Genetics and Behavior During Handling, Restraint, and Herding - Genetics and the Behavior of Domestic Animals - page 115

animals find safety in numbers. One aspect of herd behavior often noted is
that the herd is not completely interested in protection of the group. Instead
self-interest is a primary motivator of the individual ( Couzin and Krause,
2003; Hamilton, 1971 ). The selfish herd theory differed from the popular
idea that evolution of such social behavior was based on mutual benefits to
the population. Herd animals, when they fear a predator work to get into the
center of the herd so they are less vulnerable. Genetic factors are responsible
for both species differences in herd behavior, and individual differences in
how the animals react to the presence of predators or people. Domestic herd
animal behavior may be quite different from that of wild herds of the same
or related species. Interestingly, people who work with wildlife have
observed that African herding animals bunch together more tightly than simi-
lar animals in North America. This may be due to more predators such as
lions, hyenas, and cheetahs.
Visual and Auditory Senses
With eyes positioned on the sides of the head, herd animals have a wide visual
field ( Hutson, 1993; Matthews, 1993; Prince, 1977 ). Panoramic vision enables
animals to move together as a herd and constantly scan the surroundings for
predators or other dangers. Grazing animals are dichromate's and do not see
the color red ( Carroll et al., 2007; Jacobs et al., 1998 ). Dichromatic vision
may also provide a greater sensitivity to visual contrast. Research on sheep
and horses demonstrate that their visual system is designed for horizontal
scanning while grazing ( Saslow, 1999; Shinozaki et al., 2010 ). As herd ani-
mals graze on grass with their heads down, elongated horizontal pupils allow
them to scan the horizon for movement (possible predators) much better than
round pupils. In addition, eye preferences for viewing certain stimuli are com-
mon in a wide range of species. The left and right sides of the brain are spe-
cialized to process information in different ways and to control different types
of behavior ( Rogers and Andrew, 2002 ). The left hemisphere (right eye) plays
a role in assessing novelty and the role of the right hemisphere (left eye) in
processing negative emotional responses ( De Boyer Des Roches et al. 2008;
Farmer et al., 2010 ; Robins and Phillips, 2009 ). Sheep that were separated
from a group of sheep had more ear posture changes and a higher percentage
of animals with forward ears than feeding sheep ( Reefman et al., 2009 ).
Basile et al. (2009) found a right-ear, left-hemisphere preference of the audi-
tory response to neighbor versus stranger calls in horses.
When in flight, cattle, deer, and bison all raise their tails. Kiley-
Worthington (1976) suggests that the raised tail serves as a signal of danger
to the rest of the herd. Social signals that trigger fear represent a particular
type of fear-producing stimuli ( Boissy, 1995 ). Research across species high-
lights the critical role of social fear learning, and the neural mechanisms are
beginning to be understood ( Olsson and Phelps, 2007 ).