With 75 living chicks and the final three eggs due to hatch this week, the 2019 kākāpō breeding season is set to be the longest on record.

The number of living kākāpō chicks has risen to 75, with the final three due to hatch this week.

The oldest chicks are already beginning to leave their nests at night although they are still returning to sleep there during the day.

Daryl Eason, from the Department of Conservation's Kākāpō Recovery team, says that the sex ratio of the first 49 chicks to be tested is 22 females and 27 males.

The technique for determining the gender of kākāpō, using either a small blood sample or tiny amounts of membrane left in the eggshell after hatching, was developed by Associate Professor Bruce Robertson at the University of Otago.

This season, a genomics team at Agresearch is carrying out the DNA analyses to determine both gender and paternity of all the chicks. Jeanne Jacobs says the team is currently determining the paternity of the chicks, which will prove whether any of the artificial insemination attempts have been successful. The scientists will also determine the gender of the remaining chicks.

As well as analysing living chicks, sex and paternity is also determined for dead chicks and failed fertile eggs.

The long breeding season

The first chick of the 2019 breeding season hatched on 30 January, and with the final one due to hatch this Friday 19 April, this breeding season will hold the records for both the earliest start and latest end to a breeding season.

Scientist Andrew Digby says the extended breeding season is the result of a large number of females renesting.

The total number of chicks hatched so far in this year's bumper kākāpō breeding season is 83, and if three eggs due to hatch this week are successful it will bring the total number of chicks for this breedign season to 86. The remaining eggs were laid by Stella, who was the last female to mate.

There have been 8 chick deaths. The most recent chick death is Pura-3-A, who died suddenly. Cause of death is still being determined, but appears to be liver failure.

Two of the chicks in Hoki's nest have been moved to other nests after their growth rates slowed down. Hoki herself now weighs less than a kilogram, while her three chicks together weighed four kilograms, and Daryl Eason says she was probably just struggling to feed them. The kākāpō team will be giving her a health check and hope that she will be able to cope with her one remaining foster chick.

Leaving home

The first wild kākāpō chicks on Anchor Island are beginning to explore away from the nest at night, although they return during the day to sleep…

Go to this episode on rnz.co.nz for more details