Figures 2a, 2b. The chance of encountering a forest or grassland songbird species in their breeding grounds, as a function of the continuous area of trees or meadow. In each case the upper and lower curves distinguish between the relative sensitivity of songbird species to habitat fragmentation, with examples given in Table 2, p. 9. From J.R. Herkert, R.E. Szafoni, V.M. Kleen, and J.E. Schwegman, Habitat Establishment, Enhancement and Management for Forest and Grassland Birds in Illinois. Illinois Department of Conservation, Springfield, Natural Heritage Publication No. 1, 19 pp, 1993.