The wren is a small, active songbird that belongs to the family Troglodytidae. There are around 80 species of wrens that can be found throughout the world, mostly residing in temperate climates. Wrens are known for their loud, complex songs and energetic behavior. They build dome-shaped nests out of twigs, grass, moss, and feathers. In terms of appearance, wrens have thin pointed bills, barred wings and tails, and brown, gray, or reddish-brown plumage.
In Pennsylvania, there are two species of wrens that are considered native – the House Wren and the Winter Wren. The question of whether or not these wrens are truly indigenous to Pennsylvania requires an examination of the historical record as well as analysis of their geographic distribution and habitat.
House Wren
The House Wren (Troglodytes aedon) is a small songbird that breeds throughout most of North America. It ranges from southern Canada through the United States, Mexico, and into Central America.
Physical Description
House Wrens have brown upperparts that are barred with darker brown, light gray underparts, and a pale eyebrow stripe. Their wings and tail are barred, and their bill is slender and slightly curved. House Wrens measure between 12-13 cm in length and weigh 10-12 g.
Habitat
As their name suggests, House Wrens are closely associated with human habitation. They thrive in areas where there are buildings, nest boxes, wooded parks and suburban gardens. House Wrens build their nests in tree cavities, walls, bird boxes or other artificial sites. They prefer lower elevation areas near water.
Breeding and Nesting
House Wrens breed throughout the central and eastern United States, southern Canada, and south to northern South America. The breeding range covers most of Pennsylvania. House Wrens typically arrive in Pennsylvania in April or May to establish breeding territories and construct nests. They have one brood per season, with clutches of 4-8 eggs laid in May-July. The female incubates the eggs for 12-16 days. Nestlings fledge about 16-18 days after hatching.
Diet
House Wrens are primarily insectivores, feeding on beetles, moths, caterpillars, flies, crickets, grasshoppers, spiders and other small invertebrates. They forage actively in vegetation, often hovering and hanging upside down while gleaning prey items. They also occasionally eat small fruits and berries.
Status in Pennsylvania
The House Wren is a fairly common summer resident and breeder in Pennsylvania. According to the Second Atlas of Breeding Birds in Pennsylvania, House Wrens were confirmed nesting in 51% of survey blocks statewide from 2004 to 2009. They nest throughout Pennsylvania but are more abundant in the southern and western parts of the state. House Wrens winter in the southern United States, Mexico and Central America.
Native Status
The House Wren likely inhabited Pennsylvania prior to European settlement, based on its broad distribution across eastern and central North America. The species favors human-altered landscapes and so it has likely expanded its numbers and range somewhat in Pennsylvania alongside development. However, most sources consider House Wrens native and indigenous rather than introduced in Pennsylvania and the Northeast.
Winter Wren
The Winter Wren (Troglodytes hiemalis) is a small North American songbird that breeds across Canada and the western and northeastern United States. It winters mostly along the Pacific and Gulf Coasts.
Physical Description
The Winter Wren is a tiny, round, short-tailed wren with reddish-brown upperparts and barred black and white underparts and flanks. It has a faint white eyebrow stripe and dark barring on the wings and tail. The bill is thin, straight and black. Winter Wrens measure only 9-10.5 cm long but have a very loud and complex song.
Habitat
During breeding season, Winter Wrens inhabit dense understory and thickets in moist coniferous or mixed forests, especially near streams, ponds or swampy areas. They nest on the ground concealed under fallen logs, brush piles or tree roots. In winter they reside in tangled woody debris along streams as well as in ravines and gullies.
Breeding and Nesting
Winter Wrens breed across Canada, the mountainous western United States, and the upper Midwest and Northeast regions including Pennsylvania. They usually arrive on their breeding grounds in April or May. Winter Wrens are monogamous and solitary nesters. The female builds a domed nest on the ground out of moss, leaves, ferns and bark strips, with a side entrance hole. She lays 5-10 eggs and incubates them alone for about 14 days. The young leave the nest at 14-18 days old.
Diet
Winter Wrens are insectivores, probing in crevices and under debris for small invertebrates including beetles, flies, mayflies, ants, caterpillars, spiders and millipedes. They occasionally eat seeds and berries.
Status in Pennsylvania
In Pennsylvania, the Winter Wren nests sparsely across the northern tier and higher elevation areas of the state. According to the Second Breeding Bird Atlas, confirmed nesting blocks were mainly in the Poconos, Allegheny Plateau, and northern Appalachian Mountains. The Winter Wren population has declined significantly in the last few decades.
Native Status
The Winter Wren is considered native to Pennsylvania. Historical records show it breeding in the state prior to the 20th century. Its habitat preferences for mature, undisturbed coniferous and mixed forests indicate that the Winter Wren evolved as part of Pennsylvania’s indigenous ecosystems.
Other Wren Species in Pennsylvania
In addition to the House Wren and Winter Wren, several other wren species can be found in Pennsylvania as rare visitors or non-breeding migrants:
Carolina Wren (Thryothorus ludovicianus)
The Carolina Wren is a year-round resident across the southeastern United States. In recent decades, it has expanded its range northward to breed in southeastern Pennsylvania, although the northernmost populations periodically die back in harsh winters.
Sedge Wren (Cistothorus platensis)
The Sedge Wren is an irregular breeder in Pennsylvania that nests in marshy grasslands and wet meadows. Breeding Bird Atlas data show scattered confirmed and possible nesting mainly in northwestern and northeastern parts of the state.
Marsh Wren (Cistothorus palustris)
The Marsh Wren is a locally distributed breeder in wetlands in the northern and western United States. In Pennsylvania, it is primarily a migrant and winter visitor but has nested sporadically in the northeastern counties.
Bewick’s Wren (Thryomanes bewickii)
Bewick’s Wren has declined dramatically in eastern North America. Today in Pennsylvania it is a very rare visitor, mostly in western areas. Historical records show former nesting around the turn of the 20th century.
Species | Breeding Status in PA |
---|---|
House Wren | Common summer resident |
Winter Wren | Uncommon summer resident in northern and high elevation areas |
Carolina Wren | Local breeder in southeastern counties |
Sedge Wren | Irregular breeder, mainly northwest and northeast |
Marsh Wren | Rare and local summer resident |
Bewick’s Wren | Extirpated as breeder, rare migrant |
Conclusion
In conclusion, the House Wren and Winter Wren are considered native species that inhabited Pennsylvania prior to European colonization. The House Wren thrives near human habitation and has likely expanded its population over time, while the Winter Wren relies on mature, undisturbed forests and has declined due to habitat loss. Other wren species occur in Pennsylvania as migrants, winter residents, or irregular nesters, but do not have stable, long-term breeding populations in the state. With appropriate habitat conservation, the House Wren and Winter Wren will hopefully continue as part of Pennsylvania’s native avifauna.