Functional Analysis and Successful Treatment of a Captive Rhesus Macaque's Disruptive Behavior.

Functional analysis (FA) is a method developed and used by behavior analysts in human clinical settings to identify possible environmental variables that reinforce undesired behavior. FA is increasingly being applied to better understand the behavior of nonhuman animals. When training monkeys in a room with others, disruptive behavior displayed by neighboring monkeys can impede training progress. In the present study, a FA identified possible reinforcers of disruptive behavior (loud shaking of a toy) exhibited frequently (24% duration pre-treatment) by a rhesus macaque (Macaca mulatta) during in-room training sessions. The functional analysis identified that contingent delivery of foods was maintaining the disruptive behavior, with a mean percent duration of 57% in this condition. The implementation of a function-based treatment consisting of continuous access to a preferred food during in-room training sessions successfully decreased disruptive behavior by over 90% as measured during 15 subsequent sessions. This study advances the current literature applying functional analysis to nonhuman primates as a means of determining the reinforcers maintaining aberrant or undesirable behavior and applying effective treatments based on understanding this function.

Contribution of adult sex ratio to trauma and reproductive output in large breeding groups of rhesus macaques (Macaca mulatta).

Maintaining stable breeding groups of rhesus macaques (Macaca mulatta) can be challenging due to the complex social dynamics and despotic nature of the species. Trauma from aggression is a common problem in rhesus colonies and can cause social disruption, strain veterinary and animal management resources, and potentially affect reproduction. Previous research has shown that increasing the number of non-natal adult males in a breeding group can improve group stability, reduce trauma, and increase reproduction. Here, we used mixed-effects regression models to examine the effects of sex ratio and other factors on trauma and reproduction at the Yerkes National Primate Research Center using a historical dataset made up of four large rhesus groups over an eleven-year period (2003-2013). As expected, sex ratio was a significant predictor for both trauma and reproduction. However, group age since formation was a stronger predictor of trauma frequency and the amount of space available was a slightly better predictor of reproduction than sex ratio or trauma. These results indicate that improving sex ratios can be a viable management strategy to reduce trauma and improve reproduction, particularly when it is difficult to manipulate the group compositions and/or their housing situations. Reducing trauma is a primary goal for rhesus breeding colonies, as it directly impacts the monkeys' health and psychological well-being. Such improvements are necessary for the ethical treatment and care of the animals themselves, but also to reduce financial burdens and maintain a healthy colony for research purposes.

Positive reinforcement training as enrichment for singly housed rhesus macaques (Macaca mulatta).

Positive reinforcement training is one component of behavioural management employed to improve psychological well-being. There has been regulatory promotion to compensate for restricted social housing in part by providing human interaction to singly caged primates, implying an efficacy standard for evaluating human interaction. The effect of positive reinforcement training on the behaviour of 61 singly housed laboratory rhesus macaques (Macaca mulatta) was evaluated at two large primate facilities. Training involved body part presentation and basic control behaviours. Baseline data were compared to two treatment phases presented in varying order across individuals, six minutes per week of positive reinforcement training and six minutes per week of unstructured human interaction. While a MANOVA involving behavioural categories and study conditions across study subjects was significant, univariate ANOVAs found no effect of phase within any behavioural category. Categorising subjects according to rearing, housing facility, or baseline levels of abnormal behaviour did not reveal changes in behaviour with positive reinforcement training or human interaction. This study failed to detect, to any degree, the types of behavioural changes documented in the scientific literature to result from pairing singly housed monkeys. Implementing short durations of positive reinforcement training across large numbers of singly housed animals may not be the most effective manner for incorporating positive reinforcement training in the behavioural management of laboratory macaques. Rather, directing efforts toward individuals with specific behavioural, management, clinical, research or therapeutic needs may represent a more fruitful approach to improving psychological well-being with this technique.

The influence of captive adolescent male chimpanzees on wounding: management and welfare implications.

Adolescence, the period lasting from the onset of puberty to the emergence of physical and sexual maturity, is a period of social change for many species including chimpanzees. Several reports have implicitly linked the physiological changes that occur during male chimpanzee adolescence to significant disruption in the social group, which in turn may result in serious agonism and wounding. To assess the association between adolescent males and wounding rates, 38 institutions housing 399 chimpanzees among 59 social groups, recorded all wounds incurred by chimpanzees over a 6-month period. The rate of wounding did not differ between groups with or without adolescent males. Adolescent males received the most wounds, but were no more likely to cause wounds than group members of any other sex-age class. Social groups with multiple adult males experienced lower wounding rates than those with a single adult male. Results indicate that (1) adolescent male chimpanzees may receive, but not inflict, more wounds than chimpanzees in other sex-age classes; and (2) management strategies that support natural social groupings may control and limit group agonism.

Postconflict behavior in captive western lowland gorillas (Gorilla gorilla gorilla).

Postconflict (PC) behaviors, including reconciliation and consolation, have been observed in many primate and several nonprimate species. Using the PC-matched control (MC) method, PC behavior was examined in two groups (n=13) of captive western lowland gorillas, a species for which no conflict resolution data have been published. Analyses of 223 conflicts showed significantly more affiliation between former opponents after a conflict when compared to control periods, indicating reconciliation. Results also showed significantly more affiliation between the victim and a third-party after a conflict, indicating consolation. Both solicited and unsolicited consolation were observed. The majority of the affiliative interactions observed for both reconciliation and consolation were social proximity, which suggests that unlike most nonhuman primates, proximity, rather than physical contact, may be the main mechanism for resolving conflicts in western lowland gorillas. PC behavior was not uniform throughout the groups, but rather varied according to dyad type.

Videotapes as enrichment for captive chimpanzees (Pan troglodytes).

The effectiveness of showing videotapes to captive chimpanzees as an environmental enrichment was quantitatively tested. The responses of 10 subjects (3 adult males and 7 adult females) to videotapes of chimpanzees engaging in a variety of behaviors, to videotapes of other animals and humans, and to television programs were compared. Data collection consisted of 20-minute, continuous sampling tests while various videotapes were shown. A total of 400 tests were conducted. Multivariate analysis of variance was applied to measure differences in the duration of eight categories of behavior across videotapes of varying content. No general behavioral differences in response to the tapes based on sex or housing were revealed. However, with the behavior of monitor-watching analyzed alone, we found that individually housed subjects watched the videotapes more than socially housed subjects. When viewing time was averaged across all videotapes, the chimpanzees watched the monitor a mean of 38.4% of the time available. The chimpanzees' behavior varied significantly only when they were watching the videotapes of various human and chimpanzee activities and not when watching a blank screen. A Pearson's correlation indicated that subjects habituated to repeated presentations of the videotapes, although the effect was small numerically. Although this type of enrichment did not extensively alter behavior, it did occupy a significant portion of the subjects' activity budget; thus, the amount of time spent watching the video stimuli indicated that videotapes may be a useful enrichment for captive chimpanzees. Zoo Biol 19:541-551, 2000. Copyright 2000 Wiley-Liss, Inc.

Behavioral management of specific pathogen-free rhesus macaques: group formation, reproduction, and parental competence.

Breeding colonies of specific pathogen-free (SPF) rhesus macaques were established to eradicate the transmission of Herpesvirus simiae and several retroviruses in this species. Strategies to attain this goal included the combination of large numbers of monkeys into groups, the establishment of small unimale groups, and a program using animals that were temporarily socially restricted. All methods required the establishment of new social groups from unfamiliar animals. In using these methods, we encountered important behavioral questions related to the group formation process, as well as reproductive and parental competence. Age and prior social experience were important determinants of social and parental success. New multimale-multifemale SPF group formations were successful initially and involved the least aggression during the first breeding season when young females and older males were used. Formation of unimale groups was successful, even when males and females were of similar ages. Breeding competence did not seem to be affected by any of the SPF colony management procedures, but animals with restricted early social experience exhibited impaired parental competence when compared with animals with more social experience. Males were more sensitive to the effects of early social restriction than females. A variety of behavioral obstacles will be encountered when attempting to establish an SPF breeding colony by forming groups by use of these methods. Skilled behavioral management is necessary to surmount these obstacles and to achieve satisfactory social integration, reproduction, and parenting.

Mirrors as enrichment for captive chimpanzees (Pan troglodytes).

At many facilities, limitations of the physical environment have reduced the opportunity for captive chimpanzees to live in large, naturalistic social groups. Convex mirrors used to increase visual access of neighboring groups may improve the social environment. This was tested in a study of 28 chimpanzees (Pan troglodytes) group-housed in conventional indoor/outdoor runs. A total of 47.8 hours of behavioral observations were conducted and comparisons made across three conditions: no mirror present, a mirror present with visual access to neighboring conspecifics, or a mirror present with visual access to the neighbors' empty run. When the mirror gave subjects visual access to neighboring animals, facial expressions, sexual, and agonistic behaviors increased, whereas affiliative behavior decreased compared with when no mirror was present. When the mirror gave subjects visual access to a neighbors' empty run, facial expressions and sexual behavior increased compared with when no mirror was present. When the mirror gave subjects visual access to a neighbor's empty run, agonism decreased compared with when a mirror gave subjects visual access to neighboring animals. When subjects had visual access to neighbors, they used the mirror 30% of the total data points; while they had visual access to the neighbors' empty run, they looked during 24% of the total data points. Juveniles' use of the mirror increased over time while adults' use remained stable. Adult males used the mirror less than did the other subjects. These findings indicate that a mirror allowing visual access to neighboring conspecifics has potential as an enrichment device that affects social behavior.

Guidelines for developing and managing an environmental enrichment program for nonhuman primates.

Before implementing an environmental enrichment program for nonhuman primates, several issues should be considered. The assignment of enrichment tasks can be made to caretakers, a dedicated "enrichment technician," volunteers, students or individuals with training in behavioral science. Determining the enrichment techniques to be used must take into account personnel time available; the species, age, sex, and individual histories of the nonhuman primates; and experimental protocols for which animals are being maintained. Identifying the most beneficial way to use the available personnel time must be tailored for each institution. To meet federal regulations, records must be kept of the environmental enhancements available to each nonhuman primate. Good record-keeping will allow appropriate evaluation of the program. This evaluation should involve the animals' responses to the enrichment opportunity, cost and durability of enrichment items, human and nonhuman safety considerations, and personnel required. The well-being of captive nonhuman primates will be most improved if well-informed decisions are made in developing and managing environmental enrichment programs.

Rigid plastic balls as enrichment devices for captive chimpanzees.

The use of rigid, plastic balls as enrichment devices for 16 captive chimpanzees was studied at The University of Texas M.D. Anderson Cancer Center chimpanzee colony. After the subjects were presented with balls, 10 hours of data were collected for each subject using a scan-sampling technique. The mean percentage of ball-use time for all subjects during the study was 7.1%. There was no sex difference in ball use. Age and housing effects were obtained, with younger animals and those housed in more barren environments exhibiting higher levels of ball use. It is concluded that the balls were worthwhile additions to the chimpanzee environments with use stabilizing at a mean of 2.5% of the subjects' time.

Successful feeding enrichment for captive chimpanzees.

An analysis of a feeding enrichment program for captive chimpanzees was completed to determine the effects of that program on the incidence of agonistic and abnormal behaviors by using 41 adult chimpanzees in six social groups. Four feeding enrichment procedures were implemented simultaneously in the experimental phase of this ABA design study. The procedures were planned to elicit time-consuming, noncompetitive feeding, theorizing a consequent reduction in agonism and detrimental abnormal behaviors typically occurring in captive chimpanzees. The 270 hours of data were collected over a 6-month period. A multivariate analysis of variance result supported the hypothesis, as the barrage of feeding enrichment techniques significantly reduced agonism and abnormal behaviors. This study's significance lies in its application of the scientific method to improving the husbandry of captive primates.