Northern Waterthrush

The Northern Waterthrush is a large and brownish wood warbler, not a thrush, rarely seen far from water in the forests of North America. It is often shy and hard to approach and spends most of its time walking on the ground. Ornithologist E.H.Forbush’s statement over a half century ago still applies: “It is a large wood warbler disguised as a thrush and exhibiting an extreme fondness for water.” It has a wide distribution from the northeastern U.S., Canada, including central and northern B.C., Montana and Alaska. It winters in Mexico, northern South America and the West Indies.

Adult Male (spring/summer)

Generally dark brown above (varying in shade from cold gray-brown to warmer olive-brown) and whitish to sulphur yellow below. Throat, breast and sides are streaked in black and these streaks are sharply defined. Wings and tail are unmarked and dark brown. White to sulphur yellow supercilium is of even width, attenuated behind the eye. Leg colour varies but are usually light brownish.

Adult Female (spring/summer)

Males and females are identical in plumage but males are slightly larger in size. There is no significant seasonal variation.

Juvenile

Wings and tail as in adults but median and greater wing-coverts tipped with buff forming two narrow bands across wing; superciliary stripe less distinct than adult. Streaking much less sharply defined than in adults.

General:

This is a rather heavy-bodied, short-tailed, large warbler. The bill is fairly long and heavy, with a slightly decurved culmen. Length: 14-17 cm. Wing: 24cm. Weight: 18 g.

Behaviour:

The Northern Waterthrush combines a distinctive walking gait with bobbing of its tail and rear portion of its body. It will bob its tail almost continually in an up-and-down motion. It spends most of its time walking on the ground, although it will walk along tree limbs, some of which may be at a sharply sloping angle. It will continue to bob when flushed up onto a limb.
Their flight is swift and low.

Waterthrushes forage deliberately on the ground where there is damp leaf litter or shallow water, turning over leaves with the bill, gleaning invertebrate prey form the undersides of leaves or the ground under them.

Habitat:

Swampy or wet woods, wooded stream sides, lake shores and wooded pond edges, willow thickets and along slow moving rivers.

Information:

Singing birds will perch well above the ground on horizontal limbs, and even from treetops in stunted forests in the northern most parts of their breeding range.
Nests are located on or near the ground, often among the root system of a fallen tree, at the base of a standing tree, or set into a stream bank. The nest is a cup composed of stems, pine needles, and leaves and lined with moss stalks, rootlets and fibers. There are 4 to 5 off white eggs, marked with browns and purplish-gray.

Similar species:

Hermit Thrush, Louisiana Waterthrush, Ovenbird.

Conservation Status:

In ranking of Neotropical migrants for conservation priorities on a scale of 1 to 8, the Northern Waterthrush ranks number 8, based on its wide breeding and wintering ranges. Listed as Least Concern.

Capture Rates:

A rare transient to Colony Farm, the Northern Waterthrush is a breeding bird of northern interior forests. They generally frequent wooded areas that include water and are therefore not readily seen directly in the banding area. Capture rates concentrated in August and September reflect dispersal of these long distance migrants to their wintering grounds.

Molt Summary:

PF: HY partial (Jun-Sep); PB: AHY complete (Jun-Aug); PA limited (Oct-Apr).
PBs occur on the summer grounds.
Preformative molt usually includes all med and gr covs, but not the greater alula, terts, or rects.
PA: limited to feathers of the body and involve continuous, limited replacement on the winter grounds.

HY birds like this NOWA in August show narrow, rusty tips to the tertials (red arrows). Notice also the narrow, tapered outer primary coverts with faint rusty tipping.

The narrow, rusty tips to the tertials are very obvious in the super-macro photo below.