American Bison - Buffalo Field Campaign

Sixty-two plains bison and 11 wood bison conservation herds
were enumerated (Figure 7.1 and Appendix A). Although
the number of plains bison conservation herds has steadily
increased over time, the number of individuals in conservation
herds has changed little since 1930 (Freese et al. 2007). In 2008,
we estimated there were 20,504 plains bison and 10,871 wood
bison in conservation herds. Among plains bison there were
9,227 breeding age females (two years old and older), 4,121
mature males (seven years old and older) and 1,230 subadult
males (four to six years old). Among wood bison there were
4,892 breeding age females, 2,609 mature males and 652
subadult males.
Since conservation efforts began in the early 1900s, wood
bison numbers have fluctuated independently of the number
of conservation herds (Figure 7.2). Peak abundance occurred
Figure 7.2 Numbers of herds and individual plains bison (upper panel)
and wood bison (lower panel) in North America, 1890-2008. Sources
for wood bison data: Novakowski 1978; Wood Bison Recovery Team
1987; Reynolds and Hawley 1987; Van Camp 1989; Larter et al.
2000; Gates et al. 2001; www.nwtwildlife.com/NWTwildlife/bison/
woodbuffalopark.htm accessed 15 January 2009, and 2008/2009 data
from agencies. Plains bison data follow Freese et al. 2007 and current
status data from agencies.
Plate 7.1 Wood bison near the northern extent of their range in the
Yukon, Canada. Photo: Tom Jung.
from the 1940s to early 1970s following the introduction of more
than 6,000 plains bison into Wood Buffalo National Park (WBNP)
in the late 1920s. The number of bison in the Greater Wood
Buffalo National Park area declined after 1971 when predator
management ceased (Carbyn et al. 1993). The number of wood
bison conservation herds has increased to 11. However, there
are still more bison in the WBNP and Snake River Lowlands
(SRL) metapopulation (6,141 animals), which is infected with
bovine tuberculosis (BTB) and brucellosis, than in the nine
disease-free reintroduced populations (4,730 animals).
The number of bison under commercial propagation has
outnumbered those in conservation herds since about 1970
(Freese et al. 2007). In 2006, there were 195,728 bison on 1,898
farms reporting in the Canadian National Census (Statistics
Canada, www.statcan.gc.ca/daily-quotidien/080125/t080125b-
eng.htm, accessed 4 December 2008). The U.S. Department of
Agriculture’s 2007 Census of Agriculture reported 198,234 bison
on 4,499 farms (http://www.agcensus.usda.gov/, accessed
10 February 2008). Thus, based on these numbers, there are
nearly 400,000 privately owned bison on around 6,400 farms in
Canada and the U.S.
7.3 Geographic Status
The original range of bison extended from lowland meadows
in interior Alaska to desert grasslands in Mexico, and included
areas as far east as New York and as far west as California
(List et al. 2007; Reynolds et al. 2003). The original range of
American bison spanned an area estimated by Sanderson et al.
(2008) to be 9.4 million km 2 , and encompassed 22 major habitat
types (derived by Sanderson et al. 2008 by combining some
of the eco-region classes mapped by Ricketts et al. 1999). In
assessing geographic status of bison in conservation herds,
we considered three criteria: representation of subspecies
American Bison: Status Survey and Conservation Guidelines 2010 57