Appendix D. Detection indices (percentage years a species was detected on Breeding Bird Survey routes that were sampled at least seven times during 1994–2003) for ten songbird species vs. mean human footprint class (minimal to high human footprint influence).
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| FIG. D1. Detection indices (percentage years a species was detected on Breeding Bird Survey routes that were sampled at least seven times during 1994–2003) for ten songbird species vs. mean human footprint class (minimal to high human footprint influence). Shown are scatter plots with LOWESS trend lines for (1) four synanthropic species (terminology follows Johnston 2001): (A) "full" = House Sparrow (Passer domesticus), "casual" = House Finch (Carpodacus mexicanus), and "tangential" = Western Kingbird (Tyrannus verticalis) and Bullock’s Oriole (Icterus bullockii); (2) four forest-dwelling species (B) = Brown Creeper (Certhia americana), Hermit Warbler (Dendroica occidentalis), Grace’s Warbler (Dendroica graciae), and Winter Wren (Troglodytes troglodytes); and (3) two shrubsteppe obligate species (C) = Sage Sparrow (Amphispiza belli) and Brewer’s Sparrow (Spizella breweri). Because Breeding Bird Survey routes follow roads, including dirt roads, none of the species occur in the near roadless human footprint class 1. |
LITERATURE CITED
Johnston, R. F. 2001. Synanthropic birds of North America. Pages 49–67 in J. M. Marzluff, R. Bowman, and R. Donnelly, editors. Avian ecology and conservation in an urbanizing world. Kluwer Academic Publishers, Boston, Massachusetts, USA.