Bird flu has been on the rise in Washington state and one sanctuary was hit hard: 20 big cats – more than half of the facility’s population – died over the course of weeks.

The Wild Felid Advocacy Center of Washington is under quarantine amid a devastating bird flu outbreak that has killed 20 big cats.

Twenty big cats, including a half-Bengal tiger and four cougars, died between late November and mid-December at a sanctuary in Washington State after becoming infected with bird flu, according to the facility’s director.