The second of two red panda cubs born at a California zoo dies

The second of two red panda cubs born at the Santa Barbara Zoo in California this summer died over the weekend, the zoo said Monday.

Another cub born to a red panda named Ruby died this month, the zoo said in a statement . The zoo’s staff found that cub dead on July 21.

Red panda cubs die at a rate of around 40%, the zoo said. The pair, born July 2, were Ruby’s first cubs.

The second cub had been “receiving around-the-clock care from our veterinary and animal care teams,” the zoo said in the statement.

“While the cause of death remains under investigation, this loss is heartbreaking for everyone who cared for these cubs and for all who have followed their journey,” it said.

The zoo had taken that cub from Ruby on July 19 after staff members noticed it was not nursing properly, the zoo said.

“He remained in critical condition in a temperature-controlled incubator while receiving tube and bottle feedings, antibiotics and continuous veterinary monitoring,” the zoo said.

The cubs were born to the red pandas Ruby and Raj, and the next breeding opportunity won’t be until next year because it’s seasonal, the zoo said.

Red pandas, which are a little larger than a house cat, are considered endangered, according to the World Wildlife Fund . One reason for their endangered status is the loss of forests and other habitat, the organization says. Over half of their territory in the eastern Himalayas is threatened. They also get killed in traps meant for other animals.

Fewer than 10,000 mature red pandas are estimated to remain in the wild, according to the zoo.