Los Angeles Zoo, Jamie Pham, File, Associated Press
FILE - In this file photo originally released by the Los Angeles Zoo, shows Ruby the elephant on Nov. 14, 2004. Officials say Ruby, a 50-year-old African elephant who was moved to a sanctuary after protests over her confinement at the Los Angeles Zoo died March 29, 2011 at the Performing Animal Welfare Society elephant sanctuary in San Andreas, Calif.

LOS ANGELES — Ruby, an African elephant who was moved to a Northern California sanctuary four years ago amid protests over her confinement at the Los Angeles Zoo, has died. She was 50.

Ruby died Tuesday at the Performing Animal Welfare Society elephant sanctuary in San Andreas, director Pat Derby said Thursday.

A veterinarian, the elephant staff and Derby were all with Ruby when she died.

A necropsy was being performed at the University of California, Davis, Derby said.

Ruby spent 20 years at the Los Angeles Zoo, after being transferred several times and performing with Circus Vargas, Derby said.

Los Angeles Zoo officials said Ruby was one of the oldest African elephants in captivity.

The zoo sent Ruby to the sanctuary, southeast of Sacramento, in mid-2007 after years of lobbying by animal rights activists.

Entertainer Bob Barker donated $300,000 to help pay Ruby's sanctuary expenses.

Before being retired, Ruby had been off-exhibit and living alone because her companion, 48-year-old Gita, died in 2006.

Ruby was sent to the Knoxville Zoo in Tennessee in 2003 to act as an "auntie" in a breeding program, but she never fit in. Taking her away from Gita inflamed animal rights activists because they said it endangered her health.

In 2004, former Mayor James Hahn ordered Ruby returned to Los Angeles.

When Gita died, a zoo investigation found that keepers failed to begin emergency procedures for nearly eight hours after she was found in distress.

Animal activists wanted the zoo to retire Ruby because she was alone, didn't have enough room and because nearly a dozen elephants had died at the zoo since 1968.

When Ruby was sent to the sanctuary, she blended in well with three other elephants, quickly becoming the matriarch, officials said.

A private tree planting memorial will be held for Ruby in the next few weeks, Derby said.

"Obviously, Ruby's life was the ultimate cause of her death," Derby said. "The loss of this magnificent individual is a direct result of captivity and its traumatizing effect on elephants. We must stop the senseless capture and export of wild elephants and keep elephants in the wild."

With Ruby gone, the Los Angeles Zoo was left with one elephant, a 21-year-old Asian bull named Billy. In late 2010, he moved into a staunchly debated, court-contested, $42 million, $3.8-acre "Elephants of Asia" habitat at the zoo.

Tina and Jewel, a pair of Asian elephants who had been together for 25 years, arrived from San Diego to keep him company.

There are about 35,000 Asian elephants left in the wild.