How San Francisco Zoo's Elly became America's oldest black rhino

San Francisco Zoo was home to Elly, the U.S.'s oldest Eastern black rhino , for 42 years.

Why it matters: Black rhinos remain critically endangered. Their population in the wild decreased by 96% from about 65,000 in 1970 to only 2,300 in 1993, according to the International Rhino Foundation (IRF).

Flashback: Though born in the wild, Elly called San Francisco home from 1974 until she died in 2016. The 1,800-pound rhino was a favorite at the zoo's annual celebrations in observance of World Rhino Day (Sept. 22).

• She enjoyed rolling in the mud, smashing pumpkins and eating watermelon, SFGATE notes .
• Her caretakers loved treating her to "cakes" made of oats and molasses.

Over the decades, she birthed 14 calves and went on to have 15 grand-calves, six great-grand calves and a great-great-grand calf.

• Fun fact: Her grand-calf Boone is named after the San Francisco 49ers' former right tackle, Alex Boone.
• Elly died from age-related conditions at 46.

What they said: "As one of our longest-standing residents, Elly was an outstanding animal ambassador for the endangered black rhino species," San Francisco Zoo president Tanya M. Peterson said at the time of her death.

• "We are grateful to have celebrated many wonderful years with Elly."

The big picture: There are over 6,400 wild black rhinos today, per IRF.