Calgary Zoo officials say a Siberian tiger cub born early this week has died.
Tigress Katja, who lost a pair of cubs in September, gave birth to the female baby Monday and initially things looked good.
But senior animal care staff had to provide emergency care when the mother left the den and the tiny cub became dehydrated and lost body heat.
Animal care director Dr. Jake Veasey says the newborn died Thursday night.
"Although there were small signs that gave us all some cautious hope, the cub had been entirely dependent on human intervention since Tuesday evening and simply was not strong enough to pull through (despite) receiving the very best of care," he said in a release.
A post-mortem examination overnight confirmed the cub's organs failed. There was no evidence of any trauma, which suggests Katja had provided exceptional care for the first 36 hours of the cub's life.
"The harsh realities of nature are sometimes difficult for humans to accept," said Veasey. "But it appears now that the cub's mother Katja may well have detected health issues which ultimately led to the death of the cub and that in abandoning the cub, she was doing what she has evolved to do and as she would have done in the wild sensing that her cub could not survive."
Siberian tigers are considered endangered and their population continues to decline. Census estimates say there are fewer than 400 adults left in the wild.
Last September, zoo officials were taken unawares when Katja gave birth to twins. Keepers had not known she was pregnant. A female Siberian tiger weighs about 135 kilograms whereas a cub is about one kilogram at birth.
Staff believe the two females died of complications from severe head trauma, which the zoo's head of veterinary services attributed to the actions of an "inexperienced mother."
This time the pregnancy did not come as a surprise. Animal care staff anticipated the birth after observing Katja mating with Baikal from New York's Bronx Zoo.
"The conservation efforts to save endangered species depend upon a multi-pronged approach including captive breeding ... conservation efforts in the wild, research and the effective management of human conflict," said Mr. Veasey.
"This tiny cub losing her battle for life highlights the fragility of the entire Amur tiger population."