Long-Term Bird Assemblage Trends in Areas of High and Low Human Population Density

Figure 1

To illustrate our route selection process, the main map shows portions of two ecoregions containing breeding bird survey (BBS) routes used in this study. Within each ecoregion, we selected one BBS route in an LHPD area and one in an HHPD area (see Methods for definitions). Shaded polygons on main map indicate county population density. Inset shows all 12 ecoregions used for the study.