The Phoenix Zoo lost its beloved mountain lion, Sierra, who was humanely euthanized this week after dealing with advanced ...

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

Zoo staff made the difficult choice to euthanize one of the zoo’s two female mountain lions, Sierra, earlier in the week. Officials said 17-year-old Sierra was suffering from advanced kidney failure.

The cubs could not have survived in the wild, so in 2008 Sierra and Mystic were sent to live at the Phoenix Zoo. The typical lifespan of mountain lions in the wild is around 10 years, but Sierra ...