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There’s a lot more to the departure of Denver Zoo’s polar bears than you’ve heard

Stressed-out grizzlies, antiquated habitats and an uncertain master plan all played a part

Lee, one of Denver Zoo's former polar bears, is photographed on January 24, 2013. He was transferred to the Columbus Zoo in Ohio in November 2018. (Courtesy of Denver Zoo)
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Last year, a federal animal-welfare inspector visiting Denver Zoo observed something worrisome: For long stretches at a time, the zoo’s male grizzly bear paced back and forth in his enclosure.

He paced for 10 straight minutes one morning. When the inspector returned the next afternoon, the bear was pacing again. Over and over and over.

“This appeared to be a repetitive, rigid pattern,” the inspector, from the U.S. Department of Agriculture, wrote in her report.

And it was a bad pattern — a sign that the bear, named Kootenai, was stressed. The zoo’s female grizzly bear, Tundra, also showed signs of stress by swinging her head.

That inspection now provides insight into the chain of circumstances leading to the zoo’s sudden announcement this year that it would relocate its two wildly popular polar bears to new zoos. (The bears have since been moved to new homes in Ohio and Alaska.)

Decades-old exhibits, lagging funding and an uncertain future at the zoo all contributed more to the decision than has been reported.

Brian Aucone, the zoo’s senior vice president of animal science, said the USDA inspections were not a tipping point in the zoo’s thinking. But they do illustrate the zoo’s problems.

In the report, the USDA inspector blamed the grizzly bears’ stress at least partly on their nearly 100-year-old, concrete enclosure. It was cramped and hard — with only one soft spot, which could lead to fights over who got to plop down on it.

“This enclosure limits the bears’ ability to perform species specific behaviors because it lacks adequate functional and structural elements,” she wrote. She gave the zoo two months to come up with a plan to fix it.

The zoo was already aware of the problems with its grizzly bear exhibit, Aucone said. Since the inspection, the zoo has tried to relieve the stress by allowing the grizzly bears to expand into a neighboring enclosure after the death of a bear that was occupying the space.

But the ultimate solution — at least for the next several years — is to move the grizzly bears into the polar bears’ renovated exhibit. And that required moving the polar bears.

“We needed better brown bear habitat,” Aucone said, in a general reference to grizzlies. “We don’t really have options with brown bears. …There’s not really space for brown bears where I can send them somewhere else.”

Polar bears had been a Denver Zoo fixture for more than 80 years and frequently one of the zoo’s biggest attractions. In the 1990s, polar bear cubs Klondike and Snow captivated the city as few other cultural phenomena have — leading to books and TV documentaries.

When the zoo announced in October that it was relocating its current polar bears — a female named Cranbeary and a male named Lee — it emphasized that the move was for breeding purposes. The pair had not produced cubs in Denver, so maybe, after consultation with a continent-wide network of zoos, new mates in new places would do the trick.

“While our polar bears receive excellent care, it’s important that they are paired with mates who may prove to be better breeding partners,” Hollie Colahan, the zoo’s vice president for animal care, said in a statement accompanying the original news release on the move, which also mentioned the new grizzly bear habitat.

Aucone said this is true — the zoo wanted the best for the bears. But their departures had been foreseen as early as 2015, when the zoo released a new master plan that called for, among other things, a major overhaul of the polar bear, seal and sea lion exhibits, as well as a new entrance on the zoo’s east side.

Those exhibits had also come under scrutiny by the federal inspector last year. In reviewing zoo records, she found multiple instances where the levels of bromine — a chemical used for disinfection — in the exhibits’ pools were well above accepted standards. For instance, the inspector noted two dozen instances where bromine levels in the polar bears’ pools exceeded the acceptable range, including times when the levels were more than double the range’s upper limit.

The excessively high bromine levels potentially caused the eye lesions and other chronic eye problems the inspector noted in the medical records for several seals and sea lions, according to her report. Aucone said the bromine problem was the result of a faulty pump, which has been fixed.

Cranbeary, one of Denver Zoo’s former polar bears, is photographed in her exhibit on July 27, 2016. She was moved to a zoo in Alaska in October 2018. (Courtesy of Denver Zoo)

The polar bear, seal and sea lion exhibits, known collectively as Northern Shores, opened in 1987. But the polar bear exhibit is now seriously behind the times. Like the grizzly bears’ habitat, it is made almost entirely of concrete, with few soft surfaces. It has large swimming pools that the bears seldom used.

“When our exhibit was built many years ago, there was this idea that polar bears swim a lot,” Aucone said. “And they do, but to get to places.”

The Association of Zoos and Aquariums’ Polar Bear Care Manual now calls for polar bear exhibits to be “naturalistic” — with lots of soft surfaces such as dirt and grass, as well as trees, logs and boulders. And they should be big.

“Bears benefit from a large habitat areas that allow expression of their natural behavioral repertoire,” the manual states.

Aucone said the zoos to which Cranbeary and Lee were relocated have larger exhibit spaces for polar bears — exactly what Denver Zoo’s master plan calls for to be built.

Aucone said the zoo is willingly undertaking the massive remodel for the good of its animals. There has been no order from the USDA or the AZA that it has to make major changes to its exhibits, he said.

But Aucone also said the zoo is re-evaluating its plan, after the $70 million it had hoped to get from a city bond package turned out to be only $20 million.

That funding shortfall means the new exhibit area might have to be built piecemeal, instead of all at once. That could further delay how long it takes before the zoo can bring back polar bears.

The zoo will decide on initial steps as early as spring.

“It’s a different scale,” Aucone said. “It’s not a different idea.”


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