Muru Goes to School

A day in the life of Muru might look like this: Target lessons, snack time, swimming, basking, shuffle down the hall, dinner. Muru is a six-year-old Nile crocodile living at the Bronx Zoo’s World of Reptiles. When he first arrived at the zoo from South Africa in May 2008, his days tended to look more like this: Basking, dinner.

Staff at the World of Reptiles recognized Muru’s potential to learn a new routine right away. “I thought he was the coolest crocodile,” said wild animal keeper Lauren Augustine, who keeps a training journal to record Muru’s progress. “He was really responsive.” A former keeper at the Maryland Zoo in Baltimore, Augustine had worked with crocodiles before using techniques developed for training chickens. (Birds and crocodilians are distantly related, and share an aptitude for language.)

Together with wild animal keepers Megan Baumer and Melissa Mohring, curatorial fellow Melissa Nelson, and curator of herpetology Jennifer Pramuk, Augustine embarked on a mission to train her scaly pupil. Part of their goal was practical—Muru tended to be aggressive around his new keepers, and, as Augustine said, “Nile crocs are known to be unpredictable in the wild.”

But training also serves another purpose: Once the crocodiles bond with their keepers, they become more self-confident, and at ease with their surroundings. Rather than acting out, the animals act more like themselves. Naturally, better health and an increased metabolism also result from the physical workout sessions.

Mohring recalled the way a training regime had helped to energize the zoo’s false gharials, another type of crocodilian. “It caused a behavioral spark,” she said. “After the training session, they would spend more time investigating their pool and looking for food.”

Mohring also observed the male gharial initiating mating behaviors with the female, a sure sign he was feeling more confident.

The keepers introduced Muru to a target made of a broom handle capped with a black Frisbee. His first task was to gently nudge the target with his nose—rather than sinking his teeth into it, as he’d done previously. Through a combination of a whistle command, the sound of his keepers’ voices, and verbal cues, he learned the new behavior within a few months. After the targeting lessons, the keepers moved on to the next task: stationing. Muru made his trainers proud by following their instruction to remain in place for longer and longer periods, even staying still while they moved around his pool to clean it.

Once the trainers could approach Muru regularly, they were able to teach him other important tasks—climbing onto a scale, allowing blood to be drawn from his tail, and even voluntarily walking down a hallway behind-the-scenes, in order to trade exhibits with another crocodile.

Though Muru’s training process may sound familiar to zoo-goers who’ve seen tiger or sea lion enrichment sessions, one huge difference remains between mammal and reptile training: the food reward. Because crocodiles don’t eat daily meals, but tend to have just a couple big ones each week, food plays a smaller role in the crocodile training sessions. Still, the keepers were amazed at how little it took to motivate their hefty charges.

In a recent entry in Augustine’s training journal that chronicles Muru's daily accomplishments, the keeper wrote: “Climbed on land, stationed, let Megan touch him, gave him two mice.” Augustine scored him 10 out of 10 that day. “Two mice!” she said, marveling at the modest size of Muru’s reward for all that good behavior. “Two tiny mice!” 

Updated: 7/01/2009