Louisiana Waterthrush

The Louisiana waterthrush, Parkesia motacilla, is a New World warbler of modest plumage, yet striking in its own right. It is characterized by a plain brown back and a white belly adorned with bold black streaks. The flanks and undertail are tinged with a warm buff color, and a pronounced white supercilium flares above its eye. The bird's legs are a vivid pink, adding a dash of unexpected color to its otherwise earthy tones.

Identification Tips

When attempting to distinguish the Louisiana waterthrush from its close relative, the northern waterthrush, look for the buff flanks and undertail, a feature unique to the Louisiana. Additionally, the Louisiana waterthrush has a longer supercilium and brighter pink legs. Juveniles may be identified by their buff, rather than white, underparts. The species is the largest of the wood warblers, measuring 14–17 cm in length with a wingspan of 21–25.4 cm.

Habitat

The Louisiana waterthrush shows a strong preference for wet woodlands adjacent to running water. It is within these riparian corridors that the bird thrives, utilizing the dense vegetation along the water's edge for nesting and foraging.

Distribution

Breeding in eastern North America, the Louisiana waterthrush's range extends from southernmost Canada through the eastern United States, avoiding Florida and the coast. Come winter, it migrates to Central America and the West Indies. It is a rare visitor to the western United States.

Behaviour

Upon arrival at its breeding grounds, the male Louisiana waterthrush begins to sing, a behavior not observed on its wintering grounds. The male's song is a musical cascade of descending notes followed by a warble, reminiscent of the flowing streams it inhabits. Both the Louisiana and the closely related northern waterthrush exhibit a characteristic tail bobbing behavior.

Song & Calls

The male's song is a melodious series of descending notes followed by a warble, with the initial notes often mirroring the downward flow of its preferred stream habitats. The call is a sharp "chink," alerting others of its presence.

Breeding

The Louisiana waterthrush selects dense vegetation near water for nesting, often in a rock crevice, mud bank, or among tree roots. The nest, constructed by both parents, is a cup of wet leaves, pine needles, grass, and twigs. The female incubates 4–6 eggs for about 12-13 days, and after hatching, both parents feed the young for an additional 4 weeks.

Similar Species

The northern waterthrush is the species most commonly confused with the Louisiana waterthrush. The northern has white flanks and undertail, a striped throat, a smaller bill, a shorter supercilium, and duller pink legs.

Diet and Feeding

The Louisiana waterthrush is unique among passerines for its foraging habits in running water, where it primarily consumes aquatic insects, molluscs, and crustaceans. It may also feed on ground insects and occasionally captures flying insects in midair.

Conservation Status

The Louisiana waterthrush is considered of Least Concern, but its populations have declined due to habitat loss from stream clearing, pollution, and the creation of reservoirs. Forest fragmentation, timber harvesting, agriculture, urban development, and gas drilling pose additional threats to its habitat. The species is sensitive to changes in habitat quality and quantity, with Canadian populations particularly at risk from reduced insect prey and water supply issues.