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Henslow's Sparrow
Ammodramus henslowii
Small and quiet, Henslow's Sparrow is a humble songbird, always close to the ground. Its distinct and complex plumage, one of the few sparrows to show partially greenish color, may reward the patient observer. Few in number and living only in North America, Henslow's Sparrow depends on our willingness to preserve tallgrass habitats.
Henslow's Sparrow is more often heard than seen, though its song is nothing more than a short, hiccupped "tslick." Like other sparrows in its genus, Henslow's is short-tailed and rather chunky, with a flat head and relatively heavy bill. It has a buff breast with dark streaks, an olive-green face, and rufous-toned back and wings. The head is boldly marked with dark lines on the side of the throat, the moustache, behind the eye, and on either side of the crown. The dark brown eye is ringed in white. This small sparrow measures about 5 inches long with a 6.5-inch wingspan and weighs only 0.46 ounces.
A species of tallgrass prairies, agricultural grasslands, and pine savannas of the eastern U.S., Henslow's Sparrow breeds from western New York and Pennsylvania west to southern Wisconsin, eastern Iowa, and eastern Kansas and Oklahoma. Isolated, remnant breeding populations occur in eastern North Carolina and in scattered locations from the Delmarva Peninsula and (formerly) into Massachusetts. It once bred regularly throughout New England and New Jersey but is now largely extirpated. An isolated population that once bred in coastal Texas and was considered by some to represent a unique subspecies has since been lost to commercial land development. In winter the species occurs in a belt extending from North Carolina west to eastern Texas. Populations breeding east of the Appalachian Mountains may represent a distinct subspecies, A. h. susurrans.
This species occupies ephemeral grassland habitats. Specific grassland features include: unbroken patches of at least 75 acres which are part of larger tracts (at least 400 acres); native grass species like little bluestem, prairie dropseed, blue joint, and Indian grass; few woody plants; substantial litter and old, erect grass stems; and fairly deep weed and grass growth. Periodic burning, light grazing, and controlled mowing produce these conditions. Reclaimed strip mines, fallow fields, powerline cuts, and restored prairie can also be used by this sparrow. Winter habitats include coastal grasslands, pine savannah, and pitcher plant bogs.
During the day, Henslow's Sparrow forages on the ground, preferably in grasses between four and six inches tall. During the warmer months, insects dominate the diet: beetles, caterpillars, centipedes, crickets, grasshoppers, spiders, and true bugs. Seeds from many species of grasses, sedges, and weeds are also consumed in summer, but are most important in winter, including flax, nutrush (genus Scleria), panic grass, small fruit beggarticks, star sedge, tickseed, toothache grass, and wiregrass.
From March through July, males arrive on the breeding grounds and establish territories in loose colonies by singing, usually from within the grass. The ˝ to 1˝-acre territories often shift, especially with subsequent broods (up to three per season). Due to its secretive nature, much of its breeding history remains unknown. Courtship includes a "call of intimacy," wing fluttering, and a review of potential nest sites. Under a clump of grass and in dry, matted grasses, the female typically constructs the nest from course, dry grasses and lines it with finer blades. For about 12 days, the female incubates 2-5 off-white eggs marked with warm browns and light grays.
The downy gray hatchlings are helpless and require brooding for about four days. With a steady supply of insects, both adults feed the young and remove or eat their fecal sacs. Young Henslow's Sparrows leave the nest in about nine days. After leaving the nest, fledglings are so well concealed that researchers have yet to describe their life history prior to migration!
Because Henslow's Sparrow is so hard to find during migration, much of its migratory behavior has yet to be described. All individuals appear to migrate. Spring migration begins in March but peaks in April. Fall migrants probably depart sometime in September and start arriving in the lower wintering range in October. A few Henslow's Sparrows linger in the breeding range into December.
Herkert, J. R. 2003. " Effects of management practices on grassland birds: Henslow's Sparrow." Northern Prairie Wildlife Research Center, Jamestown, ND. Northern Prairie Wildlife Research Center Online. (Version 12DEC2003).
Herkert, J. R., P. D. Vickery, and D. E. Kroodsma. 2002. Henslow's Sparrow ( Ammodramus henslowii). In The Birds of North America, No. 672 (A. Poole and F. Gill, eds.). The Birds of North America, Inc., Philadelphia, PA.
Johnson, Eric I. Effects of Fire on Habitat Associations, Abundance, and Survival of Wintering Henslow's Sparrows Ammodramus henslowii in Southeastern Louisiana Longleaf Pine Savannas. Louisiana State University, Master's Thesis: May 2006. 82 pages. Accessed 30 June 2007.
Sibley, David Allen. 2000. The Sibley Guide to Birds. Alfred A. Knopf, New York.
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Due to its secretive behavior and preference for thick grassy habitats, this species is hard to census. Between 1966 and 2005, Breeding Bird Survey (BBS) data indicate an average range-wide decline of 7.9% each year. Northern populations have fared the worst, with average annual losses during this period of 13.8% in New York, 4.7% in Ohio, 9.9% in Wisconsin, and 12% in Michigan. From 1966 to 2005, small increases were recorded through most of the southern breeding range from Oklahoma to Ohio. Populations are most dense in remnant tallgrass prairie across the border of southeastern Kansas and northeastern Oklahoma, in eastern Missouri, and from southern Illinois into western Pennsylvania
In the 1800s, as eastern forests were cleared and farmed with traditional European practices, the population of Henslow's Sparrows grew. It was considered common to abundant across most of its breeding range at that time. As farming has declined over the past century in the northeast and land has either been developed or regenerated to forests, this species along with many other grassland dependent birds has significantly declined.
Henslow's Sparrow has suffered most from the loss of breeding habitat to industrialized agriculture, urban sprawl, and the regrowth of eastern forests. At the same time, southeastern pine savannah habitats have been converted to pine plantations, which are unsuitable for Henslow's Sparrows in winter. Wintering habitats along the Gulf Coast, like moist pine savannas and pitcher plant bogs, have also been ruined. Ninety-seven percent of Gulf Coast bogs either no longer exist or are unable to support this songbird.
Between the 1830s and the late 1990s, Illinois, Indiana, Iowa, Minnesota, and Wisconsin lost 99.9% of their tallgrass prairie. Once abundant in Illinois, Henslow's Sparrow declined an estimated 94% from 1957-1975, and in this period the remnant of Illinois' prairie was cut by 65-75%. Despite these losses, the U.S. Fish and Wildlife Service declined to list Henslow's Sparrow under the Endangered Species Act in 1998. Of the 32 states and one province (Ontario) within its historic range, 30 afford it conservation status, including nine Endangered and nine Threatened listings. Partners in Flight deems Henslow's Sparrow a Highest Priority and in 2000 began designating grassland bird conservation areas, measuring 2,000 acres or more, for this species and others.
Efforts are underway in parts of the Midwest to restore native tallgrass prairie habitat for Henslow's Sparrow, as well as others like the Greater Prairie-Chicken. Established in 1996, the Midewin National Tallgrass Prairie restores and refurbishes grassland on an unprecedented scale, working with approximately 19,000 acres. Its success may lead the way to the rehabilitation of entire prairie landscapes. The Conservation Reserve Program has also been a successful tool for maintaining Henslow's Sparrow habitat and for engaging private landowners on working lands. In addition, abandoned mine lands provide suitable grassland for Henslow's Sparrows in some states such as Indiana and Pennsylvania.
In late spring and early summer, look for the Henslow's Sparrow in the remnants of a tallgrass prairie near you.
Support Audubon's Important Bird Area (IBA) program, a vital tool for the conservation of Henslow's Sparrows. Explore an IBA with significant populations of this little songbird, like New York's Jefferson County Grasslands, the Fort Riley Military Reservation in Kansas, and Florida's Apalachicola and Tates Hell Forests.
If you own or manage tallgrass prairie with the range of the Henslow's Sparrow, consider the best management practices suggested by the USFWS or the Rocky Mountain Bird Observatory.
Find out about actions you can take including Audubon programs and activities.
For an example of how the Conservation Reserve Program benefits farmland and grassland species like Henslow's Sparrow, read about Audubon's profile of the Prairie King.
Learn more about this species and other birds through these resources.
Herkert, J. R., P. D. Vickery, and D. E. Kroodsma. 2002. Henslow's Sparrow ( Ammodramus henslowii). In The Birds of North America, No. 672 (A. Poole and F. Gill, eds.). The Birds of North America, Inc., Philadelphia, PA.
Herkert, James R. "Status and Habitat Selection of Henslow's Sparrow in Illinois." Wilson Bulletin 106:l (1994) 35-45.
Sauer, J. R., J. E. Hines, and J. Fallon. 2005. The North American Breeding Bird Survey, Results and Analysis 1966 - 2005. Version 6.2.2006. USGS Patuxent Wildlife Research Center, Laurel, MD. Accessed 30 June 2007.
Tucker JW & Robinson WD. "Influence of season and frequency of fire on Henslow's Sparrows ( Ammodramus henslowii) wintering on Gulf Coast pitcher plant bogs." Auk 120:1.(2003) 96-106.
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