A 60-year-old primate at Perth Zoo has been declared the oldest living Sumatran orangutan in the world.

But do not expect Puan to show much enthusiasm.

Staff at Perth Zoo said while the primate was in surprisingly good health, she had become a little grumpy in her old age.

"Puan's a difficult one," primate keeper Martina Hart said.

"She gets a bit impatient, she stamps her foot when she wants something quickly.

"She demands a lot of respect. She deserves a lot of respect, she's not someone who'll show you outwardly that she's particularly interested in you."

It has taken staff at Perth Zoo several years to clarify how old Puan is.

It was believed she was born in the wild in 1956, earning her a Guinness World Record.

Puan gifted to Perth Zoo

Puan celebrated the milestone by eating some special Indonesian fruit, but was otherwise unimpressed. ( ABC News: Eliza Laschon )

Puan was gifted to Perth Zoo in 1968 by the Sultan Johore of Malaysia in exchange for some native Australian animals including kangaroos, a pair of emus and birds.

The matriarch of Perth Zoo's orangutan colony had 11 children of her own and is a grandmother and great-grandmother.

She has well exceeded the usual life expectancy of her species. Typically, Sumatran orangutans do not live past the age of 50.

"She has some arthritis medication every night and on cold mornings we give her some herbal tea to kick start her, but otherwise she's doing really well," Ms Hart said.

"She's a bit slow to climb nowadays and she does spend a bit more time on the ground than some of the others but she's 60 years old, she's allowed to."

'Still going strong'

Puan's present and past keepers Martina Hart and Pieter Leeflang were on hand to mark the milestone. ( ABC News: Eliza Laschon )

Perth Zoo put on a special breakfast for Puan on Thursday to celebrate the milestone.

But she was not impressed with all the attention, and spent a lot of it hidden under a hessian sack.

Puan's original keeper, Pieter Leeflang, was there to celebrate the occasion after he was part of the expedition where she was collected from Malaysia almost 50 years ago.

"I think poachers must have shot her mother. She was hand-reared but was never a pet," Mr Leeflang said.

"She's still going strong. I don't think she breeds anymore but I hope she'll be around for another 10 years or so."