife Research Center, Bird Banding Laboratory 2020.

Partners in Flight. (2020). Avian Conservation Assessment Database, version 2020.

Partners in Flight (2023). Avian Conservation Assessment Database, version 2023.

Sauer, J. R., D. K. Niven, J. E. Hines, D. J. Ziolkowski Jr., K. L. Pardieck, J. E. Fallon, and W. A. Link (2019). The North American Breeding Bird Survey, Results and Analysis 1966–2019. Version 2.07.2019. USGS Patuxent Wildlife Research Center, Laurel, MD, USA.

Sauer, J.R., Link, W.A., and Hines, J.E., 2022, The North American Breeding Bird Survey, Analysis Results 1966 - 2021: U.S. Geological Survey data release, https://doi.org/10.5066/P9SC7T11.

Sibley, D. A. (2014). The Sibley Guide to Birds, second edition. Alfred A. Knopf, New York, NY, USA.

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