Animals in the nation’s zoos are faring better as more is learned about ways to relieve their distress, according to experts from zoos and universities who met Friday at Chicago’s Brookfield Zoo.
The scientists are gaining a better understanding of how animals feel, and how a toy or training can often reduce the continuous pacing and other repetitive behaviors that are often believed to be signs of distress.
For example, polar bears like to scratch for hidden stores of food, and some big cats prefer to view visitors from a high perch, and male barn swallows could use a tail extension to attract potential mates.
Visitors who observe a pacing cheetah or a polar bear swimming in circles might believe the animals are stressed by confinement, but instead they may be merely expending excess energy or soothing themselves, said experts during interviews at the symposium.
“We humans swim laps, and people take comfort in walking in circles. As long is it not injuring the animals, and not causing them pain, it may not be a sign of poor welfare,” Nadja Wielebnowski of the Chicago Zoological Society told Reuters.
Wielebnowski, who measures stress hormones in zoo animals, is assisting in efforts to reduce stress when animals are moved, exposed to noise or come in close contact with humans.
“Some species do absolutely great in zoos — they get great food, they get it every day, they have great veterinary care. For some species, the zoo trumps the wild,” David Shepherdson of the Oregon Zoo in Portland told Reuters.
However, some species do not fare as well, such as bears, elephants and large cats.
Shepherdson conducted a study of polar bears in the nation’s zoos, and found 50 out of 54 bears exhibited behavioral symptoms indicative of stress, even though there were no elevated levels of corticosteroids, hormones that specify stress.
Shepherdson further discovered that close to half the bears reduced their repetitive behavior when given training or toys that helped them mimic their behavior in the wild. He found, for example, that polar bears that were provided a plastic barrel would crush it, just as they would a seal den in their native Arctic habitat.
Experts are also looking at whether certain species, such as leopards, do not belong in zoos at all because they favor remaining out of sight.
“Essentially, we need to go against the knee-jerk human reaction, which is the view that (zoo animals) need companionship, they need a large enclosure, and that they are only interested in the world visually,” Vicki Melfi of Whitley Wildlife Conservation Trust, told Reuters. Melfi runs Britain’s Paignton Zoo.
She said animals sensitive to sounds might be offered a dark, quiet corner for retreat, whereas other animals more sensitive to smell might have their enclosures disinfected less frequently so as not to wipe out scent markings.
Wielebnowski suggested zoos might consider exercise equipment for animals to expend excess energy.
Wayne Pacelle, president of the Humane Society of the United States, told Reuters that hormone levels alone might not be as effective as simply looking for repetitive or listless behavior.
“You don’t want a shell of an animal on display,” he said.
“Zoos are here to stay and they should make efforts to enrich animals’ lives and they should ask a number of other questions about the suitability of certain species in captivity.”
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