Positive reinforcement training to enhance the voluntary movement of group-housed sooty mangabeys (Cercocebus atys atys)

Abstract

Positive reinforcement training (PRT) has successfully been used to train diverse species to execute behaviors helpful in the everyday care and wellbeing of the animals. Because little information is available about training sooty mangabeys (Cercocebus atys atys), we analyzed PRT with a group of 30 adult males as they were trained to shift from 1 side of their enclosure to the other. Over a 4-mo period we conducted 57 training sessions totaling 26.5 h of training and recorded compliance information. During training, compliance increased from 76% of the animals during the first 5 training sessions to 86% of the animals shifting during the last 5 sessions. This result indicated progress but fell short of our goal of 90% compliance. After 25 training sessions, problem-solving techniques were applied to help the consistently noncompliant animals become more proficient. The techniques included reducing social stress by shifting animals so that noncompliant monkeys could shift into an unoccupied space, using more highly preferred foods, and 'jackpot'-sized reinforcement. To determine whether social rank affected training success, animals were categorized into high, medium, and low dominance groups, based on 7 h of behavioral observations. A Kruskal-Wallis test result indicated a significant difference in compliance according to the category of dominance. Although training a group this large proved challenging, the mangabeys cooperated more than 90% of the time during follow-up sessions. The training program improved efficiency in caring for the mangabeys.

Figure 1.

The ethogram used during behavioral observations.

Figure 2.

Percentage compliance of the group of mangabeys during the initial 57 training sessions. The blue diamonds indicate the implementation of problem solving techniques (‘jackpot’ reinforcement, providing additional enrichment, and emptying 1 portion of the enclosure of other monkeys).

Figure 3.

Follow-up percentage compliance for the group; data were collected approximately 34 wk after initial training was completed. There were 2 shifting sessions daily to move the animals from 1 side of the enclosure to the other (indicated as ‘first’ and ‘second’ on the graph). All sessions had greater than 90% compliance.