Facilitated Socialization of Previously Singly Caged Adult Macaques

Viktor Reinhardt and Robert Dodsworth
Wisconsin Regional Primate Research Center, 
1223 Capitol Court, Madison, WI 53715

Assuming that non human primates feel better when they have the opportunity to meet their basic needs for social contact and interaction, we have developed two simple and safe methods which permit facilitated socialization of previously singly caged adult animals without interfering with common research protocols (Reinhardt et al. 1987a,b; Reinhardt et al. 1988, 1989; Reinhardt 1988, 1989; Vertein & Reinhardt, 1989).

This video tape depicts several adult rhesus monkeys, each paired with a compatible companion for up to 2 years. Paired partners are not kin-related and with the exception of one case (scene 20) have never lived together.

Scene 1
More than half of all sexually mature caged rhesus monkeys at the Wisconsin Regional Primate Research Center share a cage with one or two compatible 1 to 3.5 years old juvenile companions or with a compatible adult companion. Partner compatibility is independent of sex and age.

Scene 2
13-year-old Simba shares food with 2.5 years old Tito. Like most of the young companions, Tito originates form a breeding troop from which he was removed at the age of 16 months (completely weaned by mother) to avoid overcrowding. Since that time he has been the companion of Simba, who had been individually caged for several years.

Scene 3
12-year old Gentle is sharing food with her 18-month old companion Gina one month after pair formation. Each of the two has a permanent headcap.

Scene 4
11-year old Cilla (with headcap) shares food with her 12-month old (minimum age for pairing with singly caged adult conspecific) companion Cindy on the first day of pair formation.

Food sharing is the most reliable sign for partner compatibility.

Scene 5
7-year-old Mom is too afraid to take food out of the observer's hand. She protectively hugs her 18-month old (maximum age for pairing with singly caged adult conspecific) companion Matt on the first day of pair formation. Matt is comfort-sucking.

Scene 6
18-year-old Flin protectively hugs her 21-month old companion Floh who comfort-sucks. After some hesitation, both take food out of the observer's hand.

Scene 7
7-year-old Daisy and her 21-month old companion Doris daringly take food out of the observer's hand.

Sharing food is the best sign of partner compatibility. 

Scene 8
10-year oid Gretel shares food with her 2-year old companion Gusti.

Scene 9
29-year old Queen shares food with her 3-year old companion BimBim has a headcap for neurophysiological experiments; she became Queen's companion two years ago.

Scene 10 
11-year-old Ella shares food with 3-1/4-year old Elly who has a permanent headcap. Elly has been Ella's companion for tow years.

Note that Elly's headcap is remarkably clean. This is because Ella regularly grooms Elly's head, thereby picking up any crusty material adhering to the implantation site or to the headcap.

Scene 11
14-year old Weaver shares food with her 2-year old companion Wim. Weaver is tethered for an experiment requiring remote blood sampling; Wim has a headcap for neurophysiological experimentation.

Weaver receives an intramuscular injection without being restrained.

Scene 12
14-year old Grunty nurses her baby while sharing food with her 2.5-year old companion Chachu.

Scene 13
29-year old Opa is getting along very well with 3-year old Jack. Both share food. Jack has been Opa's companion for almost two years.

Scene 14 
3-1/4-year old Albert has been the companion of 13-year old Adam for two years.

Albert grooms Adam; he gets Adam involved in a playful chase and wrestle (note the play- faces!) after which he wants to be groomed; he finally is mounted by Adam and groomed by him.

Note the usefulness of the perches and the gnawing wood as species-adequate inanimate objects for environmental enrichment.

Scene 15
14-year old Mike shares food with his 2-3/4-year old companions Max and Gregg.

Scene 16
11-year old Bruce shares food with his 2-3/4-year old companions Bill and Paul.

Scene 17
12-year-old Moon shares food with his 11-year old companion Peter on the first day after pair formation.

Scene 18 
17-year old Ninni and 16-year old Sissi have been companions to each other for two years. They are sharing food, thus showing that they are still compatible partners.

Scene 19
8-year old Cha nurses her baby while sharing food with 7-year old Chip who has been her companion for two years.

Scene 20
12-year old Beta nurses her baby while sharing food with 8-year old Little.

Beta and Little are the only partners who knew each other before they were paired.

Scene 21
7-year-old Salute and 7-year old Sila share food with each other. Both animals have a headcap (note how clean the animals keep each other's headcap!). If one of them is chair-restrained during a neurophysiological experiment, the other is kept close by in a separate cage.

Scene 22
In-home-cage venipuncture of 8-year old Rocky. 11-year old Tora has been Rocky's companion for 1.5 years; she provides psychological support to Tora during the venipuncture.

Scene 23
9-year old Isar and 8-year old Franz are sharing food. Isar solicits Franz .... who mounts him and finally grooms him at length. Franz and Isar are breeding males; they have been companions for six months.

Scene 24
3.5-year old Elly (from Scene 10) is chair-restrained during a neurophysiological experiment. Her partner Ella is kept in a companion cage nearby to provide psychological support. Elly is very calm and takes food out of the experimenter's hand.

Scene 25 and 26 
17-year old Rome and 13-year old Paris provide company for each other. They share food and thus demonstrate good partner compatibility. Rome and Paris have headcaps; when one of them is chair-restrained, the other offers psychological support.

Scene 27
Salute (from Scene 21) is chair-restrained, but her companion Sila is kept close by to offer psychological support. Salute shows no signs of fear and takes food out of the technician's hand.

Scene 28 
Gina (from Scene 3) is chair-restrained. She is not frightened but takes food out of the technician's hand. Gentle (from Scene 3) is kept close by to offer psychological support.

Scene 29 
Pairing previously singly caged animals with compatible companions does not enterfere with a number of common research protocols such as remote blood sampling (Scenes 11 and(D), in-vage venipuncture (Scene 22), implantation of headcaps (Scenes 9, 10, 11, 21, 25).

Scene 30 
12-yearold George and his companions Jimmy and Billy, both 14 months old, sit close to each other during the second night after group formation. There is no sign of social tension. 
Note the usefulness of the gnawing stick and of the perch. 

Scenes 32 
Old friends. Chip & Cha from Scene 19, one year later. 

Scenes 33-36 
Irma and Bluff 2.5 years after pair formation.

Irma appeases Bluff by touching her with extended hand.

Bluff lipsmacks, presents .... is groomed by Irma.

Excitement in room ... Irma and Bluff jump up, cling to ceiling and briefly clasp each other with theighs.

Irma slaps Bluff ... Bluff crouches ... Irma appeasingly touches Bluff.

Scenes 37-38 
Ninni and Sissi 2.5 years after pair formation. The two animals have been exposed to gnawing sticks for two years. 
Ninni gnaws at the stick .... moves out of Sissi's way .... continues gnawing ... drops branch segement ..... Sissi picks it up and starts gnawing. 

Scene 39 
Ninni grooms Sissi for 9 minutes ... Sissi unexpectedly gets up und leaves a baffled Ninni behind. 

Scene 40 
Uta has been Ulla's companion for 2.5 years; she is now 4.5 years old and was successfully bred 4 months ago.

Uta plays with the gnawing stick ... Ulla, who is the dominant one of the two, takes the branch segment out of Uta's hands and starts gnawing.

Unpromptedly, Ulla attentively picks on Uta's fur. Uta seems uninterested, but Ulla gradually gets motivated to groom her young companion. Uta finally shows clear signs that she greately enjoys to be groomed. The grooming session lasts for 16 mintues.

Scene 41 
Opa and Jack (from scene 13) 2.5 years after pair formation The two groom each other - often preceded by mounting -, huddle with each other and gnaw at the branch segment.

Scene 42 
What is possible with rhesus monkeys is also possible with stumptail monkeys: Adult male gently interacts with his little male companion; both groom each other and gnaw at the branch segment.

Scene 43 
Uta (from scene 40) has a 1-week old baby. 
Uta and Ulla are huddling with each other and groom each other reciprocally. 
Ulla grooms Uta's baby.

Why facilitated socialization of previously singly caged primates?

  1. Social animals have a basic NEED for social contact and interaction.
  2. Social animals FEEL BETTER when living with a compatible companion than when living alone.
  3. Representing an EVER-CHANGING, yet PREDICTABLE stimulus, a compatible companion does not lose its BOREDOM-REDUCING value over time.


Reinhardt, V., Cowley, D., Eisele, S., Vertein, R. & Houser, W.D. 1987a. Preliminary comments on pairing unfamiliar female rhesus monkeys for the purpose of environmental enrichment. Laboratory Primate Newsletter, 26(2), 5-8.

Reinhardt, V., Houser, W.D., Eisele, S.G., & Champoux, M. 1987b. Social enrichment of the environment for singly caged adult rhesus monkeys. Zoo Biology, 6, 365-371.

Reinhardt, V., Houser, W.D., Eisele, S.G., Cowley, D. & Vertein, R. 1988. Behavior responses of unrelated rhesus monkey females paired for the purpose of environmental enrichment. American Journal of Primatology, 14, 135-140.

Reinhardt, V. 1988. Preliminary comments on pairing unfamiliar adult males rhesus monkeys for the purpose of environmental enrichment. Laboratory Primate Newsletter, 27(4), 1-3.

Reinhardt, V. 1989. Behavioral responses of unrelated adult male rhesus monkeys familiarized and paired for the purpose of environmental enrichment. American Journal of Primatology, 17, 243-248.

Reinhardt, V., Houser, D. & Eisele, S. 1989. Pairing previously singlv caged rhesus monkeys does not interfere with common research protocols. Laboratory Animal Science, 39, 73-74.

Vertein, R. & Reinhardt, V. 1989. Training female rhesus monkeys to cooperate during in- homecage venipuncture. Laboratory Primate Newsletter, 28(2), 1-3.

Madison, May 1989

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