Group-housing (photos 12-14)

Animate enrichment provides compatible companionship
for the expression of non-injurious social behavior



Photos 12 & 13: Housing nonhuman primates in groups would be the ideal way of social enhancement (photo 12), but there can be serious problems associated with it.
Overt aggressive conflicts are rather common in groups kept in research laboratories (photo 13). Referring to rhesus macaques, Rolland [1991] makes the following observation: "By far the most common physical problem that I treat as a clinical veterinarian is trauma sustained by macaques in group-housing situations. This occurs even when no changes have been made within a previously compatible group [e.g., Reinhardt et al., 1987a; Judge et al., 1994]. The incidence of traumatic injuries is increased when new groups are formed [e.g., Bernstein & Gordon, 1977; Line et al., 1990a; Reinhardt, 1991a; Clarke & Blanchard, 1994; Westergaard et al., 1999] or when animals have to be removed and reintroduced into a group [e.g., Southwick, 1967; Bernstein et al., 1974] for medical reasons, as inevitably occurs. Trauma may range from superficial abrasions to multiple wounds and lacerations, sometimes leading to life-threatening loss of blood and shock." During an eight-month period, "there were 57 injuries requiring removal from group housing and treatment in the clinic in our group-housed, timed mating colony of about 120 females." Mortality caused by fighting may occur at a rate of 10 or even more deaths per 100 group members per year [Kaplan et al., 1980; Kessler et al., 1985].




Photo 14: Are rhesus macaques really so aggressive?

Probably not, because the species thrives in groups under natural living conditions [Southwick et al., 1965; Lindberg, 1971].
It is us who create the problem, by forcing the animals to live in a confined, inadequately structured environment which is bound to provoke conflicts. Moreover, personnel often is lacking the time, the administrative authority - to guarantee optimal group stability - and the knowledge to manage group-housed animals in accordance with ethological principles.


  Adult/infant pairs (photos 15-26)

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