The Carolina wren (Thryothorus ludovicianus) is a common species of wren that is a resident in the eastern half of the United States of America, the extreme south of Ontario, Canada, and the extreme northeast of Mexico. Severe winters restrict the northern limits of their range while favorable weather conditions lead to a northward extension of their breeding range. Their preferred habitat is in dense cover in forests, farm edges and suburban areas. This wren is the state bird of South Carolina.
There are seven recognized subspecies across the range of these wrens and they differ slightly in song and appearance. The birds are generally inconspicuous, avoiding the open for extended periods of time. When out in the open, they investigate their surroundings and are rarely stationary. After finding a mate, pairs maintain a territory and stay together for several years. Both sexes give out alarm calls, but only males sing to advertize territory. Carolina wrens raise multiple broods during the summer breeding season, but can fall victim to brood parasitism by brown-headed cowbirds, among other species. Some populations have been affected by mercury contamination. Source: Wikipedia