The Phoenix Zoo lost one of its longtime residents this week. Sierra, a mountain lion, was humanely euthanized due to ...

The Phoenix Zoo had to make a tough announcement this week.Zoo staff made the difficult choice to euthanize one of the zoo’s ...

After 17 long years at the Phoenix Zoo, Sierra the mountain lion was humanely euthanized after experiencing renal failure, the zoo said on Feb. 27. She came to the zoo 17 years ago as an orphaned cub ...