Forming a Bachelor Group of Long-tailed Macaques

Written by Michelle Reininger and Carol Asvestas 

Wild Animal Orphanage

January of 1998, twenty-nine male Java macaques (Macaca fascicularis) arrived at the Wild Animal Orphanage (WAO). All were adults, with the exception of one juvenile. None of the male's canine had been blunted. Only the juvenile had been vasectomized. (The juvenile had been previously housed with a female. However, upon arrival at WAO, he was highly aggressive towards her and the decision was made to separate them immediately. The female was later integrated into a mixed group of juvenile Javans.)

The animals arrive in the individual squeeze cages in which they had been living and with which they were familiar. The weather in San Antonio was chilly but not freezing; temperatures from the varied from the mid 30's to high 40's. Our first major task was making sure that they adjusted to the climate, as they would be living outdoors for the first time.

The cages were placed in a large, outdoor quarantine area that was completely covered by a roof. The cages were placed side by side, in four separate rows, so that the animals were close. The four sides of the quarantine area were covered with heavy tarps. Blow heaters were kept on hand to use, as needed. Hay was also packed around the cages for additional warmth.

Five of the animals, the oldest in the group, were suffering from chronic diarrhea due to the stress of traveling. These were placed indoors, away from the others, and treated daily. Despite the extra attention, only one of the five survived.

The monkeys stayed in the quarantine area for about one month. During this time, the position of the cages was repeatedly changed. In this way, they got to know each other at one time or another; only minor aggressive behavior was observed.

The monkeys were then moved, still in their single cages, into another large, enclosed outdoor area that was closer to their final destination. This time, they were placed in two rows, side-by-side and back-to-back. This area was next to some large exotic felines. We wanted the macaques to get used to the sounds and smells of big cats, as they will eventually share the same compound. To minimize stress, we covered one side of the area the macaques were in so they could not immediately see the cats.

After two weeks, the covers were removed to allow the macaques to see the big cats. No stress was observed; rather, they seemed to enjoy the new sights and sounds.

After another two weeks, large chimp cages (measuring 5ft X 5ft X 8ft) were placed inside the large, natural area in which they will live. The cages were placed next to one another, in a U-shape, close enough so that the macaques could interact between cages. Each cage was equipped with a tire, chained in the center of the cage. This established two levels within the cage. This would be important in assisting the establishment of hierarchy.

At this point, the staff began the process of determining potential partners. The pairing was determined by the aggressive, or submissive, behavior that was displayed by the monkeys while in the single cages. The monkeys were paired in such a way as to make the establishment of dominance/subordinance relationships easier. Once decided, the subordinate animal was released into the cage first, immediately followed by the dominant.

After being paired in the chimp cages, only minor fighting occurred and rank relationships were immediately established. They remained paired, side-by-side, for approximately nine months. In this time, only one pair had a change in rank relationship. All of the others remained comfortable in their status. In fact, they flourished. Each male's body size increased as his muscle tone improved. Those that had exhibited stereotypic behavior by hair-pulling now occupied their time by grooming their partners. Left on their own, with minimum human involvement, they became stronger and more confident.

In the meantime, a large (40ft X 50ft X 25ft) enclosure was erected to house the entire group. The new area contained numerous large trees and various climbing apparatuses, as well as large rocks and shelter boxes for escape areas. The shelter boxes were placed in separate areas of the cage and were fitted with heating devices to provide warmth, if needed, during the winter.

In order to move the macaques with minimal difficulty and stress, each monkey was given a 1cc dose of ketamine. One by one, they were placed inside the new area. Males who had been paired were placed near one another to provide some familiarity upon recovery from the ketamine.

The process of tranquilizing and moving the 24 macaques took about two hours. Because they were all tranquilized within a relatively short period of time, all began to recover from the effects of the ketamine around the same time. As they became aware of their new surroundings, they began to explore. Their beginning explorations were completely terrestrial. Somewhat groggy, they moved about sniffing trees, eating leaves and playing with the dirt. Everything was a new experience. When encountering another animal, they lip-smacked while clutching one another's shoulders.

The largest male was one of the first to become completely alert. He marched about the enclosure lifting tails and sniffing hindquarters. He devoted the most attention to the male he had been paired with, but didn't stop with him. He made a complete circle of the perimeter, inspecting each monkey in turn.

As the others became more alert, they began to explore higher areas. Each male scaled a tree to the very top, then found a comfortable limb to rest upon. At this point, four of the males began lip-smacking and soliciting the attentions of the largest male. This group would eventually become a "gang" of sorts. They established their rule over the others with a series of attacks and ambushes to assert their dominance. It should be noted, at this point, that despite this aggressive establishment of a hierarchy associated with grouping, injuries were minor. (In fact, the worst injuries were a split lip and a bite on the leg, both of which healed up quickly and cleanly.)

Only one pair remained together after the move. The pair consisted of a 24-year-old male and his former cage-mate, the 5 year-old juvenile. The juvenile had asserted himself as dominant over the 24 year-old in the double cage. When confronted with a group of larger, older males, the juvenile became submissive and clung to the back of his cage-mate as if he were his mother.

This proved to be beneficial to the older male. When challenged by another male, the 24 year-old reciprocated the threat. The juvenile backed him up and the challenging male decided to "seek entertainment" elsewhere. This happened a few more times and then the 24 year-old gained the confidence to initiate his own attacks. His rank within the troop rose rapidly. In fact, he has been accepted by the "gang" and often joins them in disciplining those of lower rank. Having the protection of the older male, the juvenile benefits as well.

The higher-ranking males occupy the front area of the enclosure for most of the day. At feeding time, it is this area that is provisioned first. Also, this area gives a better view of the compound. From here, they can see the activities of other animals and the movements of the staff.

The back area of the enclosure belongs to the lower-ranking members of the troop. This area has many trees and provides more place to hide from unwanted attention. This is also the last area to be provisioned.

Amazingly, the trees have remained relatively undamaged by the macaques. Although the animals repeatedly shake them in displays, they have not stripped them of bark, as has happened with other macaque groups, most notably a large group of stump-tails (Macaca arctoides). In fact, there has been almost no destruction of their new habitat, other than the loss of some leaves and grass, which they consume.

The males now appear comfortable in their new surroundings. they are quite active throughout the day, both in groups and on their own. They enjoy perching in the trees, munching on leaves, or sitting in pairs grooming one another. Occasionally, a few will band together and chase or threaten another. However, this usually ends when the monkey who is the focus of the attack reacts with submissive gestures or somehow interests the attackers in going after another animal. No one has ever been harmed in such an "attack".