KEY POINTS:
A surprise Easter egg has Waikato conservationists excited at the prospect of the first kiwi breeding on Mt Maungatautari in more than 100 years.
The area, 15km southeast of Cambridge, is surrounded by a 48km predator-proof fence and is expected to become New Zealand's main wildlife sanctuary within three years.
This week, Maungatautari Trust chief executive Jim Mylchreest said a transmitter attached to a 5-year-old kiwi male, named Te Tuatahi a Nui, had sent information that indicated he was incubating an egg.
The transmitter sends data on the bird's activity.
"Apparently, the North Island brown kiwi is the only species in which the male takes care of the egg itself. Some other species share the task with the female."
It was thought the female had nothing to do with the incubation because she had done enough in laying the egg.
"It's such a whacking great egg, one-third of the body weight of the kiwi, that it's already put enough stress on the mother in laying something that size," Mr Mylchreest said.
A kiwi egg usually weighed about 500g. The incubation period was about 85 days. Staff at Mt Maungatautari thought the egg was laid about three weeks ago.
"We would love to check the burrow but it is too risky at this stage of the incubation - we don't want to disturb him and frighten him off.
"The next two months will be a tense time for us."
It has been a busy week for Mt Maungatautari staff.
On Thursday, three species of endangered whitebait (kokopu, or native trout) were returned to the area after an absence of about 60 years.
Haven
* Mt Maungatautari is enclosed by a $9 million predator-proof fence, which protects native bush and animals from destruction by pests and predators.
* The 3400ha sanctuary is the biggest in mainland New Zealand.
* Planning for the project started in 1999, and it was completed last year after three years of work.
* The fence has 240km of high-tensile wire, 280,000 screws, 50,000 battens, 8500 three-metre posts, 100,000sq m of mesh, and 850,000 staples.
* Pests such as mice, rats, stoats and cats have been eradicated so tuatara, takahe, kiwi, saddlebacks, and stitchbirds can flourish.
* The sanctuary has about 2500 tui nests.
