Lincoln’s sparrow: Sweet notes from a secretive bird

By Joan Collins 

The Lincoln’s sparrow, a small, secretive bird with a lovely voice, is one of two boreal bird species in the Adirondacks that nest primarily in bogs. (The other being the palm warbler.)

On a trip to Quebec in 1833, John James Audubon gushed about the “sweet notes” of a new species he had discovered that surpassed any American finch species’ song. Thomas Lincoln, one of his young companions on the trip, shot one of the birds, acquiring the first specimen. Before the advent of conservation, the early ornithologists carried guns, not binoculars. Audubon subsequently named the bird “Lincoln’s finch” in his honor.

Its breeding grounds span from Alaska across Canada to Newfoundland, and south into western portions of the U.S. and northern regions of the upper Midwest and northeastern states bordering Canada. The Adirondack region is the southern edge of its breeding range. The winter range includes the western and southern U.S, Mexico and Central America. It nests primarily in bogs of the Adirondacks, but I have occasionally found them nesting in marsh edges and wet fields.

As with many other species in its family, Lincoln’s sparrow has dark-streaked pale brown upperparts, allowing it to blend into its ground-dwelling habitat. It is pale below with a buffy breast that is marked with delicate black streaks. The edges of its wings and tail feathers are reddish. It has a distinctive gray supercilium and a narrow, buffy eye-ring.

They nest in a depression of moss on the ground with dense shrub cover often found at the base of small black spruce or tamarack trees scattered in the bogs. Their clutch size averages four eggs. Females stay hidden and scoot like mice in vegetation tunnels leading to their nests. Males sing from open perches in shrubs or trees.

And what a voice! I find the Lincoln’s sparrow’s song to be captivating. It has been described as “rich, warbling and wrenlike.” Possibly unique among new world sparrows, its song has polyphonic phrases. It uses both sides of its syrinx, a unique voice box buried deep within a bird’s chest, to produce two different sounds at once. To stand next to a singing Lincoln’s sparrow is a musical thrill for your ears.

Insects, spiders and seeds make up most of their diet on the breeding grounds. In winter, they mostly eat small seeds.

Lincoln’s sparrows face several threats, including loss of shrubby habitat on their migration routes and winter grounds due to livestock overgrazing; window collisions; predation at nests; and they are particularly vulnerable to climate change. Declines are already showing up in the eastern part of their range in North America where they face extirpation from rising temperatures. Global warming will eliminate 75% of their breeding habitat if the predicted increase in the Earth’s temperature of 3 degrees Celsius by the end of the century happens. That would eliminate them from the U.S. and most of Canada.

In the current New York Breeding Bird Atlas III project, Lincoln’s sparrow is a priority species with a worrisome decline in breeding confirmations. I have been observing a steep drop in numbers for a few years, but particularly this year. While you can still find them in most Adirondack bogs, the numbers are way down, and often absent in smaller pockets of boggy habitat.

During the Adirondack Birding Festival, I lead an annual trip to Massawepie Mire, New York’s largest bog, where we walk out on an impressive boardwalk into a vast section of open peatland. Each year, we hear lots of Lincoln’s sparrows singing around us while on the boardwalk platform with many great views through my scope and participants’ binoculars.

But this year, only one distant bird sang, too far away to see. It was heartbreaking. I often assume the effects of climate change will be linear, but find they are mostly abrupt.

I hope readers delight in the “sweet notes” of the Lincoln’s sparrow’s song before they disappear from our Adirondack landscape.