While male kakapo "boom" for a mate every year, females breed when there is an abundant food supply, a likely occurrence this year. Photo Gideon Climo. The booming of the male kakapo this breeding season is likely to be followed by an unprecedented population boom, with experts predicting a 50% increase in the population of the critically endangered bird species.
There were only 91 of the flightless parrots in existence but that number was set to increase, with more than 50 chicks predicted this season, national kakapo recovery team leader Emma Neill said.
Rimu trees, a vital food source for the kakapo on Codfish Island, are expected to fruit this summer, and the last time this happened, in 2002, 24 chicks hatched, she said.
In March and April, seven chicks hatched on Codfish Island, but one died of natural complications.
When the chicks hatch next March, the population of kakapo is expected to pass the 100 mark for the first time since the 1970s, she said.
"This is a huge milestone for the kakapo and is significant for its future."
With birds as young as 6 showing they were capable of breeding, the number of females expected to breed this season was 38.
"Females for us are the key. A female chick is extremely precious."
While males "boomed" for a partner every breeding season, females bred when trees masted (fruited) heavily.
A rimu mast can occur every three to five years in a rimu-dominant forest like Codfish Island, and the signs indicated this year would be one of those, Ms Neill said.
"The males are always up for breeding every year, but the females are keyed somehow to the rimu trees."
The Wellington-based nine-strong national kakapo team will relocate to the Southland Conservancy in the coming months, following a recommendation by the Department of Conservation.
Up to four staff work on Codfish Island year-round, with a team of volunteers likely to join them during breeding season, Ms Neill said.