A Model Quantitative Assessment Tool for Nonhuman Primate Environmental Enrichment Plans

Abstract

The housing and care of captive nonhuman primates (NHP) typically meets federal regulations and standards as well as guidelines by private accreditation organizations. There is, however, a gap between such policy, common practices, and the findings of a large empirical research literature on the effects of environmental enrichment (EE), particularly with respect to the degree to which different enrichment strategies lead to a demonstrable improvement of the animal's psychological wellbeing. Assessment tools to guide decisions about selection and refinement of EE practices are largely missing and our companion paper offers a theoretically grounded qualitative approach to the categorization and assessment of sensory, motor, and cognitive (SMC) EE strategies. Here, we propose and illustrate a model for quantitative assessment of enrichment practices using a sample of research facility, zoo, and sanctuary NHP environmental enrichment plans (EEP). Our scoring technique provides a means for comparing the efficacy of different strategies across facilities and allows for the selection of priority areas for improvement. Overall, our assessment tool provides a framework that has several advantages. It is inherently flexible. It can be tailored to fit a range of species. It can readily be adapted to accommodate new evidence about a specific EE strategy, or new EE strategies, or both. Because a scientifically valid evidence-based framework drives priority, our method is readily adaptable to different types of facilities and is more likely to lead to longer-term benefits, both in terms of the enhancement of psychological wellbeing of captive NHP, and with respect to the judicious use of limited resources.

Artificial Termite-Fishing Tasks as Enrichment for Sanctuary-Housed Chimpanzees: Behavioral Effects and Impact on Welfare

“…In our study, however, participation did not decrease over time but actually increased across sessions. Even though animal task engagement does not necessarily provide evidence of a positive effect of the task on their welfare, it surely constitutes a basic indicator of enrichment success [25]. Therefore, the fact that participation increased across sessions indicates that chimpanzees found the termite mounds rewarding, but also that they likely required time to habituate to the task and become efficient at extracting the food.…”

“…In order to assess the impact of a particular enrichment strategy, researchers usually monitor their subjects' behavior by comparing the frequency of species-typical behaviors and abnormal/stress-related behaviors in the presence (versus in the absence) of the enrichment [16,23]. To date, a wide range of environmental enrichment strategies has been implemented and evaluated in non-human primates, including enclosure design and size, food novelty, foraging devices, computer-based devices, sensory stimulation or exposure to conspecifics or humans (i.e., social enrichment) [24,25]. Because wild non-human primates usually spend more time foraging or feeding than captive primates, it is not surprising that enrichment activities for captive groups have mainly focused on increasing opportunities for foraging or feeding [26][27][28].…”

“…Finally, besides monitoring changes in typical behavioral patterns in the presence of enrichment devices, other indicators might be used to assess whether enrichment activities are effective at the individual level. When subjects are free to choose whether to engage in enrichment activities, for example, participation (i.e., whether subjects interact with the device or time spent interacting with it) is usually assumed to be a positive indicator of interest or motivation [24,25,54]. However, when enrichment activities are provided in a social setting, other factors might affect subject participation.…”

Effects of Cage Enrichment on Behavior, Welfare and Outcome Variability in Female Mice

“…Such an approach may allow for the identification of relevant resources or combinations of resources necessary for improving the welfare of laboratory housed rodents. It may also lend insight into relevant mental or cognitive capacities underlying species-typical behaviors (e.g., learning, memory, spatial navigation)—permitting for the development of innovative housing solutions that recapitulate the use of these capacities in the laboratory (for review, see Bennett et al, 2018 ; and for examples of evaluation and application, Dutton et al, 2018 ). In the 70s and 80s, such an approach was pursued in a range of farm animals (e.g., laying hens: Fölsch et al, 1983 ; rabbits: Stauffacher, 1992 ; pigs: Stolba and Wood-Gush, 1984 ), resulting in welfare-friendly prototypes of housing conditions, from which practicable solutions were further developed for specific contexts of animal use (e.g., laboratory rabbits: Stauffacher, 1994 ).…”

Cognitive enrichment in a social setting: assessing the use of a novel food maze in sanctuary-housed chimpanzees

“…For this reason, environmental enrichment has become a key component of the management of captive animals (Maple and Perdue 2013 ), as it is considered an important means of improving animal welfare by providing opportunities for physical, affective and cognitive stimulation (Fernández and Martin 2021 ; Hoy et al 2010 ; Mellor 2015 ). The extensive variety of enrichment strategies used in non-human primates includes sensory stimulation (Carter et al 2021 ; Vaglio et al 2021 ), social housing (Chipangura et al 2020 ), motor or manipulative engagement (Costa et al 2018 ), and more recently, cognitive stimulation (Coleman and Novak 2017 ; Dutton et al 2018 ; Lutz and Novak 2005 ), which also includes the use of digital electronic devices (Clark 2017 ; Clark et al 2019 ; Gray et al 2018 ; Grunauer and Walguarnery 2018 ; Kim-McCormack et al 2016 ). In fact, cognitive enrichment has become increasingly popular in zoos, sanctuaries and even farms, where problem-solving opportunities can enhance animal welfare (Clark 2017 ; Meehan and Mench 2007 ).…”