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Centronyx henslowii (Audubon, 1829)
Henslow's Sparrow
Federal Protection: No US federal protection
State Protection: Rare
Global Rank: G4
State Rank: S2
Element Locations Tracked in Biotics: Yes
SWAP 2015 Species of Greatest Conservation Need (SGCN): Yes
SWAP 2025 Species of Greatest Conservation Need (SGCN): Yes
2025 SGCN Priority Tier: High Conservation Concern
Element Occurrences (EOs) in Georgia: 13
Habitat Summary for element in Georgia: Grassy areas, especially wet grasslands, pitcher plant bogs, pine flatwoods, power line corridors in CP. Requires open veg at ground level with grass canopy above
This sparrow has an olive-green head with distinct white eye-ring, chestnut brown back, buffy upper breast and flanks with black streaking, and a whitish throat, lower breast, and abdomen. Two broad black crown stripes run along the top of the head. These stripes are solid from the base of the bill to the back of the head then turn to streaking from the back of the head down to the nape. Two thin black malar (mustache) stripes and two somewhat wider black streaks or patches adorn the face and side of the head. Feathers on the back are chestnut with black centers with a contrasting white fringe on the edge. Tail feathers are chestnut to brown in color with very pointed tips. Males and females are indistinguishable by plumage in winter and plumage does not vary substantially between the breeding and non-breeding seasons.
The grasshopper sparrow (Ammodramus savannarum) can look somewhat similar to the Henslow's sparrow, but it has a buff and gray face (not olive like the Henslow's), buffy throat, more buff color on the flanks, and lacks the dark face stripes and the dark streaking on the upper breast and flanks. LeConte's sparrow (Ammospiza leconteii) also looks similar to the Henslow's sparrow, but its face is ochre or yellow-buff as are its flanks. The face has pale gray lores and auriculars and lacks the two dark mustache stripes of the Henslow's sparrow. Its back is brown, not chestnut, and has pale broad vertical stripes.
Breeding habitats include tallgrass prairie, lowland prairie, marshes, meadows and weedy pastures in the western part of its breeding range and coastal marshes, swamps, dry fields, low wet meadows, weedy hayfields and pastures, clear-cut pocosins, and similar sites in the eastern portion of the breeding range. Generally, sites are characterized by tall, dense grasses and forbs, a well-developed litter layer, standing dead vegetation, and little or no woody vegetation. In winter this species uses open pine flatwoods, pitcher plant bogs, power line rights-of-way and fields with dense grassy groundcover, and similar areas. Sites that are regularly burned or that have areas of damp or moist soils seem to be preferred.
Mostly insects during the breeding season, particularly grasshoppers and beetles; probably also some grass and forb seeds. In winter mostly grass seeds, but also seeds of sedges, smartweed, and ragweed, some fruit, and invertebrates including insects, spiders, and small snails.
The nesting season usually begins in late April when the female constructs a small cup nest out of dead grass. It is normally built on top a layer of litter several centimeters thick in a dense clump of grass. Construction takes about 4-6 days after which 2-5 eggs are laid. Eggs are incubated for about 10-12 days before they hatch and young usually fledge at 9-10 days post-hatching. In fall, most birds leave the breeding site by October, arriving at wintering areas in late October or November. This species is very difficult to see during winter due to its skulking behavior where it most often runs through and under dense grass rather than fly. Birds may start to leave wintering areas in early March, and most are gone before the end of April.
Probably the best method to use to survey wintering Henslow’s sparrows is called flush-netting, a technique that includes dragging a long, weighted rope through the grass between two people. When a bird is flushed it will usually fly a short distance and then drop back into the grass. By noting where it lands it can quickly be surrounded by several people and flushed into a mist net erected nearby. The bird can then be banded, examined, and released. This technique has been used effectively over the past 9 years at Paulks Pasture, Townsend, and Moody Forest WMAs to track local population size and site return rates. Flush-netting is also being used to test the effectiveness of a habitat suitability model developed by DNR and the Georgia Cooperative Fish and Wildlife Research Unit at the University of Georgia. This model uses remotely sensed data from satellite imagery and other sources to predict potential habitat areas along powerlines. Areas that the model deems suitable are surveyed to determine whether Henslow’s sparrows are present. If this model is successful in accurately predicting wintering habitat it will allow us to generate population estimates and more easily find new wintering sites.
This bird breeds throughout much of the central and eastern Midwest, along the very northern fringe of the Southeast, in much of New York and Pennsylvania, and southwestern Ontario, Canada. Isolated breeding populations occur in New Jersey and North Carolina and very scattered and local breeding may occur in several states in the Northeast. Wintering birds occur in the Southeast Coastal Plain from North Carolina to eastern Texas and portions of the Lower Mississippi River Valley.
The Henslow's sparrow has lost much of its breeding habitat and probably much of its wintering habitat as well. The tallgrass prairie, its historic nesting stronghold, has all but been wiped out and wet meadows and other native grasslands have suffered similarly. More frequent mowing of hayfields, shorter crop rotations, and conversion of suitable habitats to row crops has significantly decreased the amount of suitable human-made habitat. On its winter grounds dense stocking of pines, lack of prescribed fire, draining of pitcher plant bogs and other wetlands, and unfavorable changes in power line right-of-way maintenance procedures all reduce the dense grassy groundcover this bird prefers. A very new threat is the conversion of grassland breeding habitat that was in the Conservation Reserve Program to corn production due to an increased demand for biofuel.
| Threat 1 | Threat 2 | Threat 3 | |
|---|---|---|---|
| General Threat | Agriculture & aquaculture | Agriculture & aquaculture | Transportation & service corridors |
| Specific Threat | Wood & pulp plantations | Wood & pulp plantations | Utility & service lines |
Paulk's Pasture, Townsend, Moody Forest, and Mayhaw WMAs, Birdsong Nature Center (Thomas County), and Ft. Stewart Army Base. There are likely other sites on conservation lands.
Habitat loss on the breeding and wintering grounds is the most significant factor affecting Henslow's sparrow populations. Most of its prairie habitat was lost to agriculture during the late 1800s and early 1900s when it was plowed under so crops could be grown. Only about 10 percent of the open pine forests, savannas, and other suitable native grasslands in the Southeast remain and these were its main wintering habitats. Fortunately, in some instances this species has adapted to using agricultural and silvicultural lands that provide the dense grassy groundcover it needs. Hayfields and pastures can serve as breeding sites and power line corridors often offer suitable habitat for wintering birds. Despite its ability to adapt to human-generated habitats, Breeding Bird Survey (BBS) data suggest that survey-wide its populations may have declined by 1.5 percent per year from 1966-2015. However, caution should be used when interpreting this trend since very low numbers along BBS routes make this trend estimate less robust and reliable.
In Georgia, wintering habitat can be maintained in pine forests by thinning and regularly burning sites with suitable soil conditions. There are thousands of miles of power line corridors in the southern portion of the state and many of these could be burned, mowed, or otherwise managed to encourage a dense grassy groundlayer suitable for wintering birds. Restoration of natural sites such as pitcher plant bogs and wet savannas should be encouraged on state, federal, and private lands whenever possible. Research on winter micro-habitat preferences, intra-seasonal site fidelity, movement patterns, and diet were initiated by DNR and Georgia Southern University in 2019. This study is using fine scale vegetation structure measurements to determine preferred micro-habitat and nanotags (tiny radio-transmitters weighing <0.3 g) to track fine-scale movement patterns on wintering territories. Fecal samples are being tested using advance genetic analysis to determine what plant species are present in the diet. All this is being tied with fire return intervals and other land management practices to provide information to guide habitat management activities. The results of this research should allow us to determine appropriate prescriptions for burning, particularly fire return intervals, as well as appropriate techniques for mowing, use of herbicides, and other methods to maintain habitat for this rare sparrow.
Burleigh, T. D. 1958. Georgia Birds. University of Oklahoma Press, Norman. 746pp.
Herkert, J. R., P. D. Vickery, and D. E. Kroodsma. 2018. Henslow’s Sparrow (Centronyx henslowii) verson 1.1. In The Birds of North America (P. G. Rodewald, Editor). Cornell Lab of Ornithology, Ithaca, NY.
Hyde, A. S. 1939. The life history of Henslow's Sparrow. Passerherbulus henslowi (Audubon). University of Michigan Miscellaneous Publication, Ann Arbor.
McNair, D. B. 1998. Henslow's Sparrow and Sedge Wren response to a dormant-season prescribed burn in a pine savanna. Florida Field Naturalist 26:46-47.
Plentovich, S., N. R. Holler, and G. E. Hill. 1999. Habitat requirements of Henslow's Sparrows wintering in silvacultural lands of the Gulf Coastal Plain. Auk 116:109-115.
Plentovich, S. M., N. R. Holler, and G. E. Hill. 1998. Site fidelity of wintering Henslow's Sparrows. Journal of Field Ornithology 69:486-490.
Robins, J. D. 1971. A study of Henslow's Sparrow in Michigan. Wilson Bulletin 83:39-48.
Sauer, J. R., D. K. Niven, J. E. Hines, D. J. Ziolkowski, Jr, K. L. Pardieck, J. E. Fallon, and W. A. Link. 2017. The North American Breeding Bird Survey, Results and Analysis 1966-2015. Version 2.07.2017 USGS Patuxent Wildlife Research Center, Laurel, MD.
Zimmerman, J. L. 1988. Breeding season habitat selection by the Henslow's Sparrow (Ammodramus henslowii) in Kansas. Wilson Bulletin 100:17-24.
Todd M. Schneider
T. Schneider, July 2010: original account
K. Owers, July 2010: updated status and ranks, added picture
T. Schneider, May 2019: added photo 1
T. Schneider, December 19, 2019: modified and edited text