Wrens have evolved to take advantage of virtually all types of habitat in their geographic range. However, certain genera tend to specialize in particular kinds of habitat. The genus Cistothorus, the marsh wrens, is predominantly found in marsh-edge vegetation such as reeds and cattails, though one species also occurs in wet high-altitude Andean grassland. The most arid areas are occupied by the large wrens of the genus Campy-lorhynchus, though again, some members occur in lowland tropical forest. The largest genus is Thryothorus, the majority of whose species live in dense forest or forest-edge, often at considerable elevations. Some wrens have become very specialized; the canyon wren of western North America is essentially confined to canyons, more rarely sea-cliffs. The two members of the genus Hylorchilus occur exclusively in tall forest on limestone karst outcrops. The majority of species in the tropics are found in forest. The highly terrestrial members of the genus Microcerculus are found in wet lowland forest, and the genus Cinnycerthia occurs in wet montane forest. Wrens do not usually adapt well to gross habitat modification, but a few species have developed a reasonable coexistence with humans. Northern and southern house wrens are abundant in abandoned farmland, clearings, and well-treed suburbs, and undoubtedly have expanded their range to take advantage of forest clearing. The Bewick's wren expanded greatly into eastern North America as agriculture moved westward in the nineteenth century. The winter or Eurasian wren occupies a range of habitats. In North America, it tends to be restricted to cold, wet northern forest. However, after it crossed the Bering Strait into three new continents, it was without competition from any other wrens, and it expanded into a great variety of habitats, from low brush in remote oceanic islands to high-altitude bushland in Central Asia, cedar forest in North Africa, and suburban gardens in England.

A house wren (Troglodytes aedon) in flight in Pennsylvania. (Photo by Joe McDonald. Bruce Coleman Inc. Reproduced by permission.)

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