Rimu fruit could save k¯ak¯apo¯

A diet of rimu fruit could ka¯ ka¯ po¯ survival, scientists say.

Janet Pitman and Simon Hinkley, of Victoria University, are investigating whether a compound in plants could be added to food for ka¯ ka¯ po¯ to boost their hormone levels, promote egg yolk protein and sperm production and help save the species.

‘‘Their reproduction is really limited because of high numbers of infertile eggs being produced during mast years,’’ Pitman said.

The quirky parrot species only has the opportunity to breed every three to five years during mass fruiting of podocarp forests – when ka¯ ka¯ po¯ eat the forest fruit.

‘‘Breeding only every two to five years really hinders replenishment of the population.’’

And when they do, there are many infertile eggs, hatching failures and a high amount of abnormal sperm production.

Ka¯ka¯po¯ are at risk of extinction with a remaining population of just over 200, and their numbers were also hit by a respiratory disease this year.

A recent grant of $960,000 will aid Pitman’s investigation in to the link between ka¯ ka¯ po¯ breeding and rimu fruit. Pitman said a direct link between the fruiting of rimu trees and successful breeding of ka¯ka¯po¯ has been identified on two of the predator-free islands where the birds lived.

The compounds in the fruit could be raising the birds’ natural hormone of oestrogen levels, bolstering egg yolk protein and sperm production.

Hinkley, a natural product chemist, will be characterising the phytoestrogens in rimu fruit for the research. The idea was to eventually incorporate that compound into supplementary food the birds are provided, Pitman said.

The 2018/19 ka¯ka¯po¯ breeding season was the biggest on record after a super mast year led to unprecedented amounts of rimu fruit.

For the first time in more than 70 years the ka¯ka¯po¯ population hit a record 213 birds. A record 71 chicks survived to juvenile age, far surpassing the previous high of 32. boost