While I find this species to be a handsome animal, it probably would rank low among eastern North America's 38 breeding warbler species in the looks department, to most people. There's a lot of competition, including gorgeous lookers such as Common Yellowthroat, Magnolia Warbler, Prairie Warbler and many others. But who cares? All of that is superficial. To me, the Swainson's Warbler - a species I have come to know well over the past few decades - is fascinating on several fronts.
One is its rarity. Swainson's Warbler is the third rarest breeding warbler in eastern North America, with a total population estimate of about 140,000 birds. The Kirtland's Warbler eclipses it in rarity, by a longshot. A census conducted in 2025 produced only 1,489 pairs, or 2,978 individuals. Rarer yet - WAY rarer - is the Bachman's Warbler. Most people consider it extinct, including me, and the last documented, acceptable sighting was in 1961 in South Carolina.
Undated photo, photographer unknown (at least to me)
The above photo shows a man on horseback in front of a stand of giant cane (Arundinaria gigantea). It was obviously taken long ago. This enormous grass, the bamboo of eastern North America, forms extensive stands known as canebrakes. This was the primary habitat of Swainson's Warbler. I say "was" because humans have destroyed nearly all of the canebrakes, which used to occur commonly along streams and river across much of the eastern U.S. That undoubtedly included the north side of the Ohio River and its immediate tributaries.
Map courtesy BONAP (Biota of North America Program)
The light green counties on the above map show where giant cane occurs, or mostly, USED to occur. As noted, most of the large canebrakes no longer exist. These records are based on plant specimens, most of them probably very old.
Map courtesy of Birds of the World (Cornell Lab of Ornithology)
This is the range map of the protagonist of this post, the Swainson's Warbler. The pinkish areas represent the breeding range. You'll notice a lot of overlap with the giant cane map.
Although there's no way to prove it, I would bet that the north side of the Ohio River, in Ohio, hosted breeding Swainson's Warblers. There certainly must have been large canebrakes. There are numerous other plant species that also reach their northern terminuses on the Ohio side of the Ohio River.
One of the great tragedies was the shockingly fast and sweeping destruction of canebrakes. Rivers were the highways for settlers invading the Ohio Country and elsewhere in the interior, and the cane would have been quite easy to destroy with fire or simple tools. Canebrake land would have made for very fertile croplands and potential town sites. Anyway, it was pretty much gone before anyone had a chance to document the extent of the canebrakes.
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As always, click the photo to enlarge
Nonetheless, scraps and fragments of canebrakes persist. Including the one above. Most of the understory in this shot is cane, growing along a small stream in Shawnee State Forest in Scioto County, Ohio. I was standing approximately in the middle of the stand when I made this image on May 7, 2025.
In 2024, a singing Swainson's Warbler was found here, and it stayed for quite a while. The following year, 2025, it or another returned and summered, but apparently was without a mate.
While I had heard the 2025 bird, I saw no evidence of a mate or breeding. But I did discover something very interesting, that might account for the birds' interest in this site. On May 7, I visited this location, but came in the long way, from the heart of the forest to the north. As I neared the location, windows rolled down and listening intently, I noticed cane thickets through the woods, along the stream. Come leafout of trees and shrubs, the cane is completely concealed but leaves were still undeveloped by the time of my visit.
I bushwhacked back to the cane and saw that the stand was fairly extensive, although I still need to go back in there and get accurate measurements of its extent. It is by far the largest canebrake I have seen, and indeed, the only one I have seen in Ohio.
So, I don't think it is a coincidence that Swainson's Warblers are smitten with this site. And I wonder if and how long they may have been summering here before some sharp birders discovered them in 2024. Also, on my visit this spring, I found four Swainson's Warblers! I watched what was undoubtedly a pair: a singing male closely hanging with another, even together on the same branch. This species is monomorphic and as far as I know, cannot be sexed visually. Walking down the road aways produced two other singing males. I have no idea whether they also had mates.
I imagine finding a Swainson's Warbler nest is not easy, even though they are often within 4-5 feet of the ground, although they've been found as high as 12 feet. Their nest is the largest of any wood warbler, but its exterior is covered with dead leaves, so the nest can look much like an old clump of leaves or flood debris. The female does all the construction, but the male is often close at hand. Sometimes the nest is woven into the cane, or it might be placed in dense shrubby growth nearby.
While the first Swainson's Warbler in Ohio was discovered in 1947 in Lawrence County, and there have been at least eight territorial singing males in or near Ohio River counties since (not counting the birds described in this post), and at least two of those older reports mention two birds were present, breeding has never been documented in the state.
As there are most definitely at least one pair at the Shawnee site, I would think they would attempt nesting. But given their rarity, it probably wouldn't be a good idea for lots of people to traipse about the site seeking a nest. Hopefully a careful, targeted search can be undertaken by one or two stealthy, knowledgeable people. It would be most useful to know for sure if they are breeding, not only for potential management considerations, but to document the first nesting of this species on the north side of the Ohio River.
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