Bird of the Week # 35
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. Carolina wrens sing year round and at any point during the daytime, with the exception of performing during the most harsh weather conditions. The birds are also the only species in the family Certhiidae that neither sings in duet nor has their song control regions affect repertoire size. Males alone sing, and have a repertoire of at least twenty different phrase patterns and on average, thirty two. One of these patterns is repeated for several minutes, and although the male’s song can be repeated up to twelve times, the general number of songs range from three to five times in repetition. While singing, the tail of the birds is pointed downward. Males are capable of increasing their repertoire through song learning, but due to their sedentary nature and territorial defense habits, the song learning must occur within the first three months of life. Geographic barriers affect song repertoire size from male wrens, as one study indicated that distances separated as close as 3 kilometres (1.9 mi) by water barriers can have the same effect as that of a distance of 145 kilometres (90 mi) in the mainland with no barriers.
Female Carolina wrens possess song control regions that would appear to make them capable of singing with repertoires like the male. Due to vocalizations that they occasionally make with the male, it has been suggested that song perception plays a role and is of behavioral relevance. Different subspecies have variations in songs and calls, such as miamensis having a more rapid song that contains more notes than the races that are further north. Their songs can be confused with the Kentucky warbler. The song patterns are similar, but the warbler’s songs are described as richer, with more ringing and a hurried pace. Other bird species with songs described as akin to the wren are the flicker, Baltimore oriole, grey catbird, and more specifically the peto, peto, peto call of the tufted titmouse and the whistle of the northern cardinal. Occasionally, the wrens mimic other species; in Pennsylvania this trait has caused the bird to be also known as the ‘mocking wren.
© HJ Ruiz – Avian101