Louisiana Waterthrush

Our two species of waterthrushes, although warblers rather than thrushes, are at least closely tied to water. The Louisiana Waterthrush is the more southern species, and locally distributed in New Hampshire up to the southern edge of the White Mountains. It is closely tied to moving water, most typically a rapid stream in a hemlock-shaded gully, although sometimes it overlaps with the Northern Waterthrush where forest brooks meander into wooded wetlands. Males start arriving at their nesting streams in md-April, and hearing their loud ringing song over the sound of the rushing water is a sure sign that spring migration is here in earnest.

Louisiana Waterthrushes defend linear territories along their streams. Here they forage close to the water like a sandpiper, even picking insects out of shallow water or turning over submerged leaves to see what’s underneath them. Due to their reliance on aquatic insects, they are considered vulnerable to water pollution, and in fact occur at lower densities along contaminated streams such as those adjacent to mining operations in the Appalachians. This does not appear to have had significant impacts on populations however, which are stable or increasing over most of the species’ range.

The nest is built into a near-vertical surface close to the water, often a mossy bank or mass of upturned tree roots. Like most warblers the incubation and nestling periods are about two weeks, and once the young are independent they start to wander more widely. By late July birds can sometimes be found in unexpected locations like suburban yards, and soon after that they begin their southward migration. After early August Louisiana Waterthrush is actually quite unlikely in New Hampshire, and observers need to be careful in their identifications. Although quite similar in appearance to the Northern Waterthrush, Louisiana’s lack buffy tones to their underparts and have a narrower buffy eye-stripe.