‘Playful right until the end’: Milwaukee Zoo reveals Mimi the rhino passed away

It's a sad day at the Milwaukee County Zoo after a beloved 34-year-old rhino passed away.

The zoo says Mimi had health issues typical of an elderly rhino. She passed away last week.

"Her lead Zookeeper, Ray, describes her as a star pupil for training and how she 'flirted' for scratches and treats. She was playful right until the end," the Milwaukee County Zoo posted to Facebook on Thursday.

There are around 3,700 rhinos in the world right now, according to

, down from an estimated 500,000 rhinos at the beginning of the 20th century.