Kiwi hatching season under way
It is no secret kiwi are a strange bird. From the long beak to the inability to fly, they stick out like a sore thumb.
That uniqueness extends all the way to the start of their lives, as the staff at Pu¯ kaha National Wildlife Centre know well.
It is kiwi hatching season at the northern Wairarapa centre, with Mana, a North Island brown, the first kiwi to hatch in early September. There are another four eggs being incubated in the kiwi house.
Wildlife supervisor Jess Flamy has the job of caring for the precious eggs. Although she has spent years caring for hundreds of different kinds of birds, she said she was especially enamoured with kiwi.
‘‘They’re just so different, so unique.’’ Breeding season for kiwi usually starts about July, although they got frisky earlier than usual this year, with the first eggs laid in June.
Eggs are laid in twos, with one usually arriving 20 days after the other, Flamy said.
Kiwi can lay multiple clutches during the breeding season.
The eggs are impressively large in proportion to the bird – Flamy compares it to a human giving birth to an average-sized 4-year-old.
To make things tougher for female kiwi, they are unable to eat as much as usual while producing an egg.
Pu¯ kaha staff and volunteers find eggs thanks to transmitters on the legs of male kiwi, who will sit on the eggs.
The transmitters are programmed to give different readings when kiwi are sitting on an egg, making finding them much easier.
The eggs are left with kiwi for three quarters of their 80-day incubation, then taken and put into warm chambers at Pu¯ kaha.
One of the reasons they are taken is because Pu¯ kaha is unfenced, although it has an extensive trapping programme.
‘‘We go out in the middle of the night, when the male is out of the nest, to get the eggs,’’ Flamy said.
‘‘It’s the same as if a predator was going into the nest.
‘‘It is really sad to have to do, but I hope one day the reserve is safe enough to leave the eggs with the males.’’
The eggs are put into incubation chambers, where the temperature and humidity are controlled to ensure perfect conditions for the developing embryo. But the process is not hands-off. In the wild, all birds will turn their eggs. It ensures the embryo is evenly warmed and develops well.
Flamy said staff at Pu¯ kaha turn the eggs four times a day, but only a little bit each time, as the weight of a kiwi embryo puts it at risk if it falls too far.
As the kiwi grows in the egg, so does an air-filled sac.
Flamy will use a torch to ‘‘candle’’ the egg, which shows the growth of the air sac.
In the right light, candling will also show the veins of the growing kiwi. Once its 80 days are up, the kiwi will pierce the air sac with its beak, taking its first breath, before starting a five-daylong hatching process.
But the newly hatched kiwi, weighing 350 grams on average, does not even get to eat afterwards. It is born with the yolk still attached. That must be absorbed before it can eat.
Newly hatched chicks eating usually brings to mind images of parents flying out to collect food for their offspring.
Kiwi parents are not so maternal. A kiwi chick moves straight to hunting out an adult diet of bugs, slaters and the like, Flamy said.
Although small kiwi have to fend for themselves in the wild from the get-go, Pu¯ kaha kiwi are placed into a pre-release enclosure and fattened up to 1.2 kilograms before going into the reserve. Flamy said the length of the breeding season can vary, depending on the weather.
But things are looking good at Pu¯ kaha this year. It even has a pair of eggs from a breeding pair nobody knew about.