WatchList Methodology and Criteria
Determining the placement of a bird on or off the WatchList is based on the assessment of four factors: population size, range size, threats, and population trend (Panjabi et al. 2005). Each of these factors is scored on a scale of one to five, where one means low vulnerability to extinction due to that factor and five means high vulnerability. For range size and threats, separate scores are calculated for breeding and non-breeding seasons; to create a combined national score, only the highest of the respective breeding and non-breeding scores is used. Thus, the combined score is a sum of four scores and ranges from four to 20.
To be on the WatchList, a species needs a combined score of 14 (or 13 if the population trend score is 5). To be on the list of species of Highest National Concern (Red WatchList), a species needs a combined score of 16, plus a score of eight or more for threats plus trend and a score of eight or more for range size plus population size. To be on the Rare list (Yellow WatchList, in part), a species needs a combined score of 14, a score of eight or more for range size plus population size, and a score of seven or less for threats plus trend. To be on the Declining list (Yellow WatchList, in part), a species needs a combined score of 14 (or 13 if the trend score is 5), a score of seven or more for threats plus trend, and a score of seven or less for range size plus population size.
Global population size estimates came from a variety of sources: waterbirds (Delany and Scott 2006); waterfowl (North American Waterfowl Management Plan Committee 2004; Delany and Scott 2006); shorebirds (Morrison et al. 2006); seabirds (Kushlan et al. 2002); landbirds (Rosenberg and Blancher 2005); and occasionally other sources that were considered more reliable for specific species than the above general references (e.g., USFWS recovery plans). For consistency, score thresholds for all four factors use Partners in Flight thresholds (Panjabi et al. 2005).
Global range size estimates were all calculated from the NatureServe maps (Ridgely et al. 2005). They are adjusted to include range outside the western hemisphere and corrected for major inaccuracies or errors in the maps. NatureServe maps tend to be drawn more generally than are some other map sources, so many species are given larger ranges based on NatureServe, resulting in some species receiving lower range size scores (corresponding to less conservation concern).
Threats were evaluated by the various North American bird conservation initiatives (Brown et al. 2001, Kushlan et al. 2002, Rich et al. 2004) then calibrated to the PIF definitions (Panjabi et al. 2005) for consistency. Only threats pertinent to North American populations were considered.
North American population trends were derived from the Breeding Bird Survey (Sauer et al. 2005), the Audubon Christmas Bird Count, or a combination of the two, if reliability scores for the surveys were high enough (Butcher and Niven 2007). For species that are not well covered by the BBS or CBC, trend information is available from the same sources with population size information: waterbirds (Delany and Scott 2006); waterfowl (North American Waterfowl Management Plan Committee 2004); shorebirds (Morrison et al. 2006, Bart et al. 2007); seabirds (Kushlan et al. 2002); landbirds (Rich et al. 2004); BirdLife data zone (http://www.birdlife.org/datazone/species/index.html); and occasionally other sources that were felt more reliable for specific species than the above general references.
Bart, J., S. Brown, B. Harrington, and R.I.G. Morrison. 2007. Survey trends of North American shorebirds: Population declines or shifting distributions? J. Avian Biol. 38:73-82.
Brown, S., C. Hickey, B. Harrington, and R. Gill, eds. 2001. The U.S. Shorebird Conservation Plan, Second Edition. Manomet Center for Conservation Sciences, Manomet MA.
Butcher, G.S. 2007. Common birds in decline, a state of the birds report. Audubon 109(4):58-62.
Butcher, G.S., and D.K. Niven. 2007. Combining data from the Christmas Bird Count and the Breeding Bird Survey to determine the continental status and trends of North America birds.
National Audubon Society, New York NY. http://www.audubon.org/bird/stateofthebirds/CBID/report.php.
Delany, S., and D. Scott, eds. 2006. Waterbird Population Estimates – Fourth Edition. Wetlands International, Wagingen, The Netherlands.
Kushlan, J.A., M.J. Steinkamp, K.C. Parsons, J. Capp, M. Acosta Cruz, M. Coulter, I. Davidson, L. Dickson, N. Edelson, R. Elliot, R.M. Erwin, S. Hatch, S. Kress, R. Milko, S. Miller, K. Mills, R. Paul, R. Phillips, J.E. Saliva, B. Sydeman, J. Trapp, J. Wheeler, and K. Wohl. 2002. Waterbird Conservation for the Americas: The North American Waterbird Conservation Plan, Version 1. Waterbird Conservation for the Americas, Washington, DC, U.S.A. 78pp.
Morrison, R.I.G., B.J. McCaffery, R.E. Gill, S.K. Skagen, S.L. Jones, G.W. Page, C.L. Gratto-Trevor, and B.A. Andres. 2006. Population estimates of North American shorebirds. Wader Study Group Bulletin 111:67-85.
North American Waterfowl Management Plan Committee. 2004. Strategic Guidance: Strengthening the Biological Foundation. Canadian Wildlife Service, U.S. Fish and Wildlife Service, Secretaria de Medio Ambiente y Recursos Naturales, 22 pp.
Panjabi, A. O., E. H. Dunn, P. J. Blancher, W. C. Hunter, B. Altman, J. Bart, C. J. Beardmore, H. Berlanga, G. S. Butcher, S. K. Davis, D. W. Demarest, R. Dettmers, W. Easton, H. Gomez de Silva Garza, E. E. Iñigo-Elias, D. N. Pashley, C. J. Ralph, T. D. Rich, K. V. Rosenberg, C. M. Rustay, J. M. Ruth, J. S. Wendt, and T. C. Will. 2005. The Partners in Flight handbook on species assessment. Version 2005. Partners in Flight Technical Series No. 3. Rocky Mountain Bird Observatory website: http://www.rmbo.org/pubs/downloads/Handbook2005.pdf.
Rich, T. D., C. J. Beardmore, H. Berlanga, P. J. Blancher, M. S. W. Bradstreet, G. S. Butcher, D. W. Demarest, E. H. Dunn, W. C. Hunter, E. E. Iñigo-Elias, J. A. Kennedy, A. M. Martell, A. O. Panjabi, D. N. Pashley, K. V. Rosenberg, C. M. Rustay, J. S. Wendt, and T. C. Will. 2004. Partners in Flight North American Landbird Conservation Plan. Cornell Lab of Ornithology. Ithaca, New York.
Ridgely, R. S., T. F. Allnutt, T. Brooks, D. K. McNicol, D. W. Mehlman, B. E. Young, and J. R. Zook. 2005. Digital Distribution Maps of the Birds of the Western Hemisphere, version 2.1. NatureServe, Arlington, Virginia, USA. http://www.natureserve.org/getData/birdMaps.jsp.
Rosenberg, K. V. and P. J. Blancher. 2005. Setting numerical population objectives for priority landbird species. Pp. 57-67 in Bird Conservation and Implementation in the Americas: Proceedings of the Third International Partners in Flight Conference, Vol. 1. C. J. Ralph and T. D. Rich, eds. USDA For. Ser. Gen. Tech. Rep. PSW-GTR-191. Pacific Southwest Research Station. Albany, California. 651 pp.
Sauer, J. R., J. E. Hines, and J. Fallon. 2005. The North American Breeding Bird Survey, Results and Analysis 1966 - 2005. Version 6.2.2006. USGS Patuxent Wildlife Research Center, Laurel, MD. http://www.mbr-pwrc.usgs.gov/bbs/.