It was a chilly March morning at Clifton Gorge, where we had moved up our April trip to see if we could find very early spring wildflowers. There were lots of early Hepatica and a few other species, but the big surprise was Louisiana Waterthrushes. Several were singing along the full-flowing and noisy Little Miami River, already jousting for territories that they would hold until July. We heard them long before we saw even one, and the loud songs echoed through the Gorge. The leaves were not fully out on the trees and these warblers were already on territory, a month or two ahead of most of their wood warbler brethren. It was yet another mind-blowing feature of these very unusual birds.
Waterthrushes really bend the rules of being a warbler. Their migration schedule is different – Louisiana’s arrive early and leave early, often flying south by the end of July. They also choose a bizarre habitat for a warbler – streamsides, where they chase down aquatic and stream-hatching insects. One of my birding mentors in Florida used to say they were “the warbler that thinks it’s a sandpiper.” They also sport a dull coloration for both males and females, looking like an undersized sparrow, with a plain brown back and a streaked white belly. No yellows or greens on these warblers.
Waterthrushes actually come in two flavors. We’ve focused on the Louisiana, the common breeding waterthrush of Ohio and most of the eastern deciduous forest, from northern Florida to southern Ontario (see this range map). They tend to like streamsides in hilly areas, like the Hocking Hills or the Mohican area. There is also the Northern Waterthrush, a bird that favors northwoods bogs from northern New England and upstate New York across Canada to British Columbia, with some populations extending down the Appalachians to Pennsylvania and Virginia (range map).
Here’s a nice composite video of Northern Waterthrushes in Maine:
The birds have subtle differences in plumage – the Louisiana has a clear, unstreaked throat and a white eye line that widens a bit towards the back of the head, while the Northern has a streaked throat and a yellow-white eye line that seems to narrow towards the back of the head. They both migrate to southern Mexico, Central America and northern South America, but have different wintering habitats: Louisianas winter on rivers and streams, while Northerns favor mangrove swamps.
For Louisiana Waterthrushes, living by streamsides has forced them to alter the warbler template in a lot of ways beyond those mentioned above. It has allowed them to arrive a lot earlier than other warblers because their insect food source isn’t tied directly to plants. They’ve also adopted a Spotted Sandpiper-like teetering to help them flush up insects from the ground or water’s edge, shown well in the next video:
They also have a loud, un-warbler-like song that helps them be heard above the noise of these streamside habitats. Listen to their songs in this video:
Perhaps unsurprisingly, they build their nests in a rocky crevice or eroded slope along the stream, presumably to make commuting with food easier. They also don’t usually defend a wide area, but patrol a length of stream instead.
Do all of these changes help waterthrushes in the face of human habitat modifications or climate change? So far, the answer looks like it might be yes. Both waterthrushes are some of the few warbler species whose populations have actually increased since the 1970s. Louisiana Waterthrushes have actually expanded their ranges in the past 50 years into upstate New York and central New England. Their streamside habitats are less likely to be erased like some woodland habitats, though deforestation and suburbanization probably take their toll. In fact, the original deforestation of the Appalachians back in the 1800s was probably a serious blow to these waterthrushes, and their population has rebounded as the hill areas have become reforested.
Where can you see these wild and weird warblers? Fortunately, you can find Louisianas commonly in Hocking Hills parks like Clear Creek or Conkle’s Hollow, but a few pairs also make their home in local Metro Parks around Columbus. Look and listen for them in the wooded ravines of Blendon Woods, Highbanks, and Battelle Darby Metro Parks. Actually, you’ll hear them long before you see them. Use the loud song to guide your search, and don’t be surprised if the singer is up in a tree instead of by the streamside. Waterthrushes have never met a rule they didn’t want to bend.