Environmental Enrichment For Captive Chimpanzees
The environment of captive chimpanzees is far different from their natural habitat. The living conditions in captivity often lack sufficient stimulation for them, which can lead to boredom, anxiety, repetitive behavior, and even self-harm. Providing environmental enrichment — means for the animal to express their natural behavior — is essential for allowing chimpanzees to stay physically and psychologically healthy.
However, not all forms of environmental enrichment are made equal. Enrichment objects prove most effective for animal welfare when they match up with biology and behavior. Observing animals’ reactions to enrichment can help identify items that improve their welfare the most. It’s also important to consider chimpanzees’ individual preferences for different objects — not every individual will enjoy the same thing. Therefore, a combination of social and individual contexts must be considered to improve chimpanzees’ well-being in captivity.
Ethograms are inventories of species-specific behaviors and can be used to evaluate the impact of enrichment items on animal well-being in captivity. Unfortunately, many ethograms use vague terms, include unnatural behavior categories, and neglect the social context necessary for a proper assessment — all of which can negatively impact the success of enrichment strategies.
In a recent study, researchers used a technique called video mining to better understand how to ameliorate the environment of captive chimpanzees. Video mining involves closely watching hours of recorded videos to discover specific patterns. Using videos featuring ten captive chimpanzees, recorded between 2011 and 2021 at the Chimpanzee Sanctuary Northwest in Washington State, the researchers evaluated three ethograms measuring different aspects of environmental enrichment.
They also aimed to identify specific behavior patterns and individual preferences in among the chimpanzees. One ethogram focused on enrichment objects and included toys, forage, structural, nesting, and technology categories. Another ethogram listed manipulation behaviors including oral, active tactile, play-on, nest, and examine behaviors. The last ethogram listed the social context of enrichment including solitary, affiliative (together with other chimpanzees), and proximate (alone but with other chimpanzees close by).
Reviewing the video recordings revealed that chimpanzees displayed a particular interest in toys and forage. About 41% of video recordings of enrichment object manipulation involved interaction with these items. In addition, chimpanzees used oral (bringing items to mouth) and active tactile (moving or manipulating objects with their body) behaviors to interact with enrichment objects in over half of the videos. They mainly manipulated objects while being solitary.
Furthermore, the researchers found specific patterns in enrichment manipulation among chimpanzees. For example, chimpanzees often examined technology objects, nested with nesting objects, and played with structural objects such as rope, boxes, and platforms, interactions which were based on social context. For example, forage objects such as vegetables, bamboo, and flowers were linked with lower affiliative context and higher proximate context. This suggests that chimpanzees preferred manipulating forage by themselves with other chimpanzees close by. On the other hand, they preferred to interact with toys using active tactile behavior together with other chimpanzees.
Interestingly, chimpanzees displayed personal preferences for objects and manipulation behavior. They also showed personal differences in the length of time of interaction with objects, frequency of manipulation behaviors, and duration of social context in which they interacted with enrichment items. Surprisingly, some chimpanzees preferred artificial toys, for example, a troll doll, over other types of objects. This implies the importance of evaluating object preferences for chimpanzees’ welfare rather than solely focusing on naturalistic appearances in captivity. These results highlight the need to consider various factors, including individual needs, age, past experiences, sex, and temperament when providing enrichment for captive animals.
Overall, this study showed that ethograms could successfully capture enrichment object use, manipulation behavior, and social context. However, certain interactions were hard to evaluate. For example, sniffing, spitting out, and examining behaviors were particularly challenging to capture with these ethograms. Another limitation of this study is the potential of observer bias. Specifically, some behaviors might be underestimated while others overestimated depending on the person who sampled the videos. These findings may also not be generalizable to other populations of captive chimpanzees.
In conclusion, this study highlighted the importance of providing chimpanzees with a variety of enrichment objects to stimulate various behaviors in different social settings. By doing so caregivers can promote the well-being of captive chimpanzees in sanctuaries. Ethograms that include object, behavior, and social context of enrichment manipulation are essential tools to fully grasp the complex needs of these animals to improve their welfare.
https://doi.org/10.3390/ani12162029