Wrens: Troglodytidae

Wrens are often known to be secretive in their habits, though this characteristic does not include all members of the family. Some species, such as the cactus wrens, are very much the opposite of secretive—they are noisy birds who make their presence known. Still, most wrens do like to live quiet lives and spend their days in the lower levels of dense undergrowth. They disappear when they notice the least noise or activity that is outside of their own. The nightingale wren is a prime example of this sort of disappearance. Because of this, the nightingale wren is also very hard to observe.

The wrens' vocalizations are what make them noticeable. They sing very loudly, usually way out of proportion for their size. Some species sing not simply in spring or summer but throughout the year. Wrens can have as few as three songs to as many as 219, which is the number of songs recorded from the western marsh wren. Vocalization is used as territorial protection and defense during and outside of breeding seasons.

Wrens have three breeding habits that are unique. They build multiple nests, have multiple partners, and have cooperative nesting, meaning other birds help care for the nest of a breeding pair. Egg destruction of both their own and other species' eggs is also common. Observers have suggested that this could be a way of reducing competition for food sources. In fact, the population decline for some wrens, such as Bewick's wren in eastern North America, has been directly linked to the rise of population in the house wren, due probably to its habit of attacking nests.

The nests that wrens build for breeding are sturdier than those built just for roosting. Wrens like to have a quick getaway when disturbances are nearby, and this led observers to believe that the flimsy roosting nests makes that quick getaway easier. Other species, like the cactus wrens, roost in their nests year-round. Most of the nests are domed with side entrances. Some species, like the northern house wren, do not build nests with a roof over them. Also, many other species build beautiful and elaborate nests, sometimes with two chambers. In the case of the song wren, the opposite is true—their nests are very messy.

North American wrens lay three to ten eggs at a time. The eggs are various colors, with some white to cream, tan, or pink, and often having a brownish mottling on them that can be very pale to very bold in color. The female of the smaller species incubates the eggs (warms them for hatching) for twelve to fifteen days; in larger species, the incubation might average up to sixteen days. The young are hatched helpless, blind, and naked, and are fed by both parents until they become fledglings (grow their flight feathers). This occurs when they are ten to seventeen days old in the smaller species, and an average of twenty-one days in the larger. After fledging, the parents continue to feed the young for about two weeks, unless the female begins produce another group of young. In that case it is usually the male that takes the responsibility for feeding. In many of the species, the young continue to return to the breeding nest to roost for an extended period of time. While some species breed at one year of age, others continue to stay with their parents for years and help raise their siblings. This is called cooperative breeding.