Stereotyping

No, this isn't going to be a "soapbox speech" about racial or gender judgments. This blog is actually about stereotypic animal behavior. What in the world is that, you ask? Stereotypies are repetitive, ritualistic, often invariant behaviors that appear to have no function. Humans with autism, schizoprenia, and other disorders can exhibit stereotypies, such as body rocking or marching in place. Animals, especially captive animals, also demonstrate stereotypies, including pacing, rocking, swimming in circles, excessive sleeping, self-mutilation, and mouthing cage bars.

A video from Born Free Foundation's archives displays

 multiple animals' over-grooming stereotypies

The cause, development, and significance of animal stereotypies are not yet well understood. However, there is a large amount of evidence to suggest that stereotypies result from stress or deprivation in an animal's life, and the stereotypy is that animal's way of coping. Stereotypies are often caused by artificial environments (like a zoo or stable) that do not allow an animal to experience its full range of normal behaviors. Normal animal behaviors are typically governed by negative feedback loops. For example, if a zebra is hungry, it will begin foraging for food. If the zebra eats, this alters the internal cues and reduces the zebra's motivation to forage.  A scientist named Odberg said in 1978, that "there is one common factor to all conditions in which stereotypies develop: frustration. In all situations some tendency is being thwarted, some goal cannot be reached, some homeostasis is disrupted." As a result, stereotypies often indicate poor animal welfare.

In other words, some highly motivated behaviors (consummatory behaviors), like mating, may be impossible for solitary animals, regardless of how much "mate-search" behavior (appetitive behavior) is performed. No matter how many times a solitary, captive male okapi raises his hoof in a courtship display, he will never find a female okapi to mate with. Or sometimes the consummatory behavior, like feeding, may be performed without the appetitive behavior. For example, if a captive zebra is fed in a trough, it doesn't have to utilize any foraging and grazing behaviors, so those behaviors are vented in frustration-related stress as stereotypies without a function.

But why are these behaviors so persistent, even if they harm the animal? Why are the behaviors so unvarying? For example, pacing animals often place their feet in exactly the same spot and turn at exactly the same moment on each pass. Well, the answer is a complicated neurobiological lesson. External stimuli (like temperature) combine with internal stimuli (like hormone levels) and memory, which are processed by the brain's "executive systems" to select learned and instinctual behaviors. Stereotypies can be adaptive if they serve as a coping mechanism, maladaptive if they are normally adaptive responses occurring inappropriately in an abnormal environment, or pathological if they are caused by a nervous system dysfunction. Coping is any behavioral attempt to control a situation, whether successful or unsuccessful. Coping is often a learned response: the effects of performing a behavior often reinforce that behavior, leading to stereotypies. So stereotypies often reinforce themselves by changing chemical pathways in the brain.

Bamboo the Asian elephant carries a boat bumper at
Woodland Park Zoo in Seattle, WA.
Photo courtesy of Pattie Beaven, elephant keeper,
at Woodland Park Zoo.

Environmental enrichment can be a way to mitigate captive animal stereotypies. Larger and more stimulating enclosures allow for more movement and foraging, while object, scent, or food enrichment allows animals to experience new stimuli on a daily basis as they would in the wild. If an animal is investigating a new object or playing with enrichment, it will be too busy to stereotype. For example, about 40% of elephants in zoos display stereotypies, like rocking and weaving. If a captive elephant is presented with a tire or boat bumper that it can toss, stomp, and carry, that elephant has an outlet for natural behaviors, and spends less time stereotyping. Housing social animals with other animals of their species or in a mixed-species exhibit can also be beneficial. For example, housing primates together encourages grooming, mating, courtship, fighting, and playing, and discourages frustration-based stereotypies like rocking.

Snowball (left) and Misty at the Calgary Zoo in 1993

In some extreme cases, medications can be used to eliminate stereotypies. Snowball, a polar bear at the Calgary Zoo, started demonstrating stereotypies when she was 2 years old. Her keepers tried enrichment programs, diet variation, and enclosure redesign, without success. The keepers reasoned that Snowball's stereotypies had become so ingrained, that they actually altered the composition of her brain causing a neurological disorder. Snowball was given experimental doses of Prozac, which eliminated her stereotypies.

Stereotypies are a touchy subject. Entire books have been written on animal stereotyping, and this blog post is just a brief overview. PETA and other animal welfare organizations use stereotypies as justification for shutting down zoos and releasing captive animals. However, zoos have positive conservation and education roles in society. As a zookeeper, stereotypies are not insurmountable barriers to animal captivity, but rather challenging obstacles to providing the animals in my care with fulfilling lives. I approach each day as a keeper thinking, "how can I make my animals' lives better today?"