Hani, one of two sister Siberian tigers brought to the Greater Vancouver Zoo in 2012, was found dead this morning by its keepers.

Jody Henderson, general manager of the zoo, said Hani appeared to be healthy but became lethargic, was behaving abnormally and stopped eating yesterday.

"All staff and volunteers at the zoo are devastated by Hani's sudden passing," Henderson said in a statement posted online. "We are hopeful that the full necropsy that will be performed later today will provide some answers."

Hani and her sister, Hana, were born May 22, 2011, at Seoul Zoo in South Korea.

"Hani was the smaller of the two tigers and had a quiet demeanour when compared to her sister," Henderson said.

Hani died just 22 days before reaching her third birthday. This is the second Siberian tiger the zoo has lost in four months.

Sweetie, an 18-year-old Siberian tiger, was euthanized on Dec. 31, after suffering breathing problems, a loss of appetite and ongoing lethargy.

Henderson said the median life expectancy for female Siberian tigers in captivity is 14 years.

The zoo says the wild population of Siberian tigers is estimated to be between 400 and 500 animals, spread across areas of eastern Russia, China and North Korea. 

The Greater Vancouver Zoo is located in Aldergrove, roughly 50 kilometres east of Vancouver.

Hani the Siberian tiger at Greater Vancouver Zoo

Greater Vancouver Zoo says Hani appeared to be healthy but became lethargic, was behaving abnormally and stopped eating the day before she died. (Greater Vancouver Zoo)