It's arrived!

Weighing in at just 173.5g the smallest kiwi chick to hatch at Rotorua's Rainbow Springs Kiwi Encounter emerged from its egg overnight.

Kiwi Encounter has hatched more than 1300 North Island brown kiwi eggs over the years and this latest arrival is the smallest the team has ever nurtured, and is also believed to be the smallest of its species in New Zealand.

"It's very exciting," Kiwi Encounter husbandry manager, Claire Travers said.


"The little chick hatched all on its own overnight and there was a team of very excited staff this morning, one staff member even turned up straight out of bed on her day off, she was so keen for a look."

The 'tiny' egg weighed just 217.6g on its arrival from the Southern Whirinaki Forest and is a single anomaly from this clutch which has produced one other normal sized egg that hatched last week.

By comparison, the sibling egg weighed in at 442.1g, more than double the weight of 'mini', and weighed 369 grams at hatch. Previously the smallest chick to date was McMurdo - his egg was 292g at the same age and he weighed 238.5g at hatch.

All going to plan this chick will be released to establish a founding population of kiwi at the Otanewainuku Kiwi Trust near Tauranga.

The tiny chick now needs a name and naming rights are up for bid on Trademe with all proceeds going to kiwi conservation.

Ms Travers said it was a "complete mystery" why the female had laid an odd smaller egg in a clutch. Possible factors are that it is diet-related, or it could point to issues with her ovaries or reproductive tract.

For just an extra $10 per person, visitors to Rainbow Springs can enjoy a 'behind the scenes' encounter, which includes a peek at the new arrival.

Rainbow Springs involvement in kiwi conservation began in 1995 with the arrival of an orphaned egg and the hatchery has grown over the years to become the largest kiwi hatching facility in New Zealand, successfully incubating and hatching brown kiwi eggs from around the North Island.