Chicago ? The last of three African elephants brought to Lincoln Park Zoo in 2003 — over the objections of animal activists — died shortly following her transfer to a Utah zoo, officials said.

Wankie the elephant’s health deteriorated en route to Hogle Zoo in Salt Lake City, and officials there were forced to euthanized the 36-year-old animal on Sunday. The cause of death was not immediately known, but zoo officials were investigating.

“We wouldn’t expect an elephant this age to die,” Lincoln Park Zoo spokeswoman Kelly McGrath said. “If we did, we might have looked at alternatives to moving her. We moved her because it’s not good to let these animals live alone.”

Wankie was one of three female elephants acquired by Lincoln Park Zoo from San Diego in 2003.

At the time, activists with the People For the Ethical Treatment of Animals argued that Chicago’s harsh winters could be harmful to the elephants. The animals, however, were kept in a heated structure whenever the temperature dropped below 40 degrees, McGrath said.

Officials at Lincoln Park Zoo decided to transfer Wankie after the other two elephants recently died within months of each other.

“We were excited that she would be going to a new home where she would be with other elephants,” Lincoln Park Zoo President Kevin Bell said. “To have such an unexpected tragedy occur is heartbreaking for us all.”

A veterinarian and two elephant keepers accompanied Wankie on the 1,400-mile journey from Chicago to Salt Lake City, McGrath said.

The pachyderm appeared healthy as she was loaded into a truck on Friday, but zoo officials became concerned when she laid down during the trip.

“Elephants can’t lay down for long periods of time,” McGrath explained. “That can cause tissue and muscle damage in their legs. So this was a major concern.”

After they arrived at Hogle Zoo, Wankie was put in a sling and appeared to be fine, McGrath said. Several hours later, however, the elephant began struggling to breathe and a decision was made to euthanize it.

Earlier this year, the oldest African elephant in the United States, Peaches, died at Lincoln Park Zoo at the age of 55. Tatima, a 35-year-old female elephant, died in October from a non-contagious disease similar to tuberculosis, according to zoo officials.