Zoos Use New Tricks To Stimulate Animals

Bijal P. Trivedi
National Geographic Today

August 27, 2002

One of the more unusual applications for Calvin Klein's cologne,
Obsession for Men, is at the Bronx Zoo, where it drives the female
cheetahs wild. Scientists discovered this little-known fact while
investigating how to create a more stimulating environment for captive
animals—a science called "animal enrichment."

"Most animals have a highly developed sense of smell, and spend their time in the wild with their nose to the ground to sniff out predators, prey, and also rivals," said Joseph Mahoney, supervisor of mammalogy at the Bronx Zoo, New York, where the cheetahs are housed. But in the zoo—where they are well fed and blissfully safe from natural predators—the animals get bored.

The goal of "enrichment" programs is to keep each animal's environment dynamic—constantly changing objects, odors, and sounds to mimic the physical and mental simulation they would experience in their native habitat.

"Part of the enrichment is the searching and hunting before they are rewarded with a new object or smell or food—they need to work for it. It keeps them stimulated," said Mahoney.

Surprise Element

The key is surprise. Adding an element of the unknown keeps the animals' senses on alert, said Diana Reiss, co-chair of the Wildlife Conservation Society's Animal Enrichment Program that is headquartered at the Bronx Zoo.

The zookeepers surprised the cheetahs with different odors to see which ones they enjoyed. About 19 perfumes later, the CK cologne emerged a clear winner.

"The females [cheetahs] have a very strong preference for Calvin Klein's Obsession," said Mahoney, who has had the pleasure of spraying the logs, and tufts of grasses with the heady mix.

When the cologne is sprayed on a log a female might play for 15 minutes—first seeking out the smell, then rolling, rubbing and pawing the log. She even defends the log against an approaching male by chasing him off, said Mahoney.

The preference for this specific cologne may have something to do with one particular ingredient: musk. Musk is a component of many perfumes and colognes and is also a natural substance that animals exude.

Although squirting perfumes around animal enclosures sounds frivolous, animal enrichment is a formal science. It is about measuring the animals reactions and behavior to new objects.

"We try to measure how much the animal is enjoying a particular new object or scent or food," Reiss said. "We record how an animal responds—exactly what it does and for how long."

This enhances the scientists' understanding of a species and enables them to design more fulfilling environments.

Creative Feeding

The zookeepers' challenge is to "enrich" the environments of all the zoo's residents, not just the cute furry ones.

Even with animals like the poison dart frogs from South America, it is important to keep life interesting. Creative feeding, which encourages natural foraging behavior, is one solution.

Hiding a picnic of crickets inside a coconut which had three holes drilled in it provided a culinary challenge for the amphibians. An army of colorful frogs emerged from the foliage to investigate the chirping coconut with the "alpha" frog leading the charge, just as it would in the wild.

To spice up life for a resident octopus, its prey was hidden in a transparent plastic tube with holes drilled for its probing tentacles. The task of retrieving the prey proved too simple for the octopus, so it was given a jar of fish with a screw-cap lid.

"This animal had never experienced a jar before, let alone one with a screw cap, and within two minutes the octopus had unscrewed the lid," said Reiss, who is also director of the Marine Mammal Research and Conservation Program at WCS's New York Aquarium. Curiously the lid became a coveted item and the octopus hid it from its keepers.

Birds of prey were given euthanized, frozen rats that had been wrapped tightly in grass, paper, and string. "Raptors naturally like to catch and rip their prey apart—giving the birds wrapped foods gives them the opportunity to practice this behavior," said Reiss.

Making Medical Exams Fun

In addition to providing objects and hiding food, some of the enrichment activities also help the keepers care for the animals.

"We trained the monkeys to stand on scales, climb into crates, and to deal with physical exams," said Gina Savastano, the senior keeper at the Bronx Zoo's Monkey House. They have trained the small monkeys, mostly tamarinds, marmosets, and capuchins, to show their hands, feet, stomach, tail, and back at the request of their examiner.

"They love it, they love interacting with us," said Savastano. "Sometimes they wait at the door when they see we are about to enter the enclosure. A lot of times they are so overeager that six might stand on the scale at once. We had to train them to stand at color-coded stations while waiting their turn."

The monkeys also enjoy water fights using juice bottles, which they fill with water and then throw on their peers. Mirrors also provide intrigue as mystified monkeys try to find the monkey inside of the mirror.

Although the zoo enclosures—with their props, scents, and sounds—will never match the variety of stimuli of the animals' home turf, researchers like Reiss anticipate that improving the quality of the life of animals in zoos and aquariums may provide the animals with a bit of the pleasure that they give to zoo-goers.

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