Henslow’s Sparrow, adult. May in Muskingum County, Ohio. Photo by Brian E. Small
When I was 18, I hitchhiked to Chicago, where another birdwatcher, Joel Greenberg (now famous author and naturalist), promised to show me a Henslow’s Sparrow. On a cool June morning, we visited the beautiful prairie of Goose Lake. Later, I wrote a poem about that day; it started like this:
A northern breeze chilled the blood, for little sun shone.
We plodded through the sticky mud of fields and swamps combining,
While all around us Henslow’s sparrows laughed and hid,
Avoiding birdwatchers with their craft and quirky children mocking…
I won’t bore you with the rest, but this fragment conveys a few points: Henslow’s sparrows live in dense grasslands and they are elusive creatures.
Read the full poem, Kenn Kaufman’s ode to Henslow’s Sparrow
Indeed, this sparrow has been playing hide and seek with birdwatchers for two centuries. It is a specialty of the eastern states, with a breeding range (current and historic) extending from the Atlantic to the eastern Great Plains and a short distance north to Canada. It winters entirely in the southeastern states.
Within this range, its known breeding distribution has changed over time. In the early 20th century, Henslow’s Sparrows were locally common in summer along the Atlantic coast from New England to New Jersey, but they have now virtually disappeared from this region. In Ohio they increased dramatically in the 1920s and 1930s, but have since declined. In Kentucky, expansion was seen later, from the 1940s through the 1960s. In the western part of their range, Henslows were first found nesting in Oklahoma in 1987, in Arkansas in 1988 and North Dakota in 2001. States like Minnesota, Illinois, West Virginia, and North Carolina have seen steep increases and declines in the past.
Habitat is the key. To nest, the Henslow’s Sparrow needs areas of tall, dense grass with a thick layer of dead grass on the ground, scattered wildflowers and dead standing stems, but no trees. Within this canopy, the sparrows stay out of sight, except for the singing males, which perch on top of a weed or dead stem barely above the top of the grass . The song is shockingly simple! The males sing at all hours of the day and even all night.
The birds also seek dense winter habitats in the southeast. Open savannahs with tall, scattered pines and an understory of grasses or sedges may be ideal, but such sites need to burn every few years. If they don’t, too much brush will grow for the sparrows’ liking. Pitcher plant bogs are also favored sites. Needless to say, birds are very difficult to see in such places.
Despite their elusive nature, Henslow’s Sparrows are favorites of many experienced birders. Sometimes we are even poetic about them. See the photos and captions in this article for details on how to identify this subtle creature.
What to look for
The size and the shape. A small sparrow with a relatively large beak, large flat head, and short tail.
General color. Olive green wash on the face, contrasting with rich reddish brown tones on the back and wings.
Face model. Distinct black mark set back behind (and separate from) the eye, and two very narrow black whisker bands.
Model of the lower parts. A “necklace” of very fine black streaks on the buff breast, and a few equally fine streaks on the flanks.
Henslow’s Sparrow, adult male. May in Muskingum County, Ohio
This sparrow was discovered in 1820 by John James Audubon, who described it to science and named it after British priest and naturalist John Stevens Henslow. Apparently Audubon never heard the song of the bird. He didn’t miss much. Many North American sparrows have complex and beautiful songs, but Henslow’s Sparrow is famous for having one of the simplest and worst. The song is, however, quite distinctive once learned. Territorial males usually take an exposed perch while singing, providing the best chance to spot and study this elusive creature. Like related species, the Henslow’s Sparrow seems to devote much effort to its modest vocal production, throwing its head back and opening its beak wide to utter a single tsslick!
Henslow’s Sparrow, adult. May in Muskingum County, Ohio
Seen up close, the absence of pronounced markings around the eye gives Henslow’s Sparrow a vacant expression; a very narrow white eyering is rarely visible. The black triangular mark behind the eye is visible but unrelated to other markings, and two very narrow black mustache streaks are also isolated on the plain face. A pale stripe down the center of its crown is rarely evident. Thin black streaks on the buff breast rarely or never meet in a kind of dark central patch. The streaks on the chest help distinguish the Henslow’s Sparrow from the adult Grasshopper Sparrow, but beware, juvenile grasshoppers are heavily streaked and even some adults have dark streaks on the sides of the chest.
Grasshopper Sparrow, adult. May in Muskingum County, Ohio
Very similar to the Henslow’s Sparrow in form and behavior, the Grasshopper Sparrow is much more numerous and widespread. This is a different grassland species, but it seems much more adaptable, occurring in a wider range of open fields, including much drier sites than those used by Henslow. The Grasshopper Sparrow has a predominantly buff, not olive face, usually with a bright yellow patch in front of the eye. It shows barely a hint of dark streaking on the mustache, and only slight streaking on the sides of the chest, so the lower face and underparts are much less marked overall than the Henslow’s Sparrow. A narrow white band in the center of its dark crown is often visible.
Baird’s Sparrow, adult. June in Kidder County, North Dakota
An uncommon specialty of the northern Great Plains in summer, wintering primarily in the prairies of Mexico and Arizona, Baird’s Sparrow is unlikely to overlap with Henslow’s Sparrow, except possibly during migration. Related to Henslow’s sparrows and grasshoppers, it also has a large beak, flat head and short tail. The best field markings for the Baird’s Sparrow are for head and chest colors and patterns. Its head is washed with ocher yellow, contrasting with the whitish throat and chest. Its crown is finely streaked with black, with a gap in the middle revealing a yellow stripe, and the black streaks of the mustache are thick and obvious. Its back and wings lack the strong reddish-brown hues usually shown by Henslow’s Sparrow and Grasshopper Sparrow.
An elusive nomad
Henslow’s Sparrows have altered their long-term distribution as land use practices have altered the landscape. But growing evidence suggests that individuals move from year to year, or even within a single season, more than most birds.
In a recent study, Mark Herse and others, working in the laboratory of bird ecologist Alice Boyle at Kansas State University, conducted thousands of point count surveys in eastern Kansas over two nesting seasons. They found Henslow’s Sparrows at 98 sites, but only four of those sites were occupied over the two years of the study. Moreover, even during the seasons, the birds often changed their location. In three quarters of the sites where cases of Henslow have been discovered, they have only been recorded once.
This nomadic behavior is an adaptation to the changing nature of their habitat. Mature forest birds may use the same territory each year, but Henslow’s Sparrow prefers an early stage in the natural succession of habitats. When a patch of land in eastern North America is cleared, it grows back: first into a grassy field, then into a brushy prairie, and finally into a forest.
Henslow resembles the early stages – dense fields of tall grass, which are maintained only by frequent cutting or burning – so that as their preferred sites thicken or are mown, they must move on to new fields. By remaining free and mobile, they can take advantage of new sites quickly.
