Colored Like the Sky

Of A Feather
By Bill Chaisson
Two weeks ago I was up at the Langenau Forest in Wilmot. It had been a good day for warblers, and then I heard a song I initially took for a parula warbler, but it didn’t have the so-called sneeze at the end. I thought it was a cerulean warbler (Setophaga cerulea) and tried to locate it with my binoculars, but had no luck. David Sibley renders the song as tzeedl tzeedl tzeedl ti ti ti tzeeeee and he finds it more musical than the parula’s song.

Back home, I reported on NH Birds that I had heard a cerulean warbler, but had not seen it. I got a quick response from another member who alerted me to the fact that the black-throated blue warbler (Setophaga caerulescens) has a song quite similar to that of the cerulean. He forwarded two recordings made by Sibley—one of each species—and indeed they were almost impossible to tell apart.

A couple of days later I returned to Langenau to try to lay eyes on this bird. I went back to the same spot on the loop trail, and I did hear it again, but once again could not find it. It was up very high in the canopy, which is a little unusual for a black-throated blue and quite normal for cerulean. The black-throated blue warbler is very common at Langenau, and I heard several more singing their more characteristic song as I made my way around the loop.

Then I reached the edge of a big timber cut that affords a good view of Pleasant Lake and I heard the “cerulean-type” song again, at the edge of the forest. My heart sank. What were the odds that there were two singing males of this species in one Forest Society property? Pretty long, actually. And this was good black-throated blue habitat. The Sibley recording had been made in western Massachusetts; the song variant has evidently made its way north in S. caerulescens culture. As someone who was born in western Mass. and now lives up here too, I could not begrudge him.

Sibley’s range map for cerulean warbler (pronounced seh-RU-lee-en, I only recently learned) is more expansive than the one at allaboutbirds.org. While Sibley shows it to range into western Massachusetts with isolated sightings in New Hampshire and Maine, allaboutbirds.org shows it reaching northeast only to the Catskills in New York. While most wood warblers are denizens of the northern forests—both coniferous and deciduous—the cerulean’s historical stronghold is Ohio and Mississippi river drainages. This isn’t unique; the Kentucky warbler (Opornis formosus) has a similar range, as does the hooded warbler (Setophaga citrina) and a few others. But the range and the numbers of S. caerulea are shrinking, and it is not entirely clear why.

In 2010 the cerulean warbler was featured on the cover and in the plot of Jonathan Franzen’s novel Freedom. One of the protagonists works for a nonprofit that is working to create a preserve for the bird in West Virginia, where prime breeding habitat is threatened by a coal strip mine. In 2011 Katie Fallon wrote Cerulean Blues: A Personal Search for a Vanishing Songbird, a memoir about the author’s unhappiness with the decline of the species, but also a meditation on surviving the 2007 mass shooting at Virginia Tech, where she was teaching.

Why has the bird attracted this kind of attention (and more)? Because since 1966, the Breeding Bird Survey has documented a 3% loss of population each year. That is, there are 80% fewer now than in the mid 1960s. Hence my excitement when I heard what I thought was the song of this bird. The Birds of New Hampshire (Keith and Fox, 2013) describes its status here: “A rare southern warbler, it has become nearly an annual spring visitor and a rare breeder since the mid-1980s. A species of Special Concern in New Hampshire.” The observations somewhat near Wilmot include one at Mascoma Dam in Lebanon in 1995, Canaan (1980), New London (1988), and Enfield (1995). Keith and Fox regard it as “extending its range in very small numbers into the Northeast in recent decades, but declining in other parts of its historical range.”

According to allaboutbirds.org: “Cerulean Warblers breed in large tracts of older deciduous forests with tall trees. In the Appalachian Mountains many warblers nest on north and east-facing slopes and seem to gravitate toward gaps or openings in the canopy. They tend to use white oak, cucumber magnolia, bitternut hickory, and sugar maple for nesting and foraging, typically avoiding red oak and red maple.” This is an unusually specific description of habitat use, even for a wood warbler. The species is famous for remaining very high in the canopy and for needing unfragmented forest. That is, zoning ordinances that legislate large lots (5 acres and larger), resulting in clearings filled with houses and lawns littered through the mature forest, is very bad for this bird (among other species).

The males and females are so different looking that they were originally classified as different species. The males are sky-blue above and white below with blue streaks on the sides and flecks of white on the wings, tail and back. The female is bluish-green above, has a white stripe over the eye, two white wing bars, and is yellowish below. Both are tiny, barely over 4 inches long with short thin bills.

The cerulean warblers spend their winters in the Andes, often in shade-grown coffee plantations, which has led to their being a poster child for that type of bean and the ecological benefits that go with it. But clearances for “normal” coffee plantations continue and the numbers of the cerulean warbler continue to decline.

Bill Chaisson has been birdwatching for over 50 years. He lives and works in Wilmot. Contact him at [email protected].