Louisiana Waterthrush (Seiurus motacilla)

Distribution

Breeding: Eastern United States, from the southern Great Lakes region (including southern Ontario and perhaps rarely in southwestern Quebec) to southern New England; from eastern Texas across the Gulf states to northern Florida.

Winter: Ranges from Central Mexico, although generally absent from Yucatan peninsula, through Central America into northern South America. Also winters in southern Florida, rarely in southern Arizona, the Bahamas, and throughout the West Indies.

Breeding habitat

Mature deciduous or mixed forests with moderate to sparse undergrowth, near rapid flowing streams. It is therefore often found in hilly terrain or in ravines; occasionally in mixed floodplain and swamp forests in flatter terrain. The key component of this species’ habitat is clear flowing water.

Conservation status

This species is of high conservation importance, because of its relatively small breeding range, low overall density, and dependence on clear forest streams both on its breeding and tropical wintering grounds. Populations of this warbler appear to be stable, although they are difficult to monitor accurately. Precise habitat requirements, especially the characteristics of forest patches surrounding their streamside territories, are poorly known. Effects of forest fragmentation and silvicultural and mining practices also are important to understand when planning for this species’ long-term conservation.

Description

Male: A large, heavy-bodied warbler with a short tail and long, heavy bill. Upperparts, including the wings and tail, are dark brown, sometimes with a slight olive tint. Coloration of the underparts consists of dark spotting on a white background with pinkish buff on the flanks. The throat is white and unmarked, a white eyebrow that widens behind the eye is perhaps the most prominent feature. Relatively long legs and feet pink.

Female: Same as adult male.

Juvenile: Dark brown above, rusty or buffy wing bars. Dull, whitish-buff with olive-brown streaking on the buffy throat, breast, and flanks. Sides of the head are mottledwith pale buff and olive-brown, a whitish eyebrow is bordered by a dark brown stripe behind the eye.

Vocalizations

Songs: The usual song consists of 2–5 loud, clear, whistled introductory notes that are a slurred upward, seeup seeup seeup, followed by a variable complex jumble of short, rapidly uttered phrases. A similar, but much longer and jumbled song is sometimes given.

Calls: Call note is a sharp, metallic chink, but not quite as metallic as the call note of Northern Waterthrush (distinguishable with practice). Both sexes utter a zizz call during courtship.

Foraging strategy

Forages primarily on the ground within the boundary of a stream channel, but occasionally searches trees during insect outbreaks. Primarily picks, or takes quick-jab-like strokes directly at food items, or at substrates such as herbaceous plants, leaf litter, soil, rocks, and moss. Other strategies include Leaf-pulls, where the bird grasps a dead leaf submerged in the water, pulls it upward, then flips it over to expose hidden prey; occasionally sallies upward for flying insects or hover-gleans prey from vegetation too high to be reached from a standing position.

Diet

Preferred prey are aquatic insects and invertebrates, also small to medium-sized flying insects. May sometimes eat small fish or small frogs.

Behavior and displays

• Wags entire back half of body and tail up and down while walking in a distinctive tail-pumping motion.

• Some birds roost on exposed roots under overhanging creek banks.

• Territorial neighbors engage in vigorous chases and counter-singing soon after arriving on the breeding grounds, males will continue singing while in pursuit. Neighboring males face each other and begin a Flapping Display by quickly raising wings above their back, then lowering them in a jerky manner.

Courtship

• Birds face each other on the ground and utter zizz call note, sometimes simultaneously. One bird, presumably male, may make sudden, short, erratic flights and land near female. If she flushes, male follows in pursuit until the birds return to same general area. If she does not flush, the female may walk slowly ahead of male with wings partly outstretched and vibrating with her head thrown upward past the vertical. She and the male then copulate.

Nesting

Nest Site: Ground dweller. Nests on the ground along stream banks, hidden in the underbrush or among the roots of fallen trees, in crevices or raised sites in tree roots, or in rock walls of ravines over water. Most cavities chosen are hemispherical in shape and approximately the same size as the nest or slightly larger. Cavities in which entire nest is protected above seem to be preferred.

Height: Usually in ground cavities along stream banks or under a fallen log, but occasionally nest is built in the root base of an upturned tree

Nest: A cup nest consisting of moss, leaves, twigs, inner bark is constructed within the cavity. While both male and female bring nest material, it’s uncertain whether male helps in nest construction.

Eggs: 4–6, usually 5, eggs are white to creamy-white. Speckles, spots, or blotches of reddish brown are usually concentrated at large end but sometimes scattered evenly over entire egg.

Incubation period: 14–16 days depending on the latitude, only by female. Male does not feed female, but accompanies her on foraging bouts.

Nestling period: The altricial young are fed by both parents, although the male appears to feed the nestlings more often. The nestlings quietly huddle together until an adult enters nest.

Fledgling period: Young leave the nest at ten days after hatching, lured by adult’s chip notes to protective shrubs or brush piles. Fledglings can fly six days after leaving nest, and begin feeding on their own at seven days.

Broods: Probably single-brooded, since adults often depart breeding territories by July.

Cowbird Parasitism: Frequent Brown-headed Cowbird host.

Notes

• Often the first warbler species to arrive on its breeding grounds; singing males arrive as far north as New York by early April.

• Pairs begin searching for a nest site within a day after pair formation. Male enters potential site, turns around several times while tugging at nearby leaves to drag them into cavity, and calls softly to nearby female. If she does not enter, male follows her farther up creek to explore other sites.