The Carolina wren is a large species of wren that is found in North America. There are seven recognized subspecies across the range of these wrens and they differ slightly in song and appearance. The males in this species are usually larger than their mates.
Carolina wrens breed in the eastern half of the United States of America, the extreme south of Ontario, Canada, and the extreme northeast of Mexico. These birds don't migrate, and will only disperse beyond their range after mild winters. They adapt to various habitats including oak hardwoods and mixed oak-pine woodlands, ash, and elmwoods, hickory-oak woodlands with a healthy amount of tangled undergrowth. The preferred habitats of Carolina wrens are riparian forest, brushy edges, swamps, overgrown farmland, and suburban yards with abundant thick shrubs and trees, and parks.
Carolina wrens are active during the day and spend the majority of their time on or near the ground searching for food, or in tangles of vegetation and vines. They also probe bark crevices on lower tree levels or pick up leaf-litter in order to search for prey. Carolina wrens are wary and are more often heard than seen. When on the ground, they move in jerky hops pillaging through various objects, whether man-made or natural. While moving abruptly, they pause momentarily for chattering or singing. When stationary, they move in twitched motions, jerking their breast around. They also sun- or sand-bathe. Other movements involve being capable of crawling like a creeper and hanging upside-down like a nuthatch. Their flights are generally of short duration, rapid, low-leveled, and wavelike. They are also capable of flying vertically from the base of a tree to the top in a single wing assisted bound. After finding a mate, pairs maintain their territory throughout the year, moving around and foraging together. Both males and females give out alarm calls, but only males sing to advertise territory. Males alone produce the 'cheer' call, which can sound indistinct. In southern regions of their range, the sound males use in alarm disputes is a ringing 'pink' or 'p'dink' sound. Females are the only ones that can perform the paired 'dit-dit' or chatter sounds often used in territorial disputes with predators. The chatter is used exclusively with territorial encounters with male song, and the song can either follow or overlap her mate's song.
Carolina wrens have a carnivorous (insectivorous) diet. They feed on invertebrates, such as beetles, true bugs, grasshoppers, katydids, spiders, ants, bees, and wasps. Small lizards and tree frogs also make up their diet. They may sometimes consume vegetable matter, such as fruit pulp and various seeds. In the northern portion of their range, Carolina wrens often visit bird feeders.
Carolina wrens are monogamous and will usually mate for life. They nest in cavities in trees, or in man-made structures such as bird-boxes, buildings, tin cans, mailboxes or unorthodox places such as pockets of hanging jackets in sheds or in a tractor in everyday use. Nests are usually placed 1-3 m (3.3-9.8 ft) from the ground and are rarely higher. These are arch-shaped structures with a side entrance and built of dried plants or strips of bark, as well as horsehair, string, wool, and snake sloughs. Males obtain nesting materials while the females remain at the site to construct the nest. Egg-laying dates and clutch size vary by region; in Texas, the time period is from late February to late August, in Iowa, it ranges from late April to June. The clutch size is generally 3 to 6 eggs but can reach as high as 7 in Texas. The eggs are creamy-white with brown or reddish-brown spots and are more heavily marked at the broad end. Incubation is done by the female and lasts 12-16 days. After the chicks hatch, they are fed exclusively on invertebrates and they fledge in 12-14 days. As many as three broods may be raised by a pair in a single breeding season. The chicks become independent 4 weeks after fledging and start to breed the first spring following their birth.
Carolina wrens are widespread throughout their native range and are not considered endangered at present. However, the populations of this species often fall victim to brood parasitism by Brown-headed cowbirds, among other species. Some populations suffer from harsh winters and mercury contamination.
According to Partners in Flight resource, the total breeding population size of the Carolina wren is 14 million individuals. Currently, this species is classified as Least Concern (LC) on the IUCN Red List and its numbers today are increasing.