Knowledge‐based enrichment: Development of a novel enrichment device for captive chimpanzees

Abstract

The field of environmental enrichment has grown considerably, but most enrichment is still focused on tasks where highly valued food rewards are directly visible. We designed a device which would instead make use of knowledge states, motivational structure, and physical reasoning skills and could use hidden, low‐quality food items while remaining low in cost. Food items were hidden in small cardboard tubes and placed snugly inside another, larger, tube such that they were difficult to extract and presented a challenging dexterity and physical reasoning task. Rare favored food items were distributed so animals would be rewarded at irregular intervals. The devices were then presented to two groups of chimpanzees (Pan troglodytes) who either had experience extracting food from identical small cardboard tubes or had no such experience. We found that the chimpanzees with no prior experience with the small tubes used the device very little until one individual removed a small tube, revealing the food inside, at which point use time significantly increased. In the knowledgeable group, no change was observed after the first tube retrieval. Individuals in both groups used the devices for over 20 min each on average over a 1‐h observation period, and in both facilities at least one device still contained all inner tubes. Our study suggests that enrichment can make use of animals' prior knowledge, that enrichment devices can thus be layered into one another, and reiterates the importance of considering animals' psychology in designing enrichment.

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

“…Thus, captive chimpanzees typically spend less time foraging than their wild counterparts (Inoue and Shimada 2020 ; Yamanashi and Hayashi 2011 ), and this may be linked to reduced behavioral expression and competence, and heightened negative emotional states (Špinka and Wemelsfelder 2011 ). For these reasons, enrichment activities were employed in several studies with the focus on increasing opportunities for foraging (Baker 1997 ; Bloomsmith et al 1988 ; Maki et al 1989 ; Reinhardt 1993), and included food hidden inside boxes, pipes, tubes or balls (Brooks et al 2021 ; Gronqvist et al 2013 ; Nash et al 2021 ) that could only be extracted by manipulating the objects in a specific manner (e.g., poking, shaking, rotating). The sophistication of a device can be altered to vary the complexity of the problem-solving skills required, but it should provide both manipulative and cognitive stimulation to non-human primates (Dutton et al 2018 ), who usually show an interest in food-associated enrichments and motivation to solve puzzles for food rewards (Cheyne 2009 ; de Rosa et al 2003 ; Shohat et al 2019 ), even when highly valued foods are not used (Brooks et al 2021 ).…”

“…For these reasons, enrichment activities were employed in several studies with the focus on increasing opportunities for foraging (Baker 1997 ; Bloomsmith et al 1988 ; Maki et al 1989 ; Reinhardt 1993), and included food hidden inside boxes, pipes, tubes or balls (Brooks et al 2021 ; Gronqvist et al 2013 ; Nash et al 2021 ) that could only be extracted by manipulating the objects in a specific manner (e.g., poking, shaking, rotating). The sophistication of a device can be altered to vary the complexity of the problem-solving skills required, but it should provide both manipulative and cognitive stimulation to non-human primates (Dutton et al 2018 ), who usually show an interest in food-associated enrichments and motivation to solve puzzles for food rewards (Cheyne 2009 ; de Rosa et al 2003 ; Shohat et al 2019 ), even when highly valued foods are not used (Brooks et al 2021 ). Furthermore, as foraging devices make food more difficult to obtain, primates spend more time on these activities and less time inactive or engaged in abnormal behaviors (Brent and Eichberg 1991 ).…”

“…In general, these activities enhance chimpanzee welfare by increasing species-typical behaviors and decreasing abnormal behaviors and other negative indicators of welfare. Moreover, these tool-use tasks can provide data on learning (Hirata and Celli 2003 ; Hirata and Morimura 2000 ; Paquette 1992 ), tool modification (Hopper et al 2015 ), cognitive flexibility (Hopkins et al 2014 ), physical reasoning (Brooks et al 2021 ) and problem solving (Seed et al 2009 ), or other characteristics such as manual laterality (McGrew and Marchant 1992 ; Sanz et al 2016 ) and dexterity (Bardo et al 2017 ; Osuna-Mascaró et al 2021 ). It seems likely that enrichment devices that promote tool use will provide more cognitive stimulation than those that do not require tools.…”