MAPS is a "constant-effort" mistnetting and banding program, created by the Institute for Bird Populations in 1989 to provide critical data for understanding the status (and changes in status) of North American breeding birds. At the present time there are nearly 500 banding stations, in 17 states, which are participating in the program.

Notes on Louisiana and Northern Waterthrushes

By Cin-Ty Lee

Illustrations by Andy Birch

Photos by Dave Rintoul/courtesy of MAPS & Christopher Wood

The Louisiana Waterthrush typically inhabits fast-flowing streams surrounded by forest. Unlike the Northern Waterthrush, which breeds over much of northern North America, the Louisiana Waterthrush breeds primarily in southeastern North America. While both waterthrushes are usually found near water, the Louisiana Waterthrush typically frequents fast-flowing wooded streams, whereas the Northern Waterthrush prefers bogs, swamps, and ponds. The Louisiana Waterthrush is one of the earliest spring and fall migrants, often passing through well-before the peak of warbler migration.

A number of features can be used to distinguish the two species. Louisiana is a slightly larger bird (sometimes described as chunky in comparison to Northern), the most noticeable feature being the slightly larger, heavier appearance of the bill. Louisiana is generally characterized by a broad white supercilium, which is often buffish in front of the eye and which broadens behind the eye. Northern’s supercilium tends to be uniform in color, most often with a yellowish wash. Louisiana tends to have white underparts, which contrast with buffy flanks. In contrast, the underparts of Northern tend to be uniformly washed with buff-yellow. While both species are streaked below, Northern nearly always has some streaking on the throat, whereas that of Louisiana is usually unstreaked and white. In addition, Northern appears to be more heavily streaked than Louisiana. Pictured here is a Louisiana Waterthrush banded in mid-July, 2000.

At first glance, this bird might be passed off as a Northern Waterthrush based on the narrow supercilium and the absence of a buffy wash on the flanks. However, the combination of white supercilium and underparts, unstreaked throat, sparse streaking on underparts, and a large, heavy bill point to Louisiana. The bright pink legs, if not an artifact of the photograph, are also consistent with Louisiana Waterthrush. The lack of a buffy wash on the flanks could be either an artifact of the photograph (possibly over-exposed due to use of a flash) or it may be within the range of variation of Louisiana.

There have been nine records of Northern Waterthrush in the Western Palearctic and one Louisiana on the Canary Islands in 1991 (see Birding World Vol.12 no.7)

Use this link to hear calls of both species

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