Henslow's Sparrow

New York Status: Threatened
Federal Status: Not Listed

Description

Two distinctive characters help in identification of this sparrow: the flat-headed profile and the olive-colored head. The wings are rust-colored and the buffy breast and sides are streaked with black. Juveniles have the characteristic rust-colored wings and olive head of an adult, but its underparts are not streaked.

The call is a weak, cricket-like, metallic "tslit" or "tsi-like." The ventriloquial quality of the voice and the secretive nature of the Henslow's Sparrow make this bird an easy one to overlook and difficult to observe.

Life History

During the courtship period, the male hops up and down with nesting material in his bill and sings to the female. He then leads her on foot to several potential nesting sites which he indicates by rapidly fluttering his wings. The female approves one site and builds a nest there over the next 5-6 days. She incubates 3-5 eggs for a period of 9-11 days. The young fledge in about 9-10 days. Henslow's sparrows have two broods each year. Nesting occurs in loose colonies which may be the result of clumped food resources. The species is believed to be monogamous.

Distribution and Habitat

Henslow's sparrows breed from South Dakota, Minnesota, Wisconsin, Michigan, Ontario, and Massachusetts; south to Kansas, Missouri, Illinois, Kentucky, West Virginia, Virginia, and North Carolina; and locally in Texas. In New York, populations are very localized and found primarily in the central and western parts of the state, especially the Appalachian Plateau and Great Lakes Plain. In Eastern New York, it may also be found in the Mohawk Valley.

Generally, its habitat consists of fallow, weedy, often moist fields and meadows.

Breeding occurs in a variety of habitats, including:

• tall, dense grass
• upland weedy hayfields
• pastures without shrubs
• wet meadows
• drier areas of salt marshes
• grassy fields
• sedge covered hillsides with recently planted pine seedlings
• lightly grazed pastures

Status

In the early 1900s, Henslow's sparrows were uncommon and rare in all parts of New York State. Populations increased from 1920 to 1940, with several new colonies appearing throughout the state, including Long Island, Central and Western New York, and corridors along the Hudson, Delaware and Susquehanna rivers. Populations began to decline in the 1950s.

Breeding Bird Survey data through 1989 have shown a steady, statistically significant declining trend in New York State and throughout the Northeast. The Henslow's Sparrow has been on the American Birds' Blue List (Special Concern) since 1974. It was listed in New York State as a species of special concern in the early 1980s and was re-classified as threatened in 1999. Populations continue to decline.

Management and Research Needs

The major threat to Henslow's sparrows is loss of breeding habitat as agricultural grasslands are developed or abandoned to subsequently revert to forests. This species deserves special attention, not only because the primary breeding habitat is a transitory, early successional stage, but because comparatively fewer fields are allowed to lie idle today for a sufficient number of years. Management of habitat through burning has both positive and negative effects. While it is beneficial in stimulating herbaceous growth, it also reduces the amount of ground litter which Henslow's sparrows seem to prefer.

Henslow's sparrows utilize lightly grazed pastureland. A declining dairy industry in New York State will reduce the need for pasturage. More frequent mowing will be required to replace grazing and, if economically infeasible, pastures will be allowed to revert back to forests. The effects of this trend need to be addressed.