Henslow's Sparrow (Ammodramus henslowii) held territory this June alongside…
June 25, 2026·
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(Ammodramus henslowii) held territory this June alongside and two declining checkerspots — and — along with flowering and . These species signal something rare: intact native prairie holding its ground in the Pecatonica watershed. The sparrow's presence is particularly striking — its population collapsed by 95% as fire-maintained grasslands were plowed under, leaving it nearly extirpated from the region.
also recorded here. These birds depend on the open structure and native forb diversity that traditional Indigenous burning once sustained. This patch still carries that signature — evidence that long-term stewardship can slow and even reverse some losses, though the wider landscape remains fragmented and threatened by erosion. The East Branch itself still carries the burden of impairment, but the upland prairie quality here offers the river real refuge and recovery potential.
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shows crisp streaking on white underparts and a yellow patch in front of the eye that neither of the others has.
What the birds at Peck Farm are doing is fueling up. Henslow's Sparrow breeds in Illinois. It needs large tracts of grass left unmowed and unburned long enough to build a thick mat of dead stems and litter, and the state's breeders have mostly left by late August. Birds still in northern Illinois in September are almost certainly migrants passing through at night toward wintering grounds on the southeastern coastal plain. In September they are still eating mostly insects, crickets and short-horned grasshoppers above all, plus beetles and caterpillars. The shift to a seed diet of wiregrass, sedge, ragweed and smartweed comes in winter, farther south.
The litter layer is the whole story for this bird. It nests low in the grass under standing dead stems from prior years, and it will not use a field that was burned or hayed the same season. That puts it in tension with prairie management, because tallgrass prairie needs fire to keep shrubs and trees out. Studies of burned grasslands show Henslow's numbers dip the first summer after a burn, peak in the second and third years as the thatch rebuilds, and fall off again by the fourth as the stand gets too rank. The answer managers have settled on is to burn in rotation, a third of the ground at a time, so some patch is always in the two-to-three-year sweet spot. The Geneva Park District manages roughly 300 acres of prairie across its properties and burns about 100 acres every 18 months, which is that rotation in practice.
Rangewide, the species lost enormous ground through the twentieth century as prairie and hayfield went under the plow, and estimates from Partners in Flight put its global population at roughly 410,000 birds, though figures vary by source. Since the early 1990s, idle grassland set aside under the Conservation Reserve Program has driven local increases across parts of the Midwest. Some Bird Conservation Network surveys in the Chicago region have suggested an increase over the past fifteen years, though the trend is not consistent across all survey sites and sizeable populations remain confined to large grasslands. The prairie at Peck Farm is far smaller than that. It is a place a migrant can drop into for a few days on the way south, and that depends on the grass being there, thick and unburned that season, when the bird arrives.
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