ST. LOUIS, April 1 (UPI) -- St. Louis Zoo officials say the recent deaths of a polar bear and two simians aren't an indication of something unusual going on.
Steve Bircher, curator of mammals and carnivores, told the St. Louis Post-Dispatch that the deaths appeared to be natural and not the result of problems at the zoo.
"It is not a run of bad luck and it's not systemic," Bircher said. "It's Mother Nature, in most cases."
The newspaper said Wednesday that the latest case was the euthanizing of Hope, the zoo's last polar bear, on Monday. Hope had a liver tumor and was 23 years old -- at the top of the natural life span of polar bears in captivity, Bircher said.
Hope's demise came on the heels of the February death of a chimpanzee that was suffering from an enlarged heart.
A gorilla died two weeks later when it tore apart a rope in its enclosure and accidentally strangled itself.
At the same, a herpes virus struck two elephants but they are expected to survive, the newspapaer said.
Bircher said at the same time, the zoo has been seeing a spike in the number of animal births, the Post-Dispatch reported.