Why do animals in captivity pace

Their Enclosure is too small — Being stressed about being kept in captivity is one thing. Standards vary from country to country, but the mere nature of being in a zoo means their enclosures are too small in my opinion.

Seen in, for example, giraffe, llama, bears and primates. Standing in one place swaying the head and shoulders — even the whole body — from side to side.

Moving the head up and down, or weaving to and fro continuously. Seen in, for example, bears and elephants. Sitting, sometimes hugging the legs, rocking forwards and backwards. Seen in, for example, captive ape species. Self-inflicted physical harm such as biting or chewing tail or leg, or hitting a head against a wall. Grooming to an excessive extent, pulling out hair or feathers, often leaving bald patches, irritated and broken skin. After studying what other zoos have done to decrease their bears' pacing, Lincoln Park officials decided to leave the doors to Lee and Anana's holding area open during the day.

Just giving the polar bears the ability to choose whether to go into the previously closed area made a profound impact, Ross said. Although Lee only went back there briefly each day, his pacing decreased significantly. The zoo's next move was not as successful. Because polar bears spend much of their time in the wild hunting, killing and eating, other zoos had reduced pacing by freezing the polar bears' food in ice or packing it inside containers, making the animals work for their meals.

Lee seemed to enjoy the challenge, but it didn't reduce his pacing. The next major move did. Officials also changed the visitors' underwater viewing area and improved the pool's filtration system. The renovations were completed last winter. The results have been dramatic.

Lee now spends part of his day rooting through the pits, part playing underwater and part swimming menacingly toward the visitors behind the glass, one of his favorite activities. The polar bear's pacing is now down to 16 percent of his day--half what it used to be, but still higher than Ross would like. This winter, the zoo will take more data, trying to determine if any of the decrease is due to seasonal changes.

This may indicate that primates as hibernators are more prevalent than we think. Pacing is an indication of lack of stimulation.

A recent doctoral study found that larger animals, which have a larger home range in the wild, are particularly prone to pacing in captivity, a behavior known as cage stereotypy.