modate all agreed-upon enrichments and to permit normal postural adjustment.
Animals prefer to observe from above, but there is not necessarily a physiological difference to accompany this.
Periodic access to larger “activity cage” (frequency, duration)
Tactile social contact with conspecifics
Degrees and type of conspecific contact: visual-only, grooming-contact, pair, small group, typical species-specific group, same-sex, opposite sex, ages, full-time, periodic
Age at weaning
Age at first single housing
Proportion of immature developmental stages spent in single housing
Compatible human caregiver versus same species versus “compatible” species; determination of whether human contact can compensate for individual housing
Structured human contact (training) versus simple contact (e.g., providing treats). Training is beneficial but not a substitute for conspecific contact.
Habituation to caretakers, handlers, experimenters can be beneficial, as can consistency in surroundings. A balance is essential.
Discussion points included the observation that some who conduct enrichment programs at their institutions may not be completely trained in the behavior of one or more species for which they are specifying enrichment programs. Enrichment effects are additive, and it is difficult to examine the pieces in isolation. The whole may be greater than the sum of the parts.
The consensus of the group was that when the science is not available, expert opinion should be used. With regard to who has the expertise, participants stated that it depends on who has the most experience with the individual NHP in question. The team approach is crucial when establishing the best/good practices to be implemented under the institutional and experimental constraints at any given location. In summary, a cage size should be used that is sufficient to accomplish appropriate enrichment and species-specific behaviors.