Wildlife Action Plan 2015 Revision Process White Paper
3. Range Size. As noted for population size, geographic distribution is an important mea- surement of a species’ rarity (Manne and Pimm 2001; 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 North Carolina. Te intent in using this metric is to recognize the importance of species with small range sizes because they may be more at risk of extinc- tion (Breininger et al. 1998) . Where a species has distinct breeding and nonbreeding ranges (e.g., migratory birds, anadromous fsh), the smaller range size should be considered during this evaluation. Te 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)?
(a) < 100 km 2 (< about 40 mi 2 )
(b) 100–250 km 2
(c) 250–1,000 km 2
(d) 1,000–5,000 km 2
(e) 5,000–20,000 km 2
(f) 20,000–200,000 km 2 [North Carolina has 125,919.81 km 2 ]
(g) 200,000–2,500,000 km 2
(h) >2,500,000 km 2 [Te US has about 6.8 million km 2 ]
(i) Unknown
4. Distribution Trend (long-term). A species may be more vulnerable to extinction when its range becomes fragmented or too small to support its population. Te persistence of rare species may be more limited when habitat impacts are long-term and the fragmenta- tion leads to increased local competition between species for reduced resources (Hanski 2008; Wahlberg et al. 1996; Millsap et al. 1990) . Tis evaluation considers changes to distribution because of habitat loss or change that may have occurred from European settlement up to recent historical periods more than 20 years ago. For example, the fragmentation and reduction of Longleaf Pine acreage that began with European settlers using the forests as a resource for military naval stores (Frost 1993) has resulted in signifcant impacts to distribution of wildlife species adapted to this community
922
2015 NC Wildlife Action Plan
Made with FlippingBook - professional solution for displaying marketing and sales documents online