Before her shift, she can be found studying the bush for details for her oil paintings.
"I look at foliage and things like that and I take lots of photos of the bush and then I can superimpose it in the paintings. It's just a magic place.
"It's just inspired me."
Formerly a landscape painter, after her stroke she found it easier to do finer work and switched to painting birds.
Her paintings are also made into cards, which have proved popular with visitors at Pukaha's gift shop.
Now 77, spending time at the wildlife centre took her back to her childhood, Mrs Farmer said.
"I was brought up in Stokes Valley and in those days there were only 60 houses there and there was bush right up to the houses ... it's a feeling that I can't explain, it's just so special."
Age was no barrier to volunteering, she said.
"This gives me so much strength and I come home refreshed -- it's what it's all about."
She encouraged anyone considering volunteering at Pukaha not to hesitate.
"They would be delighted. The warm welcome the volunteers get is very special."
General manager Helen Tickner said volunteers were essential to the running of Pukaha, with 8200 hours worked by volunteers during the last financial year.
"We wouldn't be able to do what we are doing without volunteers. A fundamental part of Pukaha is our volunteers.
"We are all pretty much in awe of people who would give so much."
The centre's volunteers are made up of three groups: people who live on site and work 40 hours a week, local people who volunteer on a more casual basis, and those who help maintain the trap lines.
Mrs Farmer was exactly the sort of person Pukaha needed helping visitors, Mrs Tickner said.
"She's a delight, she's passionate. She loves Pukaha and she loves sharing that -- and that's exactly what we want from our volunteers."
