Piping Plover - U.S. Fish and Wildlife Service

3. Evidence that the discrete population segment represents the only surviving natural
occurrence of a taxon that may be more abundant elsewhere as an introduced population
outside its historic range, or
4. Evidence that the discrete population segment differs markedly from other populations of
the species in its genetic characteristics.
Having found evidence that the Great Lakes and Northern Great Plains populations of C. m.
circumcinctus are discrete, we consider whether each is significant to the subspecies as a
whole. In particular, we evaluate evidence that loss of the Great Lakes or Northern Great
Plains population would result in a significant gap in the range of the taxon. We also
examine evidence that the Great Lakes population persists in an ecological setting that is
unique for C. m. circumcinctus.
Evaluation of population loss resulting in a significant gap in the range of the taxon
Northern Great Plains piping plovers currently breed in eight states and three Canadian
provinces (Elliott-Smith et al. 2009). Their range extends about 1,000 miles (1,600 km) from
north to south and spans more than 800 miles (1,300 km) from west to east. There is no
estimate of the historical population or carrying capacity of Northern Great Plains habitat, but
the significance of the population is evident from the 2006 estimate that it constituted 98% of
C. m. circumcinctus (Elliott-Smith et al. 2009).
Although its current range is much reduced, the Great Lakes population once spanned about
800 miles (1,300 km) from east to west, inhabiting eight states and the Province of Ontario
and breeding on all five Great Lakes. Russell (1983) estimated a total population of 492-682
breeding pairs in the Great Lakes region in the late 1800s. Bull (1974) reported 26 pairs at
the eastern end of Lake Ontario, New York, in 1935. At the other extreme end of the Great
Lakes, small numbers of pairs nested in Duluth Harbor, Minnesota, as recently as the early
1980s (B. Eliason, Minnesota Dept. of Natural Resources, pers. comm. 1999 in USFWS
2003). Some biologists believe that Russell’s estimates may be high (S. Matteson,
Wisconsin Dept. of Natural Resources, pers. comm. 1988 in USFWS 2003), but it is evident
that the range of the Great Lakes population was significant. Furthermore, critical habitat for
the Great Lakes piping plover population encompasses the full geographic extent of this
population’s U.S. historic range, from Minnesota to New York (USFWS 2001a).
Twenty years of banding observations also show that neither the Northern Great Plains nor
the Great Lakes population would recolonize the other if one was lost. The absence of
immigration to abundant vacant habitat in the Great Lakes over more than 25 years is
particularly striking. Both the Northern Great Plains and the Great Lakes constitute a
significant part of the range of C. m. circumcinctus, and loss of either would result in a
significant retraction in the range of the subspecies; for example, loss of the Great Lakes
population could potentially contract the range of C. m. circumcinctus by over 800 miles
(1,300 km).
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