Bobolink Relative Abundance Map
Source: North American Breeding Bird Survey (BBS)
Map Description:
Bobolinks are conspicuous summer residents of hayfields, lightly grazed pastures, tall- and mixed-grass prairies, reclaimed strip mines, and similar habitats dominated by tall grasses. As is true for many other grassland birds, this species underwent a noticeable population increase and range expansion in eastern North America during the nineteenth century when agricultural fields dominated the deforested landscape (Andrle and Carroll 1988, Brewer et al. 1991, Peterjohn and Rice 1991). Bobolink population trends were reversed during the twentieth century, especially after 1940 when changing agricultural practices greatly reduced the amount of suitable grassland habitats for this species.

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: