Behavioral Effects of an Enhanced Enrichment Program for Group-Housed Sooty Mangabeys (Cercocebus atys).

Evaluating the behavioral effects of enrichment on animals housed in biomedical facilities is necessary to effectively support their care and wellbeing. We tested the cumulative effects of an enhanced enrichment program on sooty mangabey behavior: locomotion, feeding and foraging, manipulating items in the enclosure, social affiliation, aggression, and abnormal behavior. The enhanced enrichment program included the addition of a substrate (timothy hay), widely distributing small pieces of produce and a forage mixture in the hay, adding structures and perching, and increasing the variety of food items, foraging devices, and other manipulable items. We tested 10 groups living in runs (n = 54) by using an ABA experimental design (phase A, standard enrichment; phase B, enhanced enrichment) and Wilcoxon signed-rank tests to compare behavior across phases. During phase B, subjects significantly increased feeding, foraging, and manipulation of items, and they decreased self-grooming, social affiliation, and aggression. Combined enrichment use increased from approximately 10% to 21% of the mangabeys' time. Enhanced enrichment did not affect locomotion or abnormal behavior. The increases in feeding, foraging, and manipulation during enhanced enrichment were driven primarily by the subjects' preference for foraging in the hay: it was the most effective component of the program in promoting feeding and foraging behavior, which comprises the majority of wild sooty mangabeys' daily activity. Developing an effective, species-appropriate, and comprehensive enrichment program is essential to successfully promote the health and wellbeing of captive NHP.

Effects of changing housing conditions on mangabey behavior (Cercocebus atys): Spatial density, housing quality, and novelty effects.

The separate influences of spatial density and housing quality on the behavior of captive animals are difficult to measure because the two factors are often intrinsically linked. Here, we recorded affiliative and agonistic behavior in adult sooty mangabeys in various housing situations, testing spatial density and housing quality changes separately (N = 26 experienced spatial density changes; N = 12 experienced housing quality changes). We varied spatial density by 50% while holding housing quality constant and we varied housing quality while holding spatial density constant (achieved by comparing two types of run-housing that varied in the amount of visual privacy and outdoor access). Each housing condition was one month in duration. Prior to collecting data in each housing condition, we evaluated the subjects' initial responses to the change in housing environment during 2-week novelty periods. Affiliative behavior did not change during the novelty periods. Agonistic behavior initially increased slightly when spatial density increased and it decreased significantly when spatial density decreased; it also decreased when subjects moved to housing that offered more visual privacy and outdoor space, indicating that the mangabeys were sensitive to these housing changes. After the novelty periods, affiliative behavior increased under higher spatial density, but remained unchanged across housing quality conditions; agonistic behavior remained unchanged across all conditions. Results suggest that a prolonged increase in spatial density led the mangabeys to adopt a tension-reduction coping strategy, in which the increase in affiliative behavior alleviates a presumed increase in social tension. Reducing visual privacy and choice did not affect the mangabeys' behavior, post-novelty period. Thus, like many other primates, the mangabeys managed tension by flexibly adapting to changes in their housing environment in ways that reduce the risk of severe aggression. This study highlights the importance of controlled behavioral studies in facilitating data-driven management decisions that promote animal welfare. Am. J. Primatol. 77:1001-1014, 2015. © 2015 Wiley Periodicals, Inc.

Dynamic in-hand movements in adult and young juvenile chimpanzees (Pan troglodytes).

Descriptions of manual function in nonhuman primates have largely focused on static precision and power grasping (as first defined by Napier,1956), while identification and description of dynamic manual function are rare and incomplete. Here, we describe several forms of in-hand movements used by chimpanzees (Pan troglodytes) when manipulating small objects. In-hand movements are defined as the movement of an object within one hand via manipulation of the digits. We presented adult and young juvenile chimpanzees (ages 5-29 years) with a task that required inserting small objects through correspondingly shaped cutouts in a transparent Plexiglas panel. While attempting to insert the objects through the cutouts, the subjects used at least two forms of in-hand movements to change their grip on the object for more precise alignment. We describe in detail the in-hand movements they used and the variability observed in form and execution among the subjects. In general, the adult subjects used in-hand movements more frequently and used a wider variety of forms than did the young juvenile subjects, suggesting that in-hand movements are in the process of fine-tuning around the age of 5 years in chimpanzees. The dexterity exhibited by the adults, however, shows that the neuromuscular and morphological requirements for relatively complex digital manipulation are present in the adult chimpanzee.