Henslow's Sparrow Relative Abundance Map
Source: North American Breeding Bird Survey (BBS)
Map Description:
The enigmatic Henslow's Sparrow is another inconspicuous occupant of grassland habitats in eastern and central North America. With its furtive habits and plain song, this species is easily overlooked. Only sketchy information is available on its historic status and distribution. Its original breeding range may have consisted of tall grass prairies in the midwest and various grassland habitats along the mid-Atlantic coastal plain (Hyde 1939). Deforestation allowed it to expand its breeding range in the Great Lakes region, primarily during the first half of the twentieth century. After 1950, its populations have been declining through most of its range (Andrle and Carroll 1988, Brewer et al. 1991, Cadman et al. 1987). However, reclaimed strip mines provide suitable habitats for this species, and the bulk of its remaining populations occupy these habitats in eastern Ohio and western Pennsylvania (Brauning 1992, Peterjohn and Rice 1991).

Sauer, J. R., B. G. Peterjohn, S. Schwartz, and J. E. Hines. 1995. The Grassland Bird Home Page. Version 95.0. Patuxent Wildlife Research Center, Laurel, MD

Cautions for this Product:
Analysis and interpretation of BBS data is tricky, because the survey incorporates information from a huge geographic area and the survey varies greatly in quality of information over the area. To document some of the problems with the analyses of BBS data, and help interpret the results presented, a series of help files is provided with information on the survey, discussion of problems with analysis, and details on how the presented information should be interpreted.
For Further Information: