Updated

Workers and animal lovers at the Smithsonian’s National Zoo are mourning the loss of Muneca, a white-cheeked gibbon who was euthanized on Friday.

The beloved primate was 51 years old, and suffering from declining health, according to Smithsonian officials.

The median life expectancy for the species is about 30 years and Muneca was the oldest in the Association of Zoos and Aquariums’ Species Survival Plan, according to a statement from the museum.

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Zookeepers noticed that Muneca, who was born in Cambodia and came to the Smithsonian from the Maryland Zoo in 1999, was having issues with mobility and appetite loss.

For 19 years, she was an ambassador of her species, teaching visitors and Smithsonian workers about the behavior of white-cheeked gibbons.

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According to the Smithsonian, workers at the zoo recalled Muneca’s “feisty personality” that made her a favorite among the animal care staff.

Muneca would reportedly perch on an elevated platform in her outdoor habitat and watch visitors to the zoo as they strolled past.