March 22, 2013
1) Chimpanzees must have the opportunity to live in sufficiently large, complex, multi-male, multi-female social groupings, ideally consisting of at least 7 individuals. Unless dictated by clearly documented medical or social circumstances, no chimpanzee should be required to live alone for extended periods of time. Pairs, trios, and even small groups of 4 to 6 individuals do not provide the social complexity required to meet the social needs of this cognitively advanced species. When chimpanzees need to be housed in groupings that are smaller than ideal for longer than necessary, for example, during routine veterinary examinations or when they are introduced to a new social group, this need should be regularly reviewed and documented by a veterinarian* and a primate behaviorist.
*In this context, the Working Group defines a “veterinarian” as a licensed, graduate veterinarian with demonstrated expertise in the clinical care and welfare of nonhuman primates (preferably chimpanzees) and who is directly responsible for the routine clinical care of the animal(s) in question.
We appreciate the emphasis on enhancing social complexity in captive chimpanzees, but we believe that individual compatibility, social history, and individual temperaments have a strong influence on chimpanzee welfare in addition to group size. Thus we recommend that a) group size be one of several variables taken into account when modifying or creating social groups and b) the lower limit of group size set at three individuals. Small groups are not uncommon in wild chimpanzees. Setting the minimum group size at seven may be overly restrictive for some institutions and may not necessarily benefit the chimpanzees given the criteria we mentioned above. We also suggest that “primate behaviorist” be defined as a professional, experienced individual with several years of experience and a professional degree in a relevant discipline (e.g., Psychology, Anthropology, or Biology)
2) The density of the primary living space of chimpanzees should be at least 1,000 ft2 (93 m2) per individual. Therefore, the minimum outdoor enclosure size for a group of 7 animals should be 7,000 ft2 (651 m2)
We do not support this recommendation. This recommendation would be very costly to implement, since when combined with the first recommendation, it would require a minimum living space of 7000 ft2 per group. While we agree that space can be an important feature of the environment for chimpanzees, there is no scientific evidence available that addresses the need for, or benefits of, the amount of space recommended. Instead, published studies indicate that what is contained within an animal environment is more influential than the size of the environment. For example, Ross et al. (2011) showed that captive chimpanzees were highly selective in their enclosure use and that this, “underscores the importance of the quality of the space over the quantity of the space.” It is also not clear if the 1,000 ft2 per individual refers only to floor space, or if other usable spaces such as platforms, climbers, climbable walls, etc. should also be included. We suggest this recommendation be revised so that chimpanzees are provided with an environment that functions to facilitate species-typical patterns of travel and locomotion, and that that this be a performance standard that does not include a precise enclosure size requirement. In addition, it is not clear why outdoor, geodesic dome-type structures were specifically excluded from acceptable housing. Domes can offer deep substrate, they make climbing and high nesting opportunities (over 20 ft) available for chimpanzees, and can be adjoined to other types of housing to offer a variety of choices to chimpanzees. In addition, many studies show that captive chimpanzees prefer sitting next to mesh walls and corners, which are plentiful in dome housing (Traylor-Holtz and Fritz, 1985; Ross and Lukas, 2006; Ross et al., 2009) We suggest that geodesic domes be deleted from the list of unacceptable housing methods.
3) Chimpanzees must be housed in environments that provide outdoor access year round. They should have access to natural substrates, such as grass, dirt, and mulch, to enhance environmental complexity.
We support this recommendation with qualification, recognizing that outdoor access year-round will be limited in some locations in North America and that access to diverse natural substrates does not guarantee social enrichment and chimpanzee welfare.
4) Chimpanzees should have the opportunity to climb at least 20 ft (6.1 m) vertically. Moreover, their environment must provide enough climbing opportunities and space to allow all members of larger groups to travel, feed, and rest in elevated spaces.
We support this recommendation (but note that there is also a lack of empirical evidence to support the exact height that provides climbing opportunities) This proposal is likely to help promote the welfare of research chimpanzees and is practical to implement. We also suggest that in cases where existing enclosures fall slightly short of this standard, professional judgment be used to determine if chimpanzees would benefit from a small increase in height.
5) Progressive and ethologically appropriate management of chimpanzees must include provision of foraging opportunities and of diets that are varied, nutritious, and challenging to obtain and process.
We support this recommendation. It is likely to help promote the welfare of research chimpanzees, is practical to implement, and is a feature of modern chimpanzee management programs in all settings. It is consistent with what we included in our earlier suggestions on defining ethologically-appropriate environments for chimpanzees.
6) Chimpanzees must be provided with materials to construct new nests on a daily basis.
We support this recommendation. It is likely to help promote the welfare of research chimpanzees and is practical to implement. It is consistent with what we included in our earlier suggestions on defining ethologically-appropriate environments for chimpanzees. However, we note that the citation of the Chamove et al., 1982 paper is inappropriate to support the sentence as written, because this paper does not include chimpanzee subjects. In addition, the Baker and Aureli, 1997 paper cited does not deal with substrate or nesting material, thus it is not an appropriate source for this recommendation.
7) The environmental enrichment program developed for chimpanzees must provide relevant opportunities for choice and self-determination.
We suggest that certain types of behavioral research projects involving cognitive testing and providing a variety of novel challenges for chimpanzees are an effective way to offer choice. We encourage the development of a definition of “self-determination” and while we support the view that captive chimpanzees should live in as rich an environment as possible, we note that this recommendation will be difficult to evaluate.
8) Chimpanzee management staff must include experienced and trained behaviorists, animal trainers, and enrichment specialists to foster positive human-animal relationships and provide cognitive stimulation. Given the importance of trainer/animal ratios in maintaining trained behaviors, a chimpanzee population of 50 should have at least 2 dedicated staff members with this type of expertise. Positive reinforcement training is the only acceptable method of modifying behaviors to facilitate animal care and fulfillment of management needs. Training plans should be developed for each animal, and progress toward achieving established benchmarks should be documented.
We support this recommendation with the caveat that some flexibility should be possible in how staffing is organized. This recommendation is likely to help promote the welfare of research chimpanzees. Having behaviorally trained staff will be essential to implement the recommendation related to using only positive reinforcement training methods for animal care and animal management needs. In addition, we feel that there are multiple ways to organize staffing that could achieve the same endpoint of having chimpanzees trained through positive reinforcement methods and having chimpanzee management staff who are experienced enrichment and behavior specialists.
9) All personnel working with chimpanzees must receive training in core institutional values promoting psychological and behavioral well-being of chimpanzees in their care. These institutional core values should be publicly accessible.
We support this recommendation.
10) Chimpanzee records must document detailed individual animal social, physical, behavioral, and psychological requirements and these requirements should be used to design appropriate individualized chimpanzee management in the captive research environment.
We support this recommendation.