American Bison - Buffalo Field Campaign

Plate 7.2 Plains bison near the southern extent of their range near Janos, Chihuahua, Mexico. Photo: Rurik List.
populations within their original range and in major habitat types,
and the geographic area occupied by, or potentially available to,
individual conservation herds.
Representation within and outside their original range: A
displaced population of a subspecies within the original range
of another subspecies may occupy habitat otherwise available
for the recovery and conservation of the indigenous form.
Eighty-seven percent of 62 plains bison conservation herds were
located within the original range of plains bison (Figures 7.1 and
7.3). Eight plains bison herds residing in California, northern
British Columbia, and Alaska were distinctly outside plains bison
original range. Those in Alaska and northern British Columbia
occur in the original range of wood bison. Nine of 11 wood
bison herds were within original range. The two wood bison
conservation populations outside the original range include
one free-ranging herd in the Inter-Lake region of Manitoba
(originally the range of plains bison) and a fenced herd in central
Alberta. The latter wood bison population is Canada’s national
conservation breeding herd at Elk Island National Park, which
also supports a separate herd of plains bison.
Representation in major habitat types: Eighteen major habitat
types occur within the original range of plains bison (Figure
7.4). At least one conservation herd is represented in 14 (78%)
of them and 10 (56%) major habitat types hold two or more
conservation herds. At least one wood bison conservation herd
Figure 7.3 Numbers of plains and wood bison populations within and
outside their original range.
58 American Bison: Status Survey and Conservation Guidelines 2010
is represented in four
(57%) of seven major
habitat types in their
original range, and
four habitat types have
two or more herds.
With the exception of
WBNP and the adjacent
SRL bison herds,
geographic separation
or management of other
populations precludes
inter-population
movements.
Available area: The area
available for a herd
represents the potential
for supporting a large
resilient population
and opportunities for
bison to behave as a
“landscape species”,
interacting with spatially
variable resources and a variety of other native species. On
small pastures, bison may be unable to segregate into social
units (mature bulls, maternal and non-maternal herds) or to move
in relation to resource depletion and abundance gradients. In
addition, the larger the area available, the greater the number of
bison that can be supported sustainably. Landscape area is an
important factor in considering the conservation status of bison.
The area of range available to bison conservation herds
was classified into four categories (metric conversions are
approximate): small areas (less than 20 km 2 ; 5,000 acres);
medium areas (more than 20 km 2 and less than 200 km 2 ; more