Biomedical Engineering Reference
In-Depth Information
sequence as a single instance. A trivial example is chasing,
which usually means one animal flees while another runs
toward it. More complex sequences can also be identified.
Asking whether chasing occurs may seem superfluous, but
asking if chasing while vocalizing is more or less common
than silent chasing allows for a more discrete analysis of the
behavioral interactions.
Sequential analysis depends on one's ability to recog-
nize regularities in the co-occurrence of two behaviors
while collecting pilot data. The alternative, a systematic
analysis of all combinations, may reveal additional
sequences, but the cost and effort may be prohibitive.
may be defensive behavior on the part of a frightened
individual; and some may be caused by abnormal endo-
crine, chemical, or neural stimuli. Identifying abnormali-
ties responsible for heightened levels of aggressive
behavior should be possible, but doing so is often compli-
cated by the “normal” aggressive behavior that socially
housed animals direct toward cage-mates. While aggressive
behavior cannot be eliminated in socially housed
nonhuman primates, if the cause of the behavior is under-
stood, it can be controlled to some extent and made
manageable.
Dominance relationships, once established, order
agonistic exchanges in competitive conflicts, reducing the
duration and intensity of those conflicts. When two indi-
viduals with an established dominance relationship enter
a competitive situation and a conflict is provoked, the first
aggressive signal of the dominant individual is typically
answered by submission from the subordinate individual,
who generally withdraws and lets the dominant individual
use the resource. Only after the dominant individual has
finished does the subordinate individual gain access to the
resource. Such exchanges may seem unfair, but it should be
noted that after the dominant individual is satisfied, it
seldom hordes a resource. As long as a resource is in
abundant supply, dominance merely results in orderly turn-
taking. However, one consequence of note is that reducing
the amount of food provided to socially housed nonhuman
primates to reduce waste in no way modifies the amount
a dominant individual receives or wastes (food is still
superabundant to the dominant individual) but may place
a subordinate animal on a deprivation regimen. Addition-
ally, putting all of a resource in a single location sets the
stage for competitive conflicts and dominance turn-taking,
whereas widely scattered resources tilt the balance toward
scramble competition as animals individually forage in
separate locations.
BEHAVIOR RESEARCH TO COLONY
MANAGEMENT
When managing nonhuman primates in captivity, there is
a constant need to evaluate the relationships between
different animals or between the animals and their envi-
ronment. Data collection should not be random but rather
designed to answer specific questions about the animals or
situations of interest. In the preceding sections, we have
defined concepts and described techniques that should
allow a researcher to collect and analyze data in such a way
as to gain insight into the proximate causes of behavior. The
current section discusses an important area of captive
primate management, aggressive interactions between
animals housed together, as a specific example of how to
apply these techniques. Although the examples below focus
on aggressive behavior, the general principles can be
applied to any behavioral question.
Aggressive Behavior in the Context of
Primate Housing
Without question there are long-term benefits to housing
nonhuman primates together in normal, species-typical
social groups. Any time two or more animals come
together, violent conflict is possible. Two similar individ-
uals with similar needs may both want the same resource
simultaneously when that resource is in limited supply or is
situated such that only one can gain access to it at a time.
The two individuals then compete for access to the resource
either by scramble competition, racing to acquire the
resource first, or by contest competition, where one or both
animals actively attempt to preclude the other's access to
the resource. This attempt may take the form of pushing,
threatening, or actively attacking the rival and attempting to
drive it away.
Of course, some forms of aggressive behavior may be
displaced behavior or behavior redirected toward an
available partner; some aggressive behavior may reflect
irritability, as in pain-induced aggressive behavior; some
Study Design for Aggressive Behavior
Ethogram Development
As discussed above, an ethogram is a set of responses
(behavioral acts) that defines the natural behavior of
a species. There are published ethograms for many
nonhuman primate species, and using one of these helps
ensure that your research findings are generalizable to other
colonies. However, if you cannot find an ethogram that suits
your situation, you can develop your own. An ethogram
should consist of several parts: (1) a physical description of
the response; (2) a designation of whether the response is
recorded as a frequency or duration; and (3) in some cases
a contextual note about when or by whom a response might
be seen. This last part will help new observers learn the
responses.
