American Bison - Buffalo Field Campaign

2) A tendency to flee if approached too closely, too swiftly, or
too directly;
3) A tendency to drift away if approached slowly and
tangentially;
4) Reduced intensity of response with repeated harmless
encounters.
Implications of bison being attracted by food include:
1) The difficulty of fencing them away from good-quality food;
2) A tendency for bison to seek out the highest-quality
forages in their home ranges;
3) The power of food, when properly managed, to amplify
desired behaviour and reduce undesired behaviour.
Ways in which social cohesion can affect handling include:
1) The strong tendency for social groups to follow the lead
animal’s response;
2) The difficulty of separating cows from their young calves
during processing;
3) The stress and disorientation that accompany disruption of
social groups;
4) The ease of translocating and moving animals if social
groups remain intact.
9.6.2 Fencing
Motivated bison can easily cross or destroy fences generally
effective at constraining cattle. Bison-proof fences can be
expensive, and if not carefully designed, may hinder passage by
other wildlife. Efforts to reduce a bison’s motivation to breach
fences can greatly reduce the costs of fencing required to
contain animals, and reduce adverse effects on other species.
Appropriate fence designs vary with circumstance, and a
detailed discussion is beyond the scope of this chapter. More
detailed recommendations and evaluations should be consulted
before any construction begins (e.g., Butterfield 1990a; 1990b;
Gates 2006). In general, a three-strand barbed-wire fence can
hold bison that have been trained to avoid fences and that are
not strongly motivated to cross the fence. High-tensile wire is
more commonly used to build new bison fences or to reinforce
existing ones. Some prefer net-wire fences, but depending on
design, they can be formidable barriers to other animals that
need passage. Electric fences, high tensile or otherwise, greatly
increase the barrier effect to bison, and also condition them to
avoid fences in general.
The need to allow passage for other wildlife affects fence
design where deer, pronghorn, elk, (or other large ungulates) are
present. High tensile fences with the bottom wire at least 51 cm
(20”) off the ground and the top wire 107-132 cm (42”-52”) off
the ground will constrain bison under most circumstances, while
still permitting deer and pronghorn to pass under the fence and
most elk to jump over the fence (Karhu and Anderson 2003). A
three-wire electric fence with the bottom and top wires 56 cm
(22”) and 107 cm (42”) off the ground, respectively, offered better
passage for deer, pronghorn, and elk than did two- or four-wire
designs (Karhu and Anderson 2003). Gates (2006) provides
additional details and recommendations that vary from those
above (e.g., top wire 152 cm (60”) above ground). Additional
guidance should be obtained to ensure fencing meets the needs
of any specific application.
Factors that can modify the effectiveness of fencing include:
1) Bison density; as density increases, more secure fencing
may be required;
2) Deep snow-pack may require special design
considerations;
3) Damage due to falling trees, big game, vandals, or bison;
4) Attractive food, or other objects, on the other side of a
fence increases bison motivation to breach fences.
Factors that influence the effect of fences on deer, pronghorn, or
elk include (Gates 2006):
1) Nutritional stress; adverse impacts increase during periods
of nutritional stress;
2) Some fence designs (e.g., woven wire) have greater barrier
effects than others;
3) Barrier effects that are only seasonal may not be evident
when fences are built;
4) Poor designs may injure or kill animals or separate mothers
from young;
5) Predators may kill big game more easily by chasing them
against fences.
9.6.3 Corrals, pens, and chutes
Corrals and associated facilities for wild bison need to be more
carefully designed and constructed than similar facilities for
domestic livestock. Bison may not recognise standard fencing
as a barrier. Young calves require special attention because
they may run into solid gates or fences, although fences that
are about 80% solid appear to prevent this (Lammers, personal
communication). Fences and gates, with 30-40 cm (12”-16”)
planks spaced 10 cm (4”) apart, effectively stop bison and
can be easily climbed by wranglers. Open fences near the
working chutes, even those that are very strong, often lead to
injury and mortality. Totally solid fencing can be dangerous for
people working animals from the ground if they need to escape
crowded or charging animals.
Bison handling facilities must accommodate the strong social
hierarchy and aggressive behaviours that bison exhibit.
American Bison: Status Survey and Conservation Guidelines 2010 99