In 1994 kiwi researchers confirmed the worst – about 90% of all wild-born kiwi chicks were dying before they reached six months-of-age. Just 5% were surviving to adulthood. The main culprits – stoats and wild cats.
Something needed to be done, fast, to save kiwi populations already on the brink of extinction – particularly the tiny populations of New Zealand’s most rare kiwi – rowi at Okarito and Haast tokoeka.
The researchers came up with an innovative yet simple solution. They noticed that once kiwi chicks weighed about 1 kilogram, they were better able to find food and defend themselves against the jaws and paws of predators.
So they ran a pilot - taking wild eggs and chicks to keep them somewhere safe during their most vulnerable time. And it worked.
Today the tool is called BNZ Operation Nest Egg™. Every summer breeding season, wild kiwi eggs and young chicks are collected and looked after in captive-rearing facilities and predator-free “crèches”. When the juveniles have reached about 1.2-kilograms and are able to better fend for themselves, they are released back to their wild home.
2008 marks a major milestone for BNZ Operation Nest Egg™ – The 1000th BNZ Operation Nest Egg™chick hatched on 17th February 2008 at Kiwi Encounter in Rotorua! The new chick is named Hūpai, meaning “to overcome”. Hūpai is now at Bushy Park creche near Wanganui. The chick is from a pair of brown kiwi in the Waimarino forest and is due to hatch mid-February. The egg was incubated at Kiwi Encounter at Rainbow Springs, Rotorua. You can follow this special chick’s progress in Kiwi Life and also check out our collection of photos.
A Conservation Success Story
The name for BNZ Operation Nest Egg™ was chosen carefully – taking kiwi eggs and chicks from nests is securing a 'nest egg' of kiwi for the future.
The tool is helping key kiwi populations survive by buying researchers time while they look for solutions to control stoats, wild cats and other predators over large areas of forest.
Without conservation management, only about 10% of kiwi chicks on mainland New Zealand survive their first six months, and just 5% reach adulthood, well short of the 20% survival needed for a population to increase. A BNZ Operation Nest Egg™ chick has about a 65% chance of survival to adulthood once released back into the wild.
BNZ Operation Nest Egg™ is particularly effective for rapidly recovering the populations of the rarest kiwi – rowi numbers at Okarito increased by 25% over six years.
It is also a good tool for re-establishing populations in areas where kiwi have died out (such as at Boundary Stream), for rapidly increasing populations that have declined to just a few individuals (such as at Bream Head), and for restoring larger populations (such as at Tongariro).
Team Effort
Six captive-rearing facilities use the BNZ Operation Nest Egg™ tool: Auckland Zoo, Kiwi Encounter at Rainbow Springs in Rotorua, the Whangarei Native Bird Rescue Centre, Napier's Westshore Wildlife Reserve, and Otorohanga Kiwi House, and Willowbank Wildlife reserve in Christchurch - in partnership with the Department of Conservation.
Since BNZ Operation Nest Egg™ was formally adopted as a tool in 1995, their expertise and commitment have helped achieve a number of landmarks. In early 2007, Auckland Zoo celebrated the hatching of its 150th BNZ Operation Nest Egg™ chick, and later that year, Kiwi Encounter hatched its 500th.
And of course, there’s the 1000th chick due to hatch early 2008.
BNZ Operation Nest Egg™ could not succeed without the knowledge, time and commitment of all the institutions and individuals involved in hatching eggs and raising chicks. Or the ongoing generous financial support of New Zealanders.
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Learning as We Go
Over the years, BNZ Operation Nest Egg™ has helped researchers learn a lot about kiwi behaviour and how they breed, and this has been used to improve the tool and increase the number of eggs and chicks that survive captivity. For example, the discovery that kiwi males turn the eggs during incubation improved the hatching success of salvaged wild eggs, as well as of kiwi eggs laid in captivity. Two other techniques that have been developed to test the health of eggs are:
BNZ Operation Nest Egg™ has also allowed researchers to learn more about the diseases and parasites that affect kiwi, helping them screen for health issues. And work continues on improving techniques to raise chicks.
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Preserving Gene Pools and Adaptations
To ensure the unique gene pools and adaptations of each population are preserved, chicks are always returned to the wild populations from whence they came. They are never mixed up.
Because Maori have always recognised the important relationship between living things and the land on which they were born, there is often a ceremony to welcome the young kiwi back to the place of their birth.
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A Great Success
Since it began in 1994, nearly 1000 birds have been hatched and released back to the wild. The 2002/03 breeding season was very special - the first third-generation egg was laid. The chick’s grandfather was one of the original BNZ Operation Nest Egg™ chicks hatched at Auckland Zoo.
In Tongariro Kiwi Sanctuary, managed by the Department of Conservation, BNZ Operation Nest Egg™ has been so successful in increasing kiwi populations that funding has moved from saving a relatively small number of eggs and/or chicks each year, to widespread predator control throughout the forest. This helps all kiwi in the sanctuary’s population.
BNZ Operation Nest Egg™ will continue to be used where threatened kiwi populations need a boost, or new populations need to be established.
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Egg Candling
How do you tell how old a kiwi egg is?
And how do you know whether it is alive or dead?
Two women who know the best way to answer both questions are Claire Travers, of Rotorua’s Kiwi Encounter, and Suzanne Bassett, of Otago University – between them they have years of experience “candling” kiwi eggs.
“Candling” means shining a bright light into a kiwi egg to light up its contents. What you see tells you whether the egg is alive and, if so, how old it is.
Claire and Suzanne are the force behind the two-day candling workshops held since October 2003, and sponsored by the BNZ Save the Kiwi Trust.
The workshops were sparked by the growing importance of the BNZ Operation Nest Egg™ tool. As the number of wild kiwi eggs collected is increasing, it is important that people have the skills to make sure live eggs are correctly identified and aged.
The two-day practical workshops also teach people the best ways to handle eggs and transport them to the captive rearing centres for artificial incubation.
The first course, in October 2003, was hosted by Rainbow Springs and funded by the BNZ Save the Kiwi Trust. Several have been held since to deal with the overwhelming demand.
The kiwi egg candling courses are open to anyone working with kiwi, either in the field or in a captive environment. Suzanne says a wide range of people have come along – from Department of Conservation field rangers and volunteers, to zoo keepers, community kiwi conservation groups, and possum trappers.
Because it is a hands-on practical course, the core workshop is limited to 25 participants.
A follow-up one-day advanced course is now also available to refresh and extend participants’ knowledge, and present new developments in kiwi best practice.
The courses have lead to a big improvement in hatching success in the captive rearing facilities.
To complement the course’s study guide, BNZ Save the Kiwi Trust has funded a full-colour field guide outlining the different stages of kiwi embryo development.
Dates for upcoming candling courses are notified here. Or you can contact kiwihouse@rainbownz.co.nz for more information. A registration fee is charged, with the BNZ Save the Kiwi Trust funding the rest of the course costs.
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