Reference Document 3-1
Appendix 3
Metric 2. Population Size, Range Wide. For our use in this evaluation, range is considered to be a geographic area represented by the outermost boundaries that encompass where a species occurs naturally (Suring et al. 2011) . Efforts to evaluate a species’ rarity can include measurements of population size as represented by geographic distribution and abundance (Manne and Pimm 2006, Witte and Torfs 2003, Kunin 1998) . Considering population size range-wide provides a comparison of how well a species population is doing overall when compared with populations within the state (Crain et al. 2011) . The answer scale is adopted from the NatureServe evaluation tool (NatureServe 2012a) . This metric recognizes the importance of a species where it has overall low population sizes in other parts of its range (global or regional) but it may have a larger population within the state. For example, populations occurring within NC may be relatively large and represent a significant portion of the total known population for a species which has a range beyond the state and may be experiencing declines or have low numbers in those areas (e.g., Eastern Hellbenders, Sanderlings). The opposite may also be true – the population size in North Carolina may be small, but the overall population range-wide is large. For example, Eastern Coral Snake populations in North Carolina are considered critically imperiled, but it is common in parts of its range outside the state and does not appear to be significantly threatened elsewhere (NatureServe 2012b) . Scores are assigned based on the estimated number of adults throughout the species’ range.
What is the estimated number of adults within the species’ range?
(a) 1 – 50 individuals (b) 50 - 250 individuals
(c) 250 - 1,000 individuals (d) 1,000 - 2,500 individuals (e) 2,500 - 10,000 individuals (f) 10,000 - 100,000 individuals (g) 100,000 - 1,000,000 individuals (h) >1,000,000 individuals
Metric 3. Range Size . As noted for population size, geographic distribution is an important measurement of a species’ rarity (Manne and Pimm 2006, Witte and Torfs 2003, Kunin 1998) . Range size considers the most restricted area over which the species is distributed, including areas where it occurs outside NC. The intent in using this metric is to recognize the importance of species with small range sizes because they may be more at risk of extinction (Breininger et al. 1998) . Where a species has distinct breeding and nonbreeding ranges (e.g., migratory birds, anadramous fish), the smaller range size should be considered during this evaluation. The answer scale is adopted from the NatureServe evaluation tool (NatureServe 2012a) . Scores are assigned based on the area over which the taxon is distributed, including watershed size for aquatic species. What is the estimated area of distribution (range size)?
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2025 NC Wildlife Action Plan
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