Little spotted kiwi Norton didn’t hatch the eggs
22 May 2012
Norton didn’t hatch the eggs
The 2012 mating season hasn’t gone to plan for Norton the little spotted kiwi. Mrs N produced two eggs before leaving Norton sitting on the nest until hatching – normally 65 to 75 days later. But, after 80 days, the eggs had still not hatched and Norton reluctantly gave up his post. Meanwhile, his neighbours Ira and Kermit smugly produced two healthy chicks, Iraiti and Robin, who have now already left home and are making their own way in the world.
Dr Kristina Ramstad is a postdoctoral fellow at Victoria University’s Allan Wilson Centre for Molecular Ecology and Evolution. She is part of a team of scientists studying why there is such variability in the breeding success of New Zealand’s two rarest species of kiwi.
While none of New Zealand’s five species of kiwi exist in plentiful numbers, populations of the two rarest species – the little spotted kiwi and the rowi – are worrying low. There are 1600 little spotted kiwi, spread over eight isolated locations throughout New Zealand, and 350 to 400 rowi, which all live in South Westland’s Okarito Sanctuary.
The Department of Conservation (DOC) is working hard to increase kiwi numbers through practical interventions and predator control. At the same time, Dr Ramstad is investigating how genetics might play a part in why some individual kiwi produce no chicks each season.
“A full third of adult rowi do not breed and, of those that do, half the eggs left in the wild do not hatch. We need to know why.
“Rowi numbers were down to only 150 or so birds in the mid 1990s and, in a population that small, mating among relatives could be common and lead to inbreeding depression. So it might be genetic differences that explain why some birds always breed and others do not, and why some eggs hatch and others do not.”
Dr Ramstad is using advanced genomics technology to answer these questions. Through New Zealand Genomics Limited (NZGL), the technology to carry out this work is now available in New Zealand. NZGL is a government-funded collaborative infrastructure, which provides genetic sequencing technology and expertise for New Zealand scientists.
“Without NZGL, we would have gone through a much smaller and far less powerful process to try and do something similar. We would have been lucky to find tens or hundreds of genes in total and even luckier to find 10 or 20 genes related to reproduction – may be fewer. Because the Illumina sequencing technology provided by NZGL is so powerful, discovering 5000 to 10,00o genes in less than a year is not unrealistic. The technology is now convenient as well. There’s no longer a need to go overseas, which adds many practical hurdles that together can quickly become insurmountable.
“What we’re hoping to find among these thousands of genes is a suite of genes related to reproduction, hatching and survival – and see if these genes vary between birds in a way that could explain why some are more successful breeders than others.”
Unfortunately, the kiwi genome has not yet been mapped, so the scientists have had to get creative. “To know where to begin looking for these particular functional genes, we’re using the human and the chicken genome sequences as a guide.”
Twelve birds – six rowi and six little spotted kiwi – have been sequenced. Their genetic information will allow the scientists to pin point the genes they are interested in and determine which are responsible for what functions – such as fertility, egg formation, egg shell hardness and disease resistance. Early next year, Dr Ramstad will begin sequencing hundreds of kiwi, using feather samples, and find out how many – if any – of the kiwi’s reproductive woes stem from genetic shortcomings.
“It’s exciting, because we’re going to have a very large resource, that can be used across all kiwi species – not just little spotted kiwi and rowi.”
Dr Ramstad says her genetics work is just one part of a much larger conservation effort and she’s quick to stress how dependent the genetic information is on understanding the behaviour and ecology of individual kiwi.
“Genetics is an important part of a very complex picture, and it only becomes meaningful when it’s connected to the ecological work. If genetic variations among birds match up with the variations observed in their nesting success, then that gives us a practical starting point to work toward increasing kiwi numbers.”
The project involves researchers from Victoria University of Wellington, the Department of Conservation, New Zealand Genomics Ltd and Illumina Australia. Funding is provided by the Allan Wilson Centre for Molecular Ecology and Evolution and the Ministry for Science and Innovation. The project is supported by the Kaitiaki o Kapiti Trust, Ngai Tahu, Port Nicholson Block Settlement Trust, Te Atiawa Manawhenua Ki Te Tau Ihu Trust, Te Runanga o Makaawhio, Waiorua Bay Trust and Zealandia – Karori Sanctuary.