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Environmental Enrichment For Nonhuman Primates Resource Guide: Social Housing

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Abney, D.M. and J.L. Weed (2006). Methods for successfully pair housing adult male rhesus macaques (Macaca mulatta). American Journal of Primatology 68(Suppl. 1): 59. ISSN: 0275-2565.
DOI: 10.1002/ajp.20270
NAL Call Number: QL737.P9A5
Descriptors: animal behavior, socialization, same sex pairing, pair housing, macaques, Macaca mulatta.
Notes: Meeting Information: 29th Annual Meeting of the American Society of Primatologists, San Antonio, TX, USA; August 16 -19, 2006.

Alexander, S. and M. Fontenot (2003). Isosexual social group formation for environmental enrichment in adult male Macaca mulatta. Contemporary Topics in Laboratory Animal Science 42(4): 122. ISSN: 1060-0558.
NAL Call Number: SF405.5.A23
Descriptors: rhesus macaques, Macaca mulatta, alternative to single housing, self-injurious behavior (SIB), behavioral observations, group formation, rhesus macaques, meeting abstract.

Anonymous (2009). Social housing of nonhuman primates with cranial implants: a discussion. Laboratory Primate Newsletter 48(2): 1-2. ISSN: 0023-6861.
NAL Call Number: SF407.P7 L3
Descriptors: pair housing, nonhuman primates, captive animals, headcap implants.

Augustsson, H. and J. Hau (1999). A simple ethological monitoring system to assess social stress in group-housed laboratory rhesus macaques. Journal of Medical Primatology 28(2): 84-90. ISSN: 0047-2565.
NAL Call Number: QL737.P9J66
Abstract: The increasing awareness of the importance of social housing of laboratory primates results in the establishment of group housing in many facilities. Our aim was to develop a set of manageable tools to allow continuous monitoring of social relations within groups and to establish an objective, scientific ground on which changes in group composition could be based. We studied 38 adult rhesus monkeys (Macaca mulatta) grouped as five one-male/multi-female groups using focal sampling. We recorded the occurrence and direction of aggressive and non-aggressive social interactions as well as time spent inactive in proportion to social contacts, feeding and other activities. The present analysis clearly identified low-ranking animals with none or few affiliative contacts and who also spent much time inactive and separated from other low-ranking animals. This suggests that the present approach results in useful information concerning compatibility between group members and enables identification of animals experiencing high social stress.
Descriptors: primates as laboratory animals, adult rhesus macaques, Macaca mulatta, social behavior, mixed sex groups, monitoring of social relations in group housed animals, levels of aggression, assessing compatibility for social housing, social hierarchy ranking, animal welfare, social isolation.

Baker, K.C., M. Bloomsmith, K. Neu, C. Griffis, B. Oettinger, V. Schoof, A. Clay, and M. Maloney (2008). Benefits of isosexual pairing of rhesus macaques (Macaca mulatta) vary with sex and are limited by protected contact but not by frequent separation. American Journal of Primatology 70(Suppl. 1): 44. ISSN: 0275-2565.
DOI: 10.1002/ajp.20556
NAL Call Number: QL737.P9A5
Abstract: In the issue: Program and Abstracts of the 31st Annual Meeting of the American Society of Primatologists June 18-21, 2008 Guest Editor: Matthew F.S.X. Novak
Descriptors: Macaca mulatta, colony management, group housing, environmental enrichment, meeting abstract.

Baker, K.C., M.A. Bloomsmith, B. Oettinger, K. Neu, C. Griffis, and V.A. Schoof (2014). Comparing options for pair housing rhesus macaques using behavioral welfare measures. American Journal of Primatology 76(1): 30-42. ISSN: 0275-2565.
Online: 10.1002/ajp.22190
Descriptors: full contact pair housing, intermittent contact pair housing, protected contact housing, individual housing, macaques.

Baker, K.C., C.M. Crockett, G.H. Lee, B.C. Oettinger, V. Schoof, and J.P. Thom (2012). Pair housing for female longtailed and rhesus macaques in the laboratory: Behavior in protected contact versus full contact. Journal of Applied Animal Welfare Science 15(2): 126-143. ISSN: 1088-8705.
Online: 10.1080/10888705.2012.658330
Descriptors: pair housing, laboratory animals, longtailed macaques, Macaca fascicularis, rhesus macaques, Macaca mulatta, protected contact housing, full contact housing, adult females.

Baker, K.C., E. Seres, F. Aureli, and F.B. De Waal (2000). Injury risks among chimpanzees in three housing conditions. American Journal of Primatology 51(3): 161-175. ISSN: 0275-2565.
NAL Call Number: QL737.P9A5
Abstract: Meeting the psychological needs of chimpanzees (Pan troglodytes) can be a challenge given their aggressiveness on the one hand and the complexity of their social lives on the other. It is unclear how to balance the need to provide opportunities for species-appropriate behavior against potential risks of injury chimpanzees may inflict on each other. This study evaluates the suggestion that simpler social environments protect chimpanzees from wounding. Over a two-year period all visible injuries to 46 adult males, 64 adult females, and 25 immature chimpanzees were recorded at the Yerkes Regional Primate Research Center. Approximately half of the subjects were mother-reared, and the rest were nursery-reared. Housing included compounds containing about 20 chimpanzees, interconnected indoor-outdoor runs for groups of up to 12 individuals, and smaller indoor-outdoor runs for pairs and trios. Annual wounding rates were calculated for serious wounds (extensive injuries and all those requiring veterinary intervention) as well as for minor wounds. Compound-housed chimpanzees incurred the highest level of minor wounding, but serious wounding levels were not affected by housing condition. Even with a period of dominance instability and elevated levels of wounding in one compound, compound chimpanzees were not injured more than those in smaller social groups over the long term. Nursery-reared females in moderate-sized groups were wounded more than mother-reared females. Also, nursery-reared males and females were wounded less often when paired with mother-reared companions. Overall, this study indicates that maintaining chimpanzees in pairs and trios would not be an effective means for reducing injuries. The management of wounding in chimpanzee colonies is influenced more by the sex and rearing composition of a colony.
Descriptors: animal welfare, three housing situations, comparison study, Pan troglodytes, wounds and injuries, aggression, risk assessment, Yerkes Primate Research Center.

Baker, K.C., M.A. Bloomsmith, B. Oettinger, K. Neu, C. Griffis, V. Schoof, and M. Maloney (2012). Benefits of pair housing are consistent across a diverse population of rhesus macaques. Applied Animal Behaviour Science 137(3-4): 148-156. ISSN: 0168-1591.
DOI: 10.1016/j.applanim.2011.09.010
NAL Call Number: QL750.A6
Descriptors: pair housing, laboratory-housed rhesus macaques, Tulane National Primate Research Center, social behavior, animal welfare, social housing benefits.

Benton, C.G., M.W. West, S.M. Hall, S.T. Marko, and J.C. Johnson (2013). Effect of short-term pair housing of juvenile rhesus macaques (Macaca mulatta) on immunologic parameters. Journal of the American Association for Laboratory Animal Science 52(3): 240-246. ISSN: 1559-6109.
Abstract: Social housing of nonhuman primates (NHP) in an infectious disease setting presents unique challenges, and individual housing is often scientifically justified. At our institute, we recognized an opportunity to limit individual housing to the minimal period necessary by pair-housing NHP after quarantine and separating them just before they are moved into holding rooms for infectious disease studies. To alleviate concerns that pair-housing followed by separation affects the immune system of NHP and makes them unfit as research candidates, we designed a short-term pair-housing study. After a 3-wk baseline period, juvenile rhesus macaques (age, 3 to 4 y) were paired for 7 wk and then separated for 7 wk. During the study, serum cortisol, lymphocyte subsets, and proinflammatory cytokines were measured. The average values for all parameters were significantly lower after separation than during the baseline period. We conclude that short-term pair housing is a viable option at our institute for social housing of NHP.
Descriptors: pair housing, infectious disease research, rhesus macaques, juvenile.

Bloomsmith, M., K. Baker, C. Griffis, B. Oettinger, V. Schoof, A. Clay, and M. Maloney (2008). Behavioral benefits of pair housing in adult rhesus macaques (Macaca mulatta) do not depend on age, previous duration of single housing, or naturalistic rearing. American Journal of Primatology 70(Suppl. 1): 44. ISSN: 0275-2565.
DOI: 10.1002/ajp.20556
NAL Call Number: QL737.P9A5
Descriptors: Macaca mulatta, environmental enrichment, social housing, colony management, single versus group cage, meeting abstract.
Notes: In the issue: Program and Abstracts of the 31st Annual Meeting of the American Society of Primatologists June 18-21, 2008 Guest Editor: Matthew F.S.X. Novak.

Improving the environment of laboratory rhesus monkeys through social interactions and paired housing. Bolderson, A.  Description: This paper provided by the Veterinary Information Portal is a literature review of social housing options for rhesus macaques.

Capitanio, J.P., S.A. Blozis, J. Snarr, A. Steward, and B. McCowan. (2015). Do "birds of a feather flock together" or do "opposites attract"? Behavioral responses and temperament predict success in pairings of rhesus monkeys in a laboratory setting. American Journal of Primatology [Epub ahead of print].
DOI: 10.1002/ajp.22464

Claxton, A.M. (2011). The potential of the human-animal relationship as an environmental enrichment for the welfare of zoo-housed animals. Applied Animal Behaviour Science 133(1-2): 1-10. ISSN: 0168-1591.
DOI: 10.1016/j.applanim.2011.03.002
NAL Call Number: QL750.A6
Descriptors: environmental enrichment strategies, psychological welfare, provision of feeding devices, social housing, novel objects, human-animal relationship (HAR), zoo animals.

De Filippis, B., F. Chiarotti, and A. Vitale (2009). Severe intragroup aggressions in captive common marmosets (Callithrix jacchus). Journal of Applied Animal Welfare Science 12(3): 214-222. ISSN: 1088-8705.
NAL Call Number: HV4701.J68
Descriptors: social housing, marmosets, Callithrix jacchus, aggressive behavior.

DiVincenti Jr, L. and J.D. Wyatt (2011). Pair housing of macaques in research facilities: A science-based review of benefits and risks. Journal of the American Association for Laboratory Animal Science 50(6): 856-863.
Abstract: Despite the enactment in the early 1990s of regulations requiring social housing of nonhuman primates (NHP), single housing is still prevalent in American research facilities. The publication of the 2011 edition of The Guide for the Care and Use of Laboratory Animals has increased emphasis on the implementation of social housing as the default housing method for NHP. Overestimation of the risks inherent in social housing coupled with underestimation of both the benefits of social housing and the risks inherent in long-term single housing has prevented large-scale transitions to social housing. Available caging and housing space often requires research facilities to use isosexual pairs to accomplish social housing. Pair housing presents unique challenges but can be used safely with a thorough understanding of macaque ethology. Here we review literature on the risks and benefits of pair housing macaques in research facilities and provide a concise best-practice approach to pair housing.
Descriptors: pair housing, macaques, laboratory animal research.

DiVincenti, L., A. Rehrig, and J. Wyatt (2012). Interspecies pair housing of macaques in a research facility. Laboratory Animals: 1-3. ISSN: 1758-1117.
Online: 10.1258/la.2011.011134
Descriptors: social housing, nonhuman primates, pair housing, mixed species, cynomolgus macaque, rhesus macaque.

Doyle, L.A., K.C. Baker, and L.D. Cox (2008). Physiological and behavioral effects of social introduction on adult male rhesus macaques. American Journal of Primatology 70(6): 542-550. ISSN: 1098-2345.
DOI: 10.1002/ajp.20526
NAL Call Number: QL737.P9A5
Descriptors: rhesus monkeys, pair housing, process of social introductions, effects on behavior, stress, biotelemetry devices, heart rate, fecal cortisol, adult males.

Egeler, J., S. Hoekwater, and H. Hoffman (2010). A novel approach for utilizing large group-housing style cages for nonhuman primates in toxicology studies. Journal of the American Association for Laboratory Animal Science 49(5): 716. ISSN: 1559-6109.
Descriptors: environmental enrichment, species specific behavior, socialization, toxicology research, vertical flight, group housing.
Notes: Meeting Information: AALAS National Meeting, Atlanta, GA, USA; 2010.

Farmer, H.L., A.B. Plowman, and L.A. Leaver (2011-). Role of vocalisations and social housing in breeding in captive howler monkeys (Alouatta caraya). Applied Animal Behaviour Science 134(3-4): 177-183. ISSN: 0168-1591.
DOI: 10.1016/j.applanim.2011.07.005
Descriptors: black and gold howler monkeys, captive animals, howling vocalization, European zoos, family groups, pair housing, effects of social organization and vocalizations on reproductive success.

Franz, C., S. Macherhammer, E. Kalcher, K. Crailsheim, and S. Preuschoft (2003). The influence of housing conditions on the performance of aberrant behaviours in former laboratory chimpanzees (Pan troglodytes): Association with social interactions. Folia Primatologica 74(4): 194. ISSN: 0015-5713.
NAL Call Number: QL737.P9F6
Descriptors: captive primates, abnormal behavior, chimpanzees, Safaripark Ganserndorf, Austria, group housing effects, social behavior.
Notes: In the Special Issue: Abstracts from the 8th Congress of the German Primate Society, October 1-4, 2003, Leipzig, Germany.

Gaspari, F., G. Perretta, and G. Schino (2000). Effects of different housing systems on the behaviour of the common marmoset (Callithrix jacchus). Folia Primatologica 71(4): 291. ISSN: 0015-5713.
NAL Call Number: QL737.P9F6
Descriptors: housing conditions, environmental enrichment, animal behavior, well-being evaluation, family groups, cage size, cage furniture, effects on play and exploration, Callithrix jacchus, marmosets, meeting abstract.
Notes: Meeting Information: 13th Meeting of the Italian Primatological Society, Pavia, Italy; September 17-19, 1998.

Gilbert, M.H. and K.C. Baker (2011-). Social buffering in adult male rhesus macaques (Macaca mulatta): Effects of stressful events in single vs. pair housing. Journal of Medical Primatology 40(2): 71-78. ISSN: 1600-0684.
DOI: 10.1111/j.1600-0684.2010.00447.x
Descriptors: long-term pair housing effects, stress and anxiety, rhesus macaques.

Ha, J.C., R.L. Robinette, and G.P. Sackett (1999). Social housing and pregnancy outcome in captive pigtailed macaques. Am J Primatol 47(2): 153-163. ISSN: 0275-2565 (Print). 0275-2565 (Linking).
Abstract: We present a retrospective analysis of 30 years of breeding records from a colony of pigtailed macaques at the University of Washington's Regional Primate Research Center, specifically examining the effects on pregnancy outcome of sire presence, presence of other pregnant females, group stability, overall group size, and dam age and parity. Data on 2,040 pregnancies (1,890 live births) of socially housed pigtailed macaques (Macaca nemestrina) were obtained from the Washington Regional Primate Research Center's animal colony records from 1967 to 1996. Our results suggest that the presence of the sire and other pregnant females, fewer moves, and lower parity increases the probability of a viable birth. In viable and nonviable births, gestation length was positively related to contact with the sire and other pregnant females, number of moves, and dam age. Once the effect of gestational age was taken into account, birthweight increased with increasing parity and decreased with dam age. Clinical treatment of the dam decreased as sire presence and group size increased and number of moves decreased. The length of treatment was dependent on the number of moves experienced by the dam, with more moves associated with longer treatments. Sire presence was the single most important factor in nearly all measures of reproductive outcome.
Descriptors: animal housing, Macaca nemestrina, social housing.

Hannibal, D.L., E. Bliss-Moreau, J. Vandeleest, B. McCowan, and J. Capitanio (2016). Laboratory rhesus macaque social housing and social changes: Implications for research. American Journal of Primatology. (Epub ahead of print)
DOI: 10.1002/ajp.22528

Hartner, M., J. Hall, J. Penderghest, and L.P. Clark (2001). Group housing subadult male cynomolgus macaques in a pharmaceutical environment. Lab Animal 30(8): 53-57. ISSN: 0093-7355.
NAL Call Number: QL55.A1L33
Abstract: The authors describe the preliminary results of a program to group-house male cynomolgus monkeys. Using a unique cage design, they were able to achieve environmental enhancement and enrichment that led to easier handling of the animals used in protocols for pharmacological research.
Descriptors: group housing, social environment, Macaca fascicularis, male long-tailed macaques, cage design to facilitate animal handling, environmental enrichment, pharmocological research protocol, animal well-being.

Hotchkiss, C.E. and M.G. Paule (2003). Effect of pair-housing on operant behavior task performance by rhesus monkeys. Contemporary Topics in Laboratory Animal Science 42(4): 38-41. ISSN: 1060-0558.
NAL Call Number: SF405.5.A23
Abstract: This study evaluated the effects of pair-housing on several operant (trained) behaviors in rhesus macaques (Macaca mulatta). Sixteen young, male, individually housed rhesus monkeys (age, 2.5 to 5.5 years) performed a battery of behaviors consisting of motivation (progressive ratio, PR), short-term memory and attention (delayed matching-to-sample, DMTS), color and position discrimination (conditioned position responding, CPR), and learning (incremental repeated acquisition, IRA) tasks. Behavioral assessments occurred 5 days/week, with the PR, IRA, and CPR tasks presented on one test day, and the DMTS task presented on the next test day. Thus, each task was performed two or three days/week. Eight subjects then were pair-housed, while eight age-matched controls remained individually housed. Pair-housed monkeys were separated for behavior testing and feeding but allowed access to each other approximately 20 h/day. The performance of the two groups of monkeys were compared for the 2 months prior to pairing, for a 2-month transition period as the pairs adjusted to the new housing situation, and for a 2-month period after the pairs had been established. Performance of the CPR and IRA tasks did not change over time in either group. For the PR and DMTS tasks, the number of trials completed increased over the course of the study in the controls but not in the pair-housed monkeys. In conclusion, pair-housing monkeys is feasible for studies involving operant behavior testing as a model for a variety of complex brain functions. However, housing condition may affect some test parameters, and this must be taken into consideration during experimental design.
Descriptors: juvenile male rhesus macaques, Macaca mulatta, effects of single housing versus pair housing on tasks, operant conditioning, learning, short-term memory, experimental design for studies of operant behavior.

Jennings, M. and M. Prescott (2009). Refinements in husbandry, care and common procedures for non-human primates: Ninth report of the BVAAWF/FRAME/RSPCA/UFAW Joint Working Group on Refinement. Laboratory Animals 43(Suppl. 1): S1:1-S1:47.
DOI: 10.1258/la.2008.007143
NAL Call Number: QL55.A1L3
Descriptors: refinement alternatives, husbandry, nonhuman primates, housing, restraint procedures, environmental enrichment, social housing, animal well-being.

Jorgensen, M.J., K.R. Lambert, S.D. Breaux, K.C. Baker, B.M. Snively, and J.L. Weed (2015). Pair housing of Vervets/African green monkeys for biomedical research. American Journal of Primatology [Epub ahead of print].
DOI: 10.1002/ajp.22501

Kaiser, R.A., S.D. Tichenor, D.E. Regalia, K. York, and H.H. Holzgrefe (2015). Telemetric assessment of social and single housing: Evaluation of electrocardiographic intervals in jacketed cynomolgus monkeys. Journal of Pharmacological and Toxicological Methods. In press.
DOI: 10.1016/j.vascn.2015.05.001
Descriptors: jackets, cynos, adolescent animals, comparing pair to individual housing, telemetry, equipment damage, dosing, blood collection

Lee, G.H., J.P. Thom, K.L. Chu, and C.M. Crockett (2012). Comparing the relative benefits of grooming-contact and full-contact pairing for laboratory-housed adult female Macaca fascicularis. Applied Animal Behaviour Science 137(3-4): 157-165. ISSN: 0168-1591.
DOI: 10.1016/j.applanim.2011.08.013
NAL Call Number: QL750.A6
Descriptors: abnormal behavior, environmental enrichment, laboratory-housed macaques, pair housing, social housing, long-tailed macaques, grooming bars.

Leonardi, R., H.M. Buchanan-Smith, V. Dufour, C. MacDonald, and A. Whiten (2010). Living together: behavior and welfare in single and mixed species groups of capuchin (Cebus apella) and squirrel monkeys (Saimiri sciureus). American Journal of Primatology 72(1): 33-47. ISSN: 0275-2565.
Online: 10.1002/ajp.20748
NAL Call Number: QL737.P9A5
Descriptors: social housing, primates, mixed species exhibits, species-specific behavior, social enrichment, capuchin, Cebus apella, squirrel monkeys, Saimiri sciureus.

Majolo, B., H.M. Buchanan Smith, and K. Morris (2003). Factors affecting the successful pairing of unfamiliar common marmoset (Callithrix jacchus) females: Preliminary results. Animal Welfare 12(3): 327-337. ISSN: 0962-7286.
NAL Call Number: HV4701.A557
Descriptors: Callithrix jacchus, female marmosets, group housing laboratory primates, sexual maturity, aggression, fighting, grooming animal behavior, successful pair housing.

Marks, D., J. Kelly, T. Rice, S. Ames, R. Marr, J. Westfall, J. Lloyd, and C. Torres (2000). Utilizing restraint chair training to prepare primates for social housing. Laboratory Primate Newsletter 39(4): 9. ISSN: 0023-6861.
NAL Call Number: SF407.P7 L3
Descriptors: Papio hamadryas hamadryas, baboons, pole and collar training, behavioral management, juvenile hamadryas baboons, enrichment program, stress, socialization.

McCowan, B. and I. Rommeck (2006). Bioacoustic monitoring of aggression in group-housed rhesus macaques. Journal of Applied Animal Welfare Science 9(4): 261-268. ISSN: 1088-8705.
NAL Call Number: HV4701.J68
Abstract: Many captive primate facilities house rhesus macaques in multimale-multifemale social groups in large enclosures that simulate the natural social and environmental features characteristic of the species, enhancing their reproductive performance as well as their psychological well-being, yet one of the most difficult management problems in socially housed macaques is their propensity for exhibiting spontaneous bouts of deleterious aggression. To address this management problem, an automated bioacoustic monitoring system might be developed that is capable of detecting and forecasting problematic patterns of contact aggression. To evaluate the utility of this approach, this study examined the magnitude of aggression and the co-occurrence of certain vocalization types and aggression in 10 groups of rhesus macaques. The data confirmed aggression as a significant problem in rhesus groups and indicated that certain patterns of vocalizations are indicative of the type or level of aggression. The detection and classification of these vocalization types need further research to eventually design and implement an efficacious bioacoustic system for monitoring aggression in rhesus macaques.
Descriptors: rhesus macaques, social housing, aggressive behavior, captive management techniques, automated bioacoustic monitoring system, vocalizations.

Best practice in the accommodation and care of primates used in scientific procedures. Medical Research Council (MRC).
Description: Made available online by the UK's National Centre for the Replacement, Refinement and Reduction of Animals in Research (NC3Rs), this ethics guide provides information about experimental design, accommodation and environment (including enrichment, social housing and foraging), handling and training, and veterinary care.

Morgan, D., K.A. Grant, O.A. Prioleau, S.H. Nader, J.R. Kaplan, and M.A. Nader (2000). Predictors of social status in cynomolgus monkeys (Macaca fascicularis) after group formation. American Journal of Primatology 52(3): 115-131. ISSN: 0275-2565.
NAL Call Number: QL737.P9A5
Abstract: The purpose of the present study was to determine whether various behavioral and hormonal markers obtained in individually housed monkeys would be predictive of social rank following group housing. Body weight, serum cortisol and testosterone levels, and locomotor activity in an open-field apparatus were examined in 20 experimentally naive male cynomolgus monkeys (Macaca fascicularis) while they were individually housed. It was hypothesized that eventual subordinate monkeys would have higher cortisol levels and increased locomotor activity scores. These monkeys were then placed in social groups of four (five pens of four monkeys), and social rank was determined based on outcomes of dyadic agonistic encounters. Body weight correlated significantly with eventual social rank. In general, the heavier the monkey the higher the social rank. Locomotor activity in an open-field apparatus following administration of a low dose of cocaine (0.01 mg/kg, i.v.), which has been shown to increase CNS dopamine, correlated with eventual social rank such that individually housed monkeys with high levels of locomotion were more likely to become subordinate. Serum cortisol and testosterone levels failed to correlate with eventual social rank. Hypothalamic-pituitary feedback sensitivity and adrenal responsiveness were examined by measuring cortisol levels after administration of dexamethasone and following ACTH challenge. Cortisol responses in these tests were not associated with eventual social rank. These results suggest that, in addition to body weight, the level of reactivity in a novel environment after administration of a low dose of cocaine is a potential trait marker for social rank. This trait is apparently not associated with hormone levels, but may involve other CNS mechanisms.
Descriptors: social rank predicted by behavioral and hormonal markers, male long-tailed macaques, Macaca fasicularis, single housing into small social groups, cortisol levels, locomotor activity scores, effect of body weight on social rank, level of reactivity to novel environments, cocaine administration, aggression, hypothalamic-pituitary feedback sensitivity, adrenal responsiveness.

Niehoff, M.O., M. Bergmann, and G.F. Weinbauer (2010). Effects of social housing of sexually mature male cynomolgus monkeys during general and reproductive toxicity evaluation. Reproductive Toxicology 29(1): 57-67. ISSN: 1873-1708 (Electronic). 0890-6238 (Linking).
DOI: 10.1016/j.reprotox.2009.09.007
Descriptors: social housing, reproductive parameters, body weight, testicular volumes, toxicity studies.

Novak, M.A., A.F. Hamel, B.J. Kelly, A.M. Dettmer, and J.S. Meyer (2012). Stress, the HPA axis, and nonhuman primate well-being: A review. Applied Animal Behaviour Science In Press ISSN: 0168-1591.
DOI: 10.1016/j.applanim.2012.10.012
Descriptors: cortisol, Environmental enrichment, HPA axis, social housing, stress, abnormal behavior.

Olsson, I.A.S. and K. Westlund (2007). More than numbers matter: The effect of social factors on behaviour and welfare of laboratory rodents and non-human primates. Applied Animal Behaviour Science 103(3-4): 229-254. ISSN: 0168-1591.
DOI: 10.1016/j.applanim.2006.05.022
NAL Call Number: QL750.A6
Descriptors: laboratory animals, housing and husbandry, animal behavior, animal welfare, rodents, nonhuman primates, social housing, social instability, housing systems, data interpretation.

Ottesen, J.L., A. Weber, H. Gurtler, and L.F. Mikkelsen (2004). New housing conditions: improving the welfare of experimental animals. Alternatives to Laboratory Animals 32(Suppl. 1B): 397-404. ISSN: 0261-1929.
NAL Call Number: Z7994.L3A5
Abstract: As animal experiments and testing are still a necessary part of the discovery and development of new drugs and do not seem likely to be totally replaced in the foreseeable future, it is important that the care and use of these animals are continuously refined. Since the housing facilities are where most experimental animals spend the major part of their lives, this area should be given special attention to ensure optimal welfare for the animals. in a unique collaboration between a pharmaceutical company and an animal welfare organisation, the housing conditions of mice, rats, guinea-pigs, rabbits and dogs, respectively, were reviewed with focus on the basic needs of the animals. Prototypes for new housing systems satisfying the most important of these basic needs of the animals were developed, with valuable input from international experts with special knowledge of the behaviour of experimental animals. These new housing systems and species-specific, newly introduced socialisation programmes contribute to improved animal welfare and a better occupational health of the animal caretakers. Since these new housing systems are more pleasant and appealing, they may also have the added benefit that they contribute to a broader public acceptance of the use of experimental animals.
Descriptors: animals in laboratories, housing systems, animal testing, socialization programs, drug development in research, public appeal, addressing basic needs of animals.

Reinhardt, V. (1999). Pair-housing overcomes self-biting behavior in macaques. Laboratory Primate Newsletter 38(1): 4-5. ISSN: 0023-6861.
NAL Call Number: SF407.P7 L3
Descriptors: abnormal behavior, self-biting, compatible social housing, effect of prolonged single-housing, reduction in self-injurious behavior (SIB), macaques.

Reinhardt, V. (2005). Implementing housing refinements in a rhesus macaque colony. Contemporary Topics in Laboratory Animal Science 44(3): 76,78,80. ISSN: 1060-0558.
NAL Call Number: SF405.5.A23
Descriptors: laboratory animals, animal use refinement, cage design, group housing, animal stress, training (animals), animal care, restraint of animals, blood sampling.

Reinhardt, V. (2008). Taking Better Care of Monkeys and Apes: Refinement of Housing and Handling Practices for Caged Nonhuman Primates, Animal Welfare Institute: Washington, DC, 137 p. ISBN: 0938414968.
Descriptors: animal training, positive reinforcement, operant conditioning, blood collection, social interaction, distress, well-being, pair housing, environmental enrichment, foraging enrichment, puzzle feeders, animal behavior, laboratory animals, monkeys, apes, visual contact.

Reinhardt, V. and A. Reinhardt (2000). Social enhancement for adult nonhuman primates in research laboratories: A review. Lab Animal 29(1): 34-41. ISSN: 0093-7355.
NAL Call Number: QL55.A1L33
Descriptors: primates as laboratory animals, enrichment, animal housing, aggressive behavior, males, training of animals, laboratory workers, social housing, pair housing, social enrichment, human-animal interactions.

Reinhardt, V. and A. Reinhardt (2008). Environmental Enrichment and Refinement for Nonhuman Primates Kept in Research Laboratories: A Photographic Documentation and Literature Review, 3rd edition, Animal Welfare Institute: Washington, DC, 129 p. ISBN: 978-0-938414-92-6.
Descriptors: primates as laboratory animals, refinement alternatives, environmental enrichment techniques, photographs, housing and handling methods, social housing, wood sticks.

Rennie, A. and H. Buchanan Smith (2006). Refinement of the use of non-human primates in scientific research. II. Housing, husbandry and acquisition. Animal Welfare 15(3): 215-238. ISSN: 0962-7286.
NAL Call Number: HV4701.A557
Descriptors: animal welfare, environmental and social enrichment, housing, husbandry, refinement, transportation of animals.

Roberts, S.J. and M.L. Platt (2005). Effects of isosexual pair-housing on biomedical implants and study participation in male macaques. Contemporary Topics in Laboratory Animal Science 44(5): 13-18. ISSN: 1060-0558.
NAL Call Number: SF405.5.A23
Abstract: Social housing has been shown to contribute to the psychological well-being and physical health of captive primates, and this factor has led to United States Department of Agriculture guidelines requiring facilities to address the social needs of primate species known to live socially in nature as long as doing so does not endanger the animals or interfere with research goals. Although pair-housing is the best way to provide social enrichment, many researchers and facilities are hesitant to implement it, particularly in biomedical research contexts where implanted devices or behavioral performance might be compromised. In order to study the effects of pair-housing on biomedical implants and study participation, we collected data from a group of isosexually pair-housed male macaques (adult and subadult) with 1) cranial and eye implants and 2) controlled access to water as means of motivating subjects to participate in psychophysical studies. Implants, study participation, and weight gain were not adversely affected by pair-housing. Our results support the use of pair-housing as social enrichment for macaques with biomedical implants and controlled access to water.
Descriptors: Macaca mulatta, Macaca fascicularis, primates as laboratory animals, male macaques, psychological well-being, group housing of primates with implanted devices, pair housing as social enrichment, controlled access to water, prostheses and implants, social behavior of primates in captivity, biomedical research environment, environmental enrichment, animal welfare, animal behavior.

Roder, E.L. and P.J.A. Timmermans (2002). Housing and care of monkeys and apes in laboratories: Adaptations allowing essential species-specific behaviour. Laboratory Animals 36(3): 221-242. ISSN: 0023-6772.
NAL Call Number: QL55.A1L3
Abstract: During the last two decades an increasing amount of attention has been paid to the housing and care of monkeys and apes in laboratories, as has been done with the housing and care of other categories of captive animals. The purpose of this review is to develop recommendations for adaptations of housing and care from our knowledge of the daily behavioural activity of monkeys and apes in natural conditions and in enriched laboratory conditions. This review deals mainly with adaptations of daily housing and care with respect to behaviour, and it is restricted to commonly-used species: Callitrichidae (Callitrix jacchus, Saguinus oedipus); Cebidae (Aotus trivirgatus, Saimiri sciureus, Cebus apella); Cercopithecidae (Macaca fascicularis, M. mulatta, M. nemestrina, M. arctoides, Chlorocebus aethiops, Papio hamadryas, P. cynocephalus); Pongidae (Pan troglodytes).
Descriptors: Callitrix jacchus, Saguinus oedipus, Aotus trivirgatus, Saimiri sciureus, Cebus apella, Macaca fascicularis, Macaca mulatta, Macaca nemestrina, Macaca arctoides, Chlorocebus aethiops, Papio hamadryas, Papio cynocephalus, Pan troglodytes, primates as laboratory animals, New World monkeys, chimpanzees, macaques, abnormal behavior, animal welfare, species differences, group size, cage size, perches, foraging, literature reviews, animal use refinement, environmental enrichment.

Schapiro, S.J. (2000). A few new developments in primate housing and husbandry. Scandinavian Journal of Laboratory Animal Science 27(2): 103-110. ISSN: 0901-3393.
Descriptors: primates as laboratory animals, animal husbandry, animal training, animal welfare.

Schapiro, S.J. (2002). Effects of social manipulations and environmental enrichment on behavior and cell mediated immune responses in rhesus macaques. Pharmacology Biochemistry and Behavior 73(1): 271-278. ISSN: 0091-3057.
NAL Call Number: QP901.P4
Abstract: This paper reviews a series of studies that have examined the effects of manipulations to the social and the inanimate environments on the behavior and cell-mediated immune responses of rhesus macaques of various ages living in different settings. In general, enrichment of the inanimate environment with toys, structures, foraging devices, and/or videotapes increased the amount of species-typical behavior expressed by the monkeys, but did not affect their immune responses. Housing monkeys socially, on the other hand, not only resulted in increased time spent in species-typical activities, but also resulted in (1) decreases in time spent in abnormal behavior and (2) changes in a number of immune parameters. Additionally, attempts to directly influence the affiliative interactions of socially housed adult rhesus have resulted in systematic changes in affiliative behavior, although anticipated accompanying systematic alterations to cell-mediated immune responses have yet to be realized. The data suggest that aspects of the physical and social environments influence behavioral and immunological parameters in captive macaques in the absence of other experimental manipulations. As such, these influences need to be appropriately managed and/or controlled in order to minimize potential confounds in experimental designs.
Descriptors: literature review, social environment, enriched housing, Macaca mulatta, foraging devices, animal behavior, toys, videotapes, immune responses, confounding aspects of experimental protocols.

Schapiro, S.J., J.E. Perlman, and B.A. Boudreau (2001). Manipulating the affiliative interactions of group-housed rhesus macaques using positive reinforcement training techniques. American Journal of Primatology 55(3): 137-149. ISSN: 0275-2565.
NAL Call Number: QL737.P9A5
Abstract: Social housing, whether continuous, intermittent, or partial contact, typically provides many captive primates with opportunities to express affiliative behaviors, important components of the species-typical behavioral repertoire. Positive reinforcement training techniques have been successfully employed to shape many behaviors important for achieving primate husbandry goals. The present study was conducted to determine whether positive reinforcement training techniques could also be employed to alter levels of affiliative interactions among group-housed rhesus macaques. Twenty-eight female rhesus were divided into high (n = 14) and low (n = 14) affiliators based on a median split of the amount of time they spent affiliating during the baseline phase of the study. During the subsequent training phase, half of the low affiliators (n = 7) were trained to increase their time spent affiliating, and half of the high affiliators (n = 7) were trained to decrease their time spent affiliating. Trained subjects were observed both during and outside of training sessions. Low affiliators significantly increased the amount of time they spent affiliating, but only during nontraining sessions. High affiliators on the other hand, significantly decreased the amount of time they spent affiliating, but only during training sessions. These data suggest that positive reinforcement techniques can be used to alter the affiliative behavior patterns of group-housed, female rhesus monkeys, although the two subgroups of subjects responded differently to the training process. Low affiliators changed their overall behavioral repertoire, while high affiliators responded to the reinforcement contingencies of training, altering their proximity patterns but not their overall behavior patterns. Thus, positive reinforcement training can be used not only as a means to promote species-typical or beneficial behavior patterns, but also as an important experimental manipulation to facilitate systematic analyses of the effects of psychosocial factors on behavior and potentially even immunology.
Descriptors: Macaca mulatta, female rhesus monkeys, group housing of laboratory primates, animal welfare, positive reinforcement animal training, social behavior, levels of affiliative interactions, promotion of beneficial behavior patterns.

Schapiro, S.J. and B.J. Bernacky (2011). Socialization strategies and disease transmission in captive colonies of nonhuman primates. American Journal of Primatology ISSN: 1098-2345.
DOI: 10.1002/ajp.21001
Descriptors: colony management, disease transmission, social housing strategies, specific pathogen free primate colony.

Seelig, D. (2007). A tail of two monkeys: Social housing for nonhuman primates in the research laboratory setting. Journal of Applied Animal Welfare Science 10(1): 21-30. ISSN: 1088-8705.
NAL Call Number: HV4701.J68
Abstract: Despite great adaptability, most nonhuman primates require regular tactile contact with conspecifics for their psychological well being. By illustrating the inherent value of social contact and by providing clues to the best ways of satisfying this need, behavioral studies are useful in designing social enrichment programs. Although group housing is ideal for most gregarious primates, space constraints and protocol requirements may preclude such environments for macaques housed indoors. Pair housing is an effective and practical alternative. Furthermore, such social experience facilitates integration into future social groups, including those in postresearch retirement facilities. This article references common research protocols that accommodate pair housing and includes scientific recommendations for institutional animal care and use committees (IACUCs) to facilitate providing physical social contact for non-human primates in laboratories.
Descriptors: social contact, social enrichment, behavioral studies, space constraints, protocol requirements, indoor housing, pair housing, IACUCs, macaques.

Seier, J., C. de Villiers, J. van Heerden, and R. Laubscher (2011). The effect of housing and environmental enrichment on stereotyped behavior of adult vervet monkeys (Chlorocebus aethiops). Lab Animal 40(7): 218-224. ISSN: 0093-7355.
Online: 10.1038/laban0711-218
NAL Call Number: QL55.A1L33
Descriptors: vervet monkeys, stereotypic behavior, cage size, cage level, foraging log, exercise cage, social housing.

Seier, J.V., J. Loza, and L. Benjamin (2004). Housing and stereotyped behaviour: Some observations from an indoor colony of vervet monkeys (Chlorocebus aethiops). Folia Primatologica 75(Suppl. 1): 332. ISSN: 0015-5713.
NAL Call Number: QL737.P9F6
Descriptors: stereotypical behavior, vervet monkeys, environmental enrichment, psychological well-being, housing, complex cages.
Notes: Meeting Information: 20th Congress of the International Primatological Society, Turin, Italy, August 22 -28, 2004.

Spratley, M. and K. Cork (2009). Continuous group housing standard for general toxicology studies as a form of environmental enrichment. Journal of the American Association for Laboratory Animal Science 48(5): 600. ISSN: 1559-6109.
NAL Call Number: SF405.3 .A23
Descriptors: social housing, toxicology studies, environmental enrichment, psychological well-being, animal compatibility, species typical behavior.
Notes: 60th National Meeting of the American Association for Laboratory Animal Science, Denver, CO, USA; November 2009.

Stoinski, T.S., N. Czekala, K.E. Lukas, and T.L. Maple (2002). Urinary androgen and corticoid levels in captive, male Western lowland gorillas (Gorilla g. gorilla): Age and social group related differences. American Journal of Primatology 56(2): 73-87. ISSN: 0275-2565.
NAL Call Number: QL737.P9A5
Abstract: Urinary androgen and corticoid levels were measured for 52 captive male Western lowland gorillas to examine age-related variance and potential differences resulting from various social situations. Significant diurnal variation was present in both hormones. Age-related differences in androgens revealed that males experienced two stages of androgen increase and one stage of decrease: increases occurred from juvenile (less than 10 yr of age) to subadult (between 10-13 yr) and subadult to young adult (14-20 yr), whereas decreases occurred from young adult to adult (> 20 yr). Age-related differences in corticoid levels varied depending on the time of day, but morning corticoids were greatest in juvenile males, followed by young adult males. The type of social grouping was associated with differences in corticoid levels, as animals housed socially (in either a heterosexual or all-male group) had similar corticoid levels, whereas solitary males showed greater corticoid levels than their socially-housed counterparts. The increased levels of corticoids in solitary-housed males suggest this management strategy might not be optimal, although more data are needed. Additionally, the significantly greater levels of androgens and corticoids in young adult male gorillas may present management challenges, and thus zoos may need to consider increasing the flexibility of their current management practices with respect to males.
Descriptors: captive male gorillas in zoos, Gorilla gorilla gorilla, social housing, circadian rhythm, stress, age differences, effects of social situation on androgen and corticoid levels, single housing, management strategies.

Tardif, S.D., D.A. Smucny, D.H. Abbott, K. Mansfield, N. Schultz Darken, and M.E. Yamamoto (2003). Reproduction in captive common marmosets (Callithrix jacchus). Comparative Medicine 53(4): 364-368. ISSN: 1532-0820.
NAL Call Number: SF77.C65
Abstract: Though sexual maturation may begin at around one year of age, first successful reproduction of the common marmoset (Callithrix jacchus) is likely to be later, and it is generally recommended that animals not be mated before 1.5 years of age. The average gestation period is estimated to be 143 to 144 days. A crown-rump length measurement taken by use of ultrasonography during the linear, rapid, prenatal growth phase (between approx. days 60 and 95) can be compared against standard growth curves to estimate delivery date to within 3 to 4 days, on average. Marmosets produce more young per delivery than does any other anthropoid primate, and have more variation in litter size. Many long-established colonies report that triplets are the most common litter size, and there is documented association between higher maternal body weight and higher ovulation numbers. Higher litter sizes generally do not generate higher numbers of viable young. Marmosets are unusual among primates in having a postpartum ovulation that typically results in conception and successful delivery; reported median inter-birth intervals range from 154 to 162 days. However, pregnancy losses are quite common; one study of a large breeding colony indicated 50 percent loss between conception and term delivery. The average life span for breeding females is around six years; the range of reported average lifetime number of litters for a breeding pair is 3.45 to 4.0. Our purpose is to provide an overview of reproduction in the common marmoset, including basic reproductive life history, lactation and weaning, social housing requirements, and common problems encountered in the captive breeding of this species. A brief comparison between marmoset and tamarin reproduction also will be provided.
Descriptors: Callithrix jacchus, marmosets, importance of social housing for reproduction, optimal breeding age, gestation period, liter size, growth rate, laboratory animals, lactation, sexual maturity, comparison between marmoset and tamarin reproduction.

Truelove, M.A., A.L. Martin, J.E. Perlman, J.S. Wood, and M.A. Bloomsmith (2015). Pair housing of macaques: A review of partner selection, introduction techniques, monitoring for compatibility, and methods for long-term maintenance of pairs. American Journal of Primatology [Epub ahead of print].
DOI: 10.1002/ajp.22485

Watson, L. (2003). Pair- and singly-housed adult male M. fascicularis' behavioral response to varying video tape subject matter. American Journal of Primatology 60 (Suppl. 1): 83. ISSN: 0275-2565.
NAL Call Number: QL737.P9A5
Descriptors: long-tailed macaques, Macaca fasicularis, behavioral study, nature film, cartoons, video preferences, effect of housing condition, aggression, meeting abstract.
Notes: Meeting Information: 26th Annual Meeting of the American Society of Primatologists, Alberta, Canada; July 29 - August 2, 2003.

Watson, L. (2010). Effectiveness of Perforated Plexiglass Dividers as Social Grooming Devices Between Neighboring, Individually Housed Adult Male Macaca fascicularis. Laboratory Primate Newsletter 49(4): 1-5. ISSN: 0023-6861.
Descriptors: social housing, laboratory-living nonhuman primates, cynomolgus macaques, males, grooming contact bars, caging system modification, individually housed animals.

Weed, J.L., K.J. McCollom, and F.A. Cisar (2000). Methods for socializing unfamiliar primates to provide environmental enrichment and promote psychological well-being. American Journal of Primatology 51(Suppl. 1): 98. ISSN: 0275-2565.
NAL Call Number: QL737.P9A5
Descriptors: social housing, pair housing, age effects, stainless steel or acrylic panels, type of caging, partner selection, meeting abstract.
Notes: Meeting Information: 23rd Annual Meeting of The American Society of Primatologists, Denver, Colorado, USA; June 21-24, 2000.

Weed, J.L., P.O. Wagner, R. Byrum, S. Parrish, M. Knezevich, and D.A. Powell (2003). Treatment of persistent self-injurious behavior in rhesus monkeys through socialization: A preliminary report. Contemporary Topics in Laboratory Animal Science 42(5): 21-23. ISSN: 1060-0558.
NAL Call Number: SF405.5.A23
Abstract: This paper is a retrospective report describing outcomes for six male rhesus monkeys, each with a history of persistent self-injurious behavior (SIB), after their social introduction to female rhesus monkeys. Pairing procedures for five of the six male primates were implemented after surgical vasectomy. One male had previous pairing experience with a female prior to vasectomy resulting in an unplanned pregnancy. This male was re-socialized with his former female partner after surgery. The SIB-related medical histories of the males before and after the pairings are presented. One goal for promoting pair-housing of chronic SIB male monkeys with female monkeys was to determine whether this intervention would function to reduce or eliminate the expression of SIB and thus provide enhanced socialization opportunities for previously singly housed animals.
Descriptors: Macaca mulatta, male rhesus macaques, self-injurious behavior, socialization with females, vasectomy, pair housing conditions, retrospective studies.

West, A.M., M. Carey, W. Wagner, and J. Erwin (2013). Full-contact social housing of non-human primates (Macaca mulatta and Macaca fascicularis) in a biomedical research facility: Initiation and Implementation. American Journal of Primatology 75(Suppl. 1: Program and Abstracts of the 36th Annual Meeting of the American Society of Primatologists June 19–22, 2013): 1-106. ISSN: 0275-2565.
DOI: 10.1002/ajp.22188
Descriptors: meeting abstract.

Westergaard, G.C., M.K. Izard, J.H. Drake, S.J. Suomi, and J.D. Higley (1999). Rhesus macaque (Macaca mulatta) group formation and housing: wounding and reproduction in a specific pathogen free (SPF) colony. American Journal of Primatology 49(4): 339-347. ISSN: 0275-2565.
NAL Call Number: QL737.P9A5
Abstract: In the present report, we examined the effects of group formation strategy and corral design on wounding and reproduction rates in rhesus macaques. Specifically, we examined group formation using a staged strategy, in which small groups of animals were introduced incrementally over a period of weeks, and a rapid formation strategy, in which all animals were introduced in 1 day. We also examined group formation using a divided corral design that facilitated visual and social separation of individuals, and an undivided corral design that did not facilitate visual or social separation. Dependent measures were wounding and reproductive rates over each of the 2 years that followed group formation. Results indicate that incrementally releasing subgroups of animals, and using a corral design that provides for visual and social separation of individuals, are effective strategies for reducing rates of traumatic wounding when forming multimale-multifemale rhesus macaque breeding groups. However, it must be noted that differences in formation strategy and corral design did not lead to higher reproductive rates. We conclude that incrementally releasing animals in hierarchical subgroups, and using a divided vs. undivided housing design, reduced intra-group wounding and associated demands on veterinary and animal management resources following formation of rhesus macaque breeding groups.
Descriptors: Macaca mulatta, rhesus macaques, social behavior, injury, housing environment, breeding groups, group formation using a staged or rapid approach, reduction of wounding during group formation, corral design, effects on reproductive rates.

Whittaker, M. Managing Monkey Behavior: Advancing the Social Management of Old World Monkeys. Active Environments, Inc. Online:
Description: This paper presents a review of social housing and management of old world monkeys in captivity. It also discusses positive reinforcement training.

Williams, L.E., C.S. Coke, and J.L. Weed (2015). Socialization of adult owl monkeys (Aotus sp.) in Captivity. American Journal of Primatology [Epub ahead of print].
DOI: 10.1002/ajp.22521

Williams, L.E., A. Steadman, and B. Kyser (2000). Increased cage size affects Aotus time budgets and partner distances. American Journal of Primatology 51(Suppl. 1): 98. ISSN: 0275-2565.
NAL Call Number: QL737.P9A5
Descriptors: social housing, perches, nest boxes, instantaneous behavior scans, activity budgets, Aotus sp., owl monkeys, meeting abstract.
Notes: Meeting Information: 23rd Annual Meeting of The American Society of Primatologists, Denver, Colorado, USA; June 21-24, 2000.

Wolfensohn, S. (2004). Social housing of large primates: Methodology for refinement of husbandry and management. Alternatives to Laboratory Animals 32(Suppl. 1A): 149-151. ISSN: 0261-1929.
NAL Call Number: Z7994.L3A5
Descriptors: rhesus macaques, video, animal handling, effects of stress on animal behavior, positive reinforcement training, cage construction and set-up, husbandry and management, social housing, personnel safety.

Worlein, J.M., R. Kroeker, G.H. Lee, J.P. Thom, R.U. Bellanca, and C.M. Crockett (2016). Socialization in pigtailed macaques (Macaca nemestrina)American Journal of Primatology [Epub ahead of print].
DOI: 10.1002/ajp.22556