Polar Bears, Zoos, And Repetitive Pacing
Among the various stereotypic behaviors that captive animals show, pacing is one of the most common. Among animals housed in zoos, pacing is widely reported. Many factors lead to pacing, including quality of an animal’s previous and current environment, lack of novel enrichment, or even anticipation of routine care taking activities. Some researchers have noted that pacing and similar stereotypies may be a result of permanent aberrations in the brain “caused by abnormalities in captive environments.” Others describe it as a direct and ongoing reaction to the captive environment. Very few researchers, however, have attempted to develop a precise definition of pacing that clearly differentiates it from regular locomotion. This differentiation is a necessary first step in identifying and preventing its triggers.
In this study, the researchers used high-speed videotape to record the movement of 11 zoo-housed polar bears. They hypothesized that “the two behaviors (pacing and regular locomotion) should differ significantly in regard to the gait components of head height and step cycle duration as well as the variability of these two measurements.” The researchers methodically collected videotape of both “regular” and “repetitive” walking They analyzed the footage for step cycle duration and variance and head height ratio and variance.
Results showed that pacing did indeed vary significantly from regular walking. Interestingly, 10 out of the 11 bears “were recorded pacing exclusively on flat, barren gunite areas of their exhibits, whereas their other locomotion occurred on a variety of substrates.” Other studies have found that pacing is particularly prevalent on gunite; however, further research that controls for substrates is necessary to understand this variable. That said, the results reveal that pacing “is likely not a species-typical behavior, or a behavior characteristic of most wild individuals in a given species and advantageous for their survival and propagation.” In other words, pacing is indicative of an animal who is coping with stress by “disengaging from [its] environment” through repetitive, goal-less behavior.
For many advocates working to eliminate animal captivity in zoos, addressing the causes of pacing – and stereotypies in general – may seem like wasted effort. However, in the meantime it is important to ensure that captive animals experience optimal welfare, and studies like this offer strategies for doing so.