But since moving them to the outside enclosure things have changed.
Reserve supervisor Rhys Mills, who is an accredited kiwi handler, noticed changes in Ataahua's food consumption and behaviour in the lead up to the egg being laid.
Notable signs were less food being eaten by Ataahua as there was little room for food with the egg taking up all the space, and dirt tracked into the pool as Ataahua would frequent it more often to relieve the weight of the egg. And at Ataahua's health check-up, she felt more solid.
"It's just another part of the kiwi soap opera," Matu said.
"We are now waiting for the male, Puha, to sit and incubate the egg," Rhys said.
For kiwi it can take up to 14 days for the male to sit on the egg to incubate it.
After setting up a trail camera to keep an eye on the situation, staff have seen the male exploring the roost box with the egg in and then covering the entrance with dried fern frond when he left.
"These are all strong indications he has assumed some 'ownership' of the egg," Matu said.
"On Sunday night the male spent an hour and 40 minutes in the nest box which is by far the longest period yet and hopefully a precursor to incubation."
But as of time of writing, Puha is still not incubating the egg, 10 days after it was discovered.
"The incubation is around 75 days, and we will leave them to it for at least 20 days before uplifting the egg at around 65 days."
In the past, eggs from Ngā Manu have been taken to Pukaha National Wildlife Centre to hatch as they have all the equipment and expertise for incubation and hatching.
"We've been in touch with Pukaka and the advice has been to let nature take its course with this first egg of the pair.
"If it doesn't end up being incubated we won't uplift it and send it away to be artificially incubated.
"It's more important the pair adopt the best behaviour for the long term so it's not considered to be vital that we intervene on behalf of an egg that we don't even know is fertile."
Ngā Manu staff are hoping Ataahua and Puha will produce more eggs this breeding season now they are an established pair.