The two lions that have lived at Brookfield Zoo since 2008 both had to be euthanized this month leaving the zoo temporarily without lions.

Last week, Isis, a 14-year-old female lion, had to be euthanized one day after a mysterious fall into the moat at the lion exhibit. Isis was euthanized a day later, a little less than two weeks after her 15-year-old male mate, Zenda, was euthanized on Jan. 2 because of declining health due to old age.

Unlike Zenda, Isis’s death was unexpected. She was in generally good health for a lion of her age. On the morning of Jan. 13 Isis fell into the moat at the lion exhibit and suffered some sort of brain swelling that did not respond to treatment. After 24 hours of treatment Isis showed no signs of recovery and the decision was made to euthanize her.

How she fell, and why she didn’t land on her feet is not known. Isis fell about 15 feet from the lion exhibit area into a moat between the exhibit area and the public viewing area. A fall or jump from that distance would not normally cause significant injury to a lion said Bill Zeigler, the senior vice president of animal programs at the zoo.

“Fifteen feet is not a big distance for a large cat,” Zeigler said. “That exhibit has held big cats since 1934 and we have never, ever, had an injury, let alone this type of life-threatening injury. So, what exactly happened, why she wasn’t able to land on her feet, we do not know. No one was there, no one witnessed it.”

While Isis did show some reaction to the death of her long-time partner Zenda, primarily by increased vocalization for a few days, that had subsided and Zeigler said that it is very unlikely that Isis tried to hurt herself or kill herself because of grief over her mate’s death.

“I’ve never encountered anything where an animal would commit suicide,” Zeigler said. “The primal instinct of any animal is survival.”

Isis had been behaving normally before the fall, even after Zenda’s death.

“She was still very responsive, she was still eating well,” Zeigler said. “She was still very active with her staff.”

Zenda had, on the other hand, been in poor health for some time suffering from ruptured discs in his spine and liver and kidney problems. He had difficulty moving about and was in a great deal of pain so the decision was made to euthanize him.

Isis and Zenda came to the zoo in May 2008 and often could be seen grooming each other and sleeping together. They had no cubs. They were among the most popular animals at the Brookfield Zoo with more than 200 people contributing money to support them in the zoo’s Share the Care Program. 

“Isis and her mate were majestic animals who had a strong bond,” Zeigler said. “The staff, who dedicated their lives to care for these charismatic lions, are heartbroken by the loss.”

But their deaths will not be the end of lions at the zoo. While the zoo will be without lions for a few months, two new lions are expected to arrive at the zoo this spring. The zoo had already identified two male lions. Zeigler said the plan had been to bring these two lions to the zoo this summer but the death of Isis and Zenda will probably accelerate that timetable.

“Now, under this circumstance we will probably look at bringing them in some time in the spring,” Ziegler said.

The zoo’s master plan calls for the eventual acquisition and display of a pride of lions, perhaps one or two males and five females to more closely simulate how lions live in the wild.

“The goal for us will be to eventually exhibit a pride of lions,” Zeigler said. 

But it may take five or six years to achieve that goal so the two new lions coming to zoo this year will be temporary but probably stay at the zoo for five to six years.

“Lions will always play a prominent part in our collection,” Zeigler said. “What the new exhibit will look like and where it will actually be compared to where it is now is still a question. . .. Lions are very popular and there is a great conservation story about lions and what’s going on in Africa and their continued loss of numbers in Africa due to habitat loss.”