Carolina Wren

Appearance

Typically 12.5 to 14 cm with a 29 cm wingspan and a weight of about 18 to 23 g, it is a fairly large wren; among the United States species it is second largest after the Cactus Wren.

Among standard measurements, the wing chord is 5.4 to 6.4 cm, the tail is 4.5 to 5.6 cm, the culmen is 1.4 to 1.8 cm and the tarsus is 2 to 2.3 cm. The upperparts are rufous brown, and the underparts a strong orange-buff, usually unmarked but faintly barred on the flanks in the southwest of the range. The head has a striking pure white supercilium and a whitish throat. The race ''albinucha'' is duller brown above and has additional white streaking on the head.

It is easiest to confuse with the Bewick's Wren, a fairly close relative, which differs in being smaller but with a longer tail, grayer-brown above and whiter below. The Carolina and White-browed Wrens differ from the House Wren in being larger, with a decidedly longer bill and hind toe; their culmen has a notch behind the tip.

Habitat

The Carolina Wren is sensitive to cold weather. Since they do not migrate and stay in one territory the northern populations of Carolina wrens decrease markedly after severe winters. Because of this sensitivity to weather, gradually increasing temperatures over the last century may have been responsible for the northward range expansion seen in the mid-1900s.

Populations in Canada and the northern half of the US experience regular crashes following severe winters, but their high breeding productivity soon results in a return to higher numbers. These birds are generally permanent residents throughout their range and defend territory year round; some birds may wander north after the breeding season.

Reproduction

These birds prefer sites with dense undergrowth, either in mixed forests or in wooded suburban settings, in a natural or artificial cavity. The nest is a bulky, often domed structure, with a small hole towards the top. Nests of the more domestically-inclined wrens have been reported in a great variety of nooks and crannies in, about, or under buildings of various kinds, under bridges, or in holes in any structure such as a porch, fence-post, flowerpot, tree, house or barn. Almost any kind of receptacle may offer an acceptable nesting site. Pairs may mate for life.

Females typically lay between four to six eggs up to three times per year . Eggs are oval, grayish-white and sprinkled with reddish-brown spots. Incubation is performed by the female only and lasts anywhere from 12–14 days, with the first young leaving the nest 12–14 days after hatching. Chicks hatch bald and blind, and depend upon parents until fledging. Both the male and female feed the young. They only brood for a short period of time after hatching, leaving the young in a warm, down-lined nest while adults search for food. If conditions are right, the same nest may be used more than once.

Food

They eat insects, found in leaf litter or on tree trunks; they may also eat small lizards or tree frogs. In winter, they occasionally eat seeds, berries, and other small fruits.