Northern Waterthrush, by Barry Van Dusen
An artist who has created many of our covers, Barry Van Dusen lives in Princeton, Massachusetts, and is well known in the birding world. Barry has illustrated several nature books and pocket guides, and his articles and paintings have been featured in Birding, Bird Watcher’s Digest, and Yankee Magazine as well as Bird Observer. Barry’s interest in nature subjects began in 1982 with an association with the Massachusetts Audubon Society. He has been influenced by the work of European wildlife artists and has adopted their methodology of direct field sketching. Barry teaches workshops at various locations in Massachusetts. For more information, visit Barry’s website at <http://www.barryvandusen.com>.
The Northern Waterthrush (Parkesia noveboracensis) is a large, ground-dwelling warbler that constantly bobs its body and wags its tail and is rarely found far from water. The top of its head, back, and tail are dark brown. It has a narrow yellowish or white eye stripe, and it is yellowish to white below and densely streaked with brown or black, especially on the upper breast, and the throat is usually spotted. The sexes are similar in appearance. The Northern Waterthrush can be separated from its larger congener, the Louisiana Waterthrush (P. motacilla), by its smaller size, smaller and finer bill, the density of streaking on the upper breast, and the spotted throat. The legs of the Louisiana Waterthrush are a brighter pink. The Northern Waterthrush is easily separated from the Ovenbird (Seiurus aurocapilla), which lacks an eye stripe and does not persistently bob its body or tail.
The Northern Waterthrush’s breeding range extends from western Alaska in a broad band across Canada that includes the northern territories and the southern provinces from British Columbia through Ontario and Quebec to Newfoundland. It also includes the southern half of the Hudson Bay area. In the west, the range extends south into Idaho and western Montana. The range dips south again to encompass the Great Lakes and east to include New York and New England, extending south along the Appalachian Mountains to Virginia. Northern Waterthrushes winter from central Mexico throughout Central America, and in South America in Colombia, Venezuela, the Guianas to northern Brazil, northern Ecuador, and northeastern Peru. They also winter in Bermuda and in the Caribbean throughout the Bahamas and the Antilles and south to Trinidad and Tobago. The Northern Waterthrush is a long-distance nocturnal migrant, arriving on the breeding grounds from late April to mid-to-late May. In fall, migration often begins in mid-August and peaks in September. In Massachusetts, the Northern Waterthrush is considered a local and uncommon breeder, but a common migrant.
The Northern Waterthrush is usually monogamous, but occasionally may be polygamous. Pairs produce a single brood per year. The male’s primary song consists of a series of loud, clear, ringing, chirping notes that fall in pitch and become more closely spaced. The call has been described as sweet, sweet, sweet, swee, swee, swee, we, we, chew, chew, chew, chew. This primary call is used to defend territory and to attract a mate. The flight song, which is often given while the bird flies nearly vertically, begins on the ground with loud chirps, and in the air consists of hurried bits of the primary song. They also utter chink calls throughout the year. Northern Waterthrushes defend territories on breeding and wintering grounds. Defense involves uttering the chink call and a crouched approach to the intruder with head, back, and spread tail held in a straight line, wings quivering. They may also use a wing-droop display from a perch with tail cocked and flicking. Chasing and fighting with intruders is not uncommon. Once the female arrives on territory, the male may court by perching above her with wings vibrating, following her from perch to perch with wings buzzing, and circling above her.
Northern Waterthrushes nest in a wide variety of wooded wetlands, including forested swamps, bogs, lake and stream margins, and rhododendron, red maple, spruce, and cedar swamps and bogs. The female chooses the nest site, which is usually low in root systems of blown-down trees, the edges of clumps of ferns, or under the banks of lake or stream edges. The nest tends to be completely shaded and nearly invisible from above. The nest structure is a bowl of mostly moss and liverworts with a few leaves scattered about; an entrance to the bowl is constructed of leaves. The interior of the bowl is made of twigs and grass, pine needles, or rootlets and is often lined with mammal hair. Only the female develops a brood patch, and she alone incubates the usual clutch of five whitish eggs spotted or blotched with dark colors for the 12 days until hatching. The chicks are altricial—helpless with eyes closed —and usually have some black down. If disturbed, the female will leave the nest and move away with wings and tail spread, mouselike, drawing the intruder away. Both parents feed the nestlings, but only the female broods the young for the nine days until fledging. The young fly about a week after fledging. The brood is split between the parents who continue to feed the young for the four to five weeks until independence.
The diet of Northern Waterthrushes consists mostly of insects and insect larvae, spiders, beetles and, in some cases, snails or small clams. When foraging in water, they take aquatic insects and nymphs by wading and walking along branches or logs at the water’s edge. They forage on the ground, taking prey from litter, moss, and mud by pecking, gleaning, or probing the ground and associated surfaces. They also glean foliage and hover and hawk insects, flies, and other flying prey. On the wintering grounds, Northern Waterthrushes may forage in foliage up to the subcanopy level.
Breeding Northern Waterthrushes are not severely impacted by cowbird parasitism, but pesticides are a threat, as is habitat destruction, especially on the wintering grounds in the tropics. Broad distribution on breeding and wintering grounds, however, and Breeding Bird Survey reports that generally show increases in population suggest that this delightful warbler species has a secure future.