A chimpanzee at the Wellington Zoo has pulled out an ear plug that vets designed in a last-ditch effort to save her hearing.

The plug was to stop 33-year-old Cara putting sticks and straw in her right ear, in which she has a persistent infection.

Photo: RNZ / Alexander Robertson

The zoo's veterinary sciences manager, Lisa Argilla, said they knew there was a possibility Cara could remove the plug but it was their last chance to save the ear.

"This was our last shot to save Cara's ear before resorting to ear canal ablation surgery which means removing the entire ear canal, so it was absolutely worth trying."

Her left ear canal has already been removed, and vets are worried she will now go completely deaf after they operate to remove her right canal next month.

Wellington Zoo primate keeper Jacqui Hooper said the ear plug did not stay in for long.

"That plug wasn't very Cara-proof. She's pretty clever and very, very intent on getting things out of her ear - so she got that out pretty quickly.

"So now we've got the problem where we've just got an ongoing ear infection."

The zoo said this could cause some problems as Cara may not be able to hear verbal communications.

However, it said that, as for humans, a large part of Chimpanzee communication is through facial expressions, body language and gestures, so she would still be able to function within the group.

Photo: RNZ / Alexander Robertson

Photo: RNZ / Alexander Robertson

Photo: RNZ / Alexander Robertson