For animals in the wild, life is defined by the relationship between predator and prey — but incorporating that dynamic into zoos can be extremely difficult.

Asahiyama Zoo tackled the problem this April in its brand new, ¥70-million raptor display. Built to accommodate endangered Blakinston’s fish owls in the future, the house-size black metal cage currently holds three white-tailed eagles. It also features a small pond stocked with rainbow trout intended to supplement the eagles’ regular diet of dead fish supplied by their keepers.

Gen Bando, the zoo director, said that designing the exhibit was tricky.

“There is certainly the ability of the predator to chase its prey, but there is also the ability of the prey to escape its predator. If you put the prey into an environment where it can’t escape, there’s the possibility that it will simply become a cruel one-sided show,” he said. To avoid that situation, the pool in the raptor cage has been designed with nooks and crannies where the fish can escape the eagles.

A different kind of problem arises when it comes to feeding the snakes, said Bando.

“We feed mice to our snakes, and visitors don’t object. But if we fed the snake a rabbit, we’d have a bad scene on our hands. People will only watch if the prey is an animal that’s slightly disgusting to them,” he explained — adding that keepers do feed the snakes rabbits and chickens, but away from the public’s gaze.

In the timber-wolf pen, which shares a fence with the sika deer enclosure, the zoo took a different approach to the predator- prey relationship.

“The animals know the fence is there and that the animal on the other side can’t come any closer, but there is a degree of tension in the relationship,” Bando said.

“We purposely placed the deer’s feeding trough right next to the wolf pen. When the deer press their bodies up against the fence, the wolves come out and bite them. They all get bitten at least once. When that happens, the deer realize, ‘Oh, these guys are scary.’

“We feel it’s important to give them the chance to use their ability as prey animals to jump away when a wolf approaches,” he said.

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