Introduction to the social housing of primates

One of the most important forms of enrichment that can be provided for any captive, gregarious primate species is social housing. Primate social housing can consist of groupings of two to 100 or more members; captive housing composition should be guided by the species’ typical social structure found in the wild. Knowledge of the natural behavior of individual species is crucial in proper captive management of nonhuman primates (see Primate Info Net Factsheets for species-specific information).

The implementation of a social housing program for facilities with nonhuman primates, including laboratories, zoos, and sanctuaries, requires special attention to ensure the successful formation and maintenance of social groups. Social housing should be overseen by individuals with expertise in nonhuman primate behavior as animals housed socially require ongoing monitoring to ensure compatibility and to reduce the possibility of injury or distress. 

Scientific studies have shown that captive primates who are housed socially exhibit higher levels of species-appropriate behavior, lower levels of stress (both behavioral and physiological indices of stress) and, overall, demonstrate well-being that is superior to that of their singly-housed counterparts.

American Society of Primatologists Policy Statement
Social Housing for Nonhuman Primates Used in Biomedical or
Behavioral Research in the United States

Background: The following policy statement was formulated by the ASP Primate Care Committee for the purpose of providing a public document regarding the ASP’s stance on the use of social housing for nonhuman primates used in research. There is considerable scientific literature on the topic of social housing in laboratory primates, and best practices will continue to evolve over time. Therefore, this policy statement does not address specific scientific findings, rather it articulates general principles held by the society. Since there is variation across practices and regulatory requirements internationally, the scope of this policy is on primates in the United States. These guidelines build upon the ASP’s 2001 Policy Statement “Principles for the Ethical Treatment of Non-Human Primates” which states that ASP members “should make use of information on a species’ natural history to improve management and enrich environments, because physical and psychological well-being are essential not only to the health of the animal but also to the validity of the research results.”

Policy Statement: The ASP endorses social housing as the foundation of welfare for captive nonhuman primates who are members of species that live socially in the wild. (We recognize that social housing may not be appropriate for the very few, more solitary primate species.) The position that social housing should be the default housing for nonhuman primates is based upon the scientific literature, which establishes that socially-housed primates demonstrate wellbeing that is superior to that of their singly-housed counterparts, and that introduction of singly housed primates into a compatible social setting improves their welfare by a variety of behavioral and physiological measures. For example, social housing reduces the expression of species-inappropriate behaviors, promotes species-appropriate activities and can buffer individuals from stress. 

This endorsement is consistent with the positions of the United State Department of Agriculture (USDA), the Office of Laboratory Animal Welfare (OLAW), and the Association for Assessment and Accreditation of Laboratory Animal Care International (AAALAC). The USDA Animal Welfare Act regulation 9 CFR 3.81, states that plans for environmental enhancement must “address the social needs of nonhuman primates of species known to exist in social groups in nature” (USDA, 2013, p. 100). Public Health Service Policy (2002) states that, “The living conditions of animals should be appropriate for their species and contribute to their health and comfort” (OLAW, 2002, p. 5). OLAW has articulated its view on nonhuman primate housing in a policy statement affirming that “like all social animals, nonhuman primates should be socially housed”. Furthermore, AAALAC endorses social housing as the default approach, accrediting only those facilities that meet the standards outlined in The Guide for the Care and Use of Laboratory Animals, i.e., “Social animals should be housed in stable pairs or groups of compatible individuals unless they must be housed alone for experimental reasons or because of social incompatibility” (National Research Council, 2011, p. 64).

To this end, implementing a social housing program for laboratory primates requires special attention to overcome challenges and obstacles encountered in a research setting. The ASP concurs with the following statements:

  1. Appropriately implemented social housing should be guided by species-typical social structure, but may also be beneficial in configurations that do not replicate social groupings in the wild. Ideal configurations may not be feasible given the number or age/sex class of research subjects, or because of constraints related to study design, available housing, or clinical condition. However, the form of housing that involves the least restriction to social experience should be employed whenever practical. This practice is in line with the view that increased social and environmental complexity is associated with increased wellbeing. Even social housing for some portions of time or providing a limited degree of social contact should generally be seen as superior to individual housing.
  2. Housing must be guided by the research use of individual nonhuman primates. Institutional Animal Care and Use Committees (IACUCs) play a pivotal role in this process and are charged with ensuring that scientific justifications for restricted social housing are robust and evidence based. Therefore, it is critical that IACUCs have access to the necessary expertise by including on the committee at least one member with advanced training (i.e., Ph.D.-level expertise) in nonhuman primate behavior and management. The composition of social groups and changes in social setting may be determined by the timeline and experimental design of research projects with justification for restricted social contact during certain phases of a research project. In this case, single housing or restricted contact (including part-time social housing, or tactile contact through a barrier which prevents entry into a partner’s enclosure) should be limited to study phases in which scientific justification for the social restriction applies. The implementation of social housing requires close coordination between research personnel and individuals who are responsible for behavioral and clinical management of the primates. 
  3. Formation and maintenance of social groupings can involve risks to animal health and wellbeing, and should be overseen by individuals with expertise in nonhuman primate behavior and awareness of the relevant aspects of a research protocol’s study design. Animals housed socially require ongoing monitoring to ensure compatibility and reduce the possibility of injury or distress, as initial compatibility may not continue over time. For example, social compatibility may be impacted by changes in study procedures, maturation, aging, clinical impacts of the research procedures or environmental factors. However, it is recognized that even experienced personnel may not be able to manage social interactions in such a way as to avoid all conflict or injury among the animals. 
  4. The need for single housing should not be assumed in research involving the application of experimental appliances (e.g., telemetry implants, head caps, eye coils, tethers), the administration of substances exerting psychosocial effects, or use of restricted/controlled diets. Such research has been successfully performed on socially housed subjects. The potential need for single housing or restriction in social housing should be evaluated using available literature, or, where lacking, awareness of practices and outcomes across facilities. 
  5. The AWA exemption from social housing relating to individuals exhibiting ‘vicious or overly aggressive behavior’ or debilitation should not be applied to broad classes of individuals or species unless supported by published literature or other performance outcomes. Objective criteria should be established for deeming individual animals exempt for these reasons.
  6. Anticipated financial constraints or lack of resources such as appropriate caging are not a sufficient reason to fail to provide social housing. Furthermore, when assessing the potential financial impact of social housing, one should realize the impact that the prolonged use of single housing can have on the costs of lifetime care. Single housing may lead to the need for increased behavioral management and veterinary services to address compromised wellbeing, treatment of behavioral abnormalities that may develop, and adverse impact on research if behavioral abnormalities are severe.

References

National Research Council. The Guide for the Care and Use of Laboratory Animals, 2011.

Office of Laboratory Animal Welfare position statement on nonhuman primate housing. Retreived from http://grants.nih.gov/grants/olaw/positionstatement_guide.htm#nonhuman June 2, 2014.

Public Health Service Policy on Humane Care and Use of Laboratory Animals. United States Department of Health and Human Services, Washington, DC, 1986; amended 2002.

U. S. Department of Agriculture. Animal Welfare Act and Animal Welfare Regulations. Section 3.81 – Environmental enhancement to promote psychological well-being. Animal Welfare Act and Animal Welfare Regulations (“Blue Book”) 2013.

There are workshops available that include curriculum regarding social housing techniques and management practices for nonhuman primates. These workshops are not endorsed by the American Society of Primatologists, but they may be useful to those trying to learn more about introduction methodologies and group management.

Annual

Ongoing