As welfare scientists, one of the ways that we monitor an animal’s welfare is by systematically observing their behavior. To do so, the first step is to develop an ethogram. An ethogram is a list of species-specific behaviors needed for a particular project, along with the definitions for those behaviors. Generally, when assessing or tracking welfare, we include behaviors indicative of good welfare (e.g. positive vocalizations, social play, object play, exploration of the environment), as well as behaviors that may reflect negative welfare. For instance, a behavior indicative of negative welfare can occur in response to a stressor in the environment but can also be due to a variety of other motivations. Therefore, it is important to determine the amount of time an individual spends performing particular behaviors and to identify the motivations of those behaviors.

Recently, Brookfield Zoo Chicago coordinated a large-scale, multi-institutional study to examine chimpanzee welfare. In chimps, behaviors that may reflect negative welfare include repetitive behaviors or abnormal postures/movements. Traditionally, animal welfare scientists have “pooled” or “lumped” behaviors into subcategories. While this simplifies data collection and analysis, this approach can lead to the creation of subcategories that are made up of behaviors that do not generally co-occur, and therefore, may have unique motivations and treatments. Our study examined the co-occurrence of behaviors in 41 adult chimpanzees living in 16 facilities accredited by the Association of Zoos and Aquariums. We discovered that none of the behaviors that had been thought to reflect a negative welfare state were found to statistically occur together. This lack of correlation suggests that these behaviors may have unrelated motivations and thus require unique management strategies. While our project was not designed to determine the causes behind particular behaviors, our findings can help guide researchers moving forward. In future studies of chimps, behaviors that may reflect negative welfare should be scored separately during data collection and not lumped together into a general category. This will allow researchers and animal care professionals to better understand the diverse causes of the behaviors.

So, what are the takeaway messages from this study? Our findings can be extended to other species. In general, specific behaviors should be scored and analyzed separately, unless those behaviors are found to statistically co-occur. When we are able to identify motivations for particular behaviors, animal care professionals can take action. Indeed, we can introduce tailored treatments and interventions to the environment and/or daily routine. Although there is good evidence that we can reduce negative behaviors in chimps by providing cognitive challenges, introducing enrichment, altering feeding schedules, and offering nesting materials, it would be helpful to know which interventions are most effective for reducing/eliminating particular behaviors. For instance, in individually-housed mink, it was found that removing neighboring individuals was the most effective intervention for reducing repetitive wall-scratching, while other negative behaviors were more likely to be abolished by introducing environmental enrichment.
 
Keep in mind, though: behaviors that look negative to us may not solely reflect an individual’s current welfare status. For example, behaviors can also be influenced by genetic factors or social learning. Perhaps a male chimp repeatedly pats himself because he observed his mother exhibiting this behavior for years. Indeed, while visiting Brookfield Zoo Chicago, you may have seen a young gorilla covering their ears with their hands, which is a learned behavior and is not considered a negative behavior or a sign of poor welfare. Ultimately, it is the job of welfare scientists to identify motivations and treatments for behaviors that may reflect negative welfare. Our team will continue to design studies to better understand the behaviors displayed by particular species so that we can apply our findings to individuals residing at Brookfield Zoo Chicago and beyond!
 
Dr. Jessica Whitham
Animal Welfare Biologist
Published March 14, 2025