This sparrow is notable for the moss-green plumage on its head and nape, reddish-brown wings, and abrupt, hiccup-like song. It is inconspicuous, preferring to run through the tall grass, rather than fly, to avoid detection. An unusual characteristic for the sparrow is that it sings at night in the breeding season, its song being one of the few prairie sounds at 1 AM on a dark, moonless night.
Habitat loss is probably the biggest threat to the Henslow’s Sparrow; loss of grasslands through fire suppression, conversion to agriculture or pine plantations, and earlier and more frequent cutting of hayfields have all contributed to a population decline over the last three decades that is among the steepest of any North American grassland bird species. Habitat destruction on the wintering grounds has also contributed to its decline.
The Conservation Reserve Program of the federal Farm Bill has created undisturbed grassland habitat resulting in local increases. In addition, reclaimed strip mines have proved to be suitable as breeding habitat – some grasslands on former strip mines support as many as 2,000 birds. Managed grasslands on military reservations such as Fort Riley, Kansas, and Fort Campbell, Kentucky, also support significant populations.