Geoscience Reference
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proximity interactions; Macdonald et al. (1987
)
report systematic patterns in
the frequency with which members of a farm cat colony sit adjacent to other
individuals. Among these cats, and among the aforementioned capybaras, the
social status of some low-status individuals is defined by their spatial peripher-
alization. As Martin and Bateson (1993) noted, extra meaning can be given to
such criteria if it can be shown that there is some aspect of synchrony or com-
plementarity between the actions of individuals in each defined group or dyad
relative to outgroup individuals. Clutton-Brock et al. (1982) used a behavior
similarity index to quantify such complementarity. At a broader scale there
may even be physiological synchrony within groups or between clusters of
groups, as within packs of dwarf mongooses (Creel et al. 1991) or between
packs of Ethiopian wolves (Sillero-Zubiri et al. 1998).
Spatially coherent groups can include a variety of types. Brown's (1975)
schema, adapted by Lehner (1996), is useful in that context. It identified five
broad categories of group: kin groups (families and extended families), mating
groups (pairs, harems, leks, and spawning groups), colonial groups (e.g., nest-
ing sea birds), survival groups (groups drawn to each other for reasons of for-
aging, herding, or huddling) and aggregation groups (formed by physical fac-
tors acting on animals to force them into one geographical location).
Although membership of a spatial group is a frugal expression of nonran-
dom associations, a social group should exhibit some persistent convergence of
behavior or unified purpose that results directly from the association and inter-
action of the constituent network of individuals. That is not to say there will
be no competition, antagonism, or discord within the group. It may be
endemic. But to differentiate a social group (e.g., a pride of lions) from an
aggregation (brown bears at a salmon run may be an example), there must be
some element of cooperation (positive interaction) to offset the disharmony.
Some populations of badgers are organized into groups that cohabit within the
same territory, develop social relationships, and include close kin, yet for a
long time there was scant evidence that they accrued any sociological benefit
from their association. However as more has been learned of the social system
of badgers, more potential advantages of social living have been found. These
include winter huddling to conserve energy (Roper 1992), sporadic allo-
parental behavior (Woodroffe 1993), and occasional examples of coalitionary
aid (Stewart 1997). We have even observed young individuals apparently using
the main sett as an information center and trailing older adults to new feeding
grounds after weaning. The important point to emerge was that none of these
advantages appeared sufficient to explain social grouping, particularly because
at the same time disadvantages of group living have been identified (Rogers et
