Pirongia Te Aroaro o Kahu Restoration Society chairwoman Clare St Pierre says kōkako don't generally live near roads.
"When we knew that the kōkako were nesting close to Grey Rd, our ecologist Dave Bryden said we needed to install a sign to ask vehicles to slow down, to help avoid a kōkako casualty'.
"It was crucial to quickly install a sign to help protect the birds."
As it is the first of its kind, the black and yellow sign was based on a pre-existing kererū sign and cost $100, paid for by Waipā District Council.
Clare says it's exciting to have kōkako living close to urban life where the public can see the birds.
"People tell me they've seen kōkako in the carpark and they're really rapt."
The pair on Grey Rd are now nesting for a second time.
"We are doing all we can to make sure they continue to successfully nest."
Kōkako are nesting on the mountain for the first time in decades, with all four monitored pairs in the management area hatching chicks this season.
Last year 14 kōkako with Pirongia lineage were returned to the mountain — another step towards the society's goal to re-establish a self-sustaining population.
So far, 23 males and 21 females have been released.
