Studying nest success

Last updated 16:00 30/10/2012
Helen Taylor
Kiwi study: Helen Taylor holds a little spotted kiwi that has one of her radio signal transmitters on its leg. She is monitoring the kiwi to measure their hatching success.

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Helen Taylor is monitoring the smallest and second rarest species of kiwi to measure their hatching success.

The little spotted kiwi male is the sole incubator, sitting on his eggs for 60 to 80 days.

For her study, Ms Taylor needs to know how often this substantial effort pays off for the potential fathers and how often the nests are abandoned without a successful hatch.

Ten male little spotted kiwi on Long Island were fitted with special radio tags in June this year. These tags allow her to locate the birds and their nests. They also contain a special piece of software that gives her information on the bird's activity levels, whether or not they are incubating and whether they have hatched an egg. The software has proved incredibly useful to her, as she splits her time between Long Island and her other field site, Zealandia sanctuary in Wellington.

"I make trips to Long Island once every six weeks. But I need to know what the birds are up to for the weeks when I'm not there. The fact that these tags give out activity data means that I've been able to team up with Cougar Line in Picton and have their boat drivers pick up data for me on their way past the island each week. As a result, I have a good idea of who is nesting and who's not before I even set foot on the island, which is incredibly helpful."

The nesting season looks promising with six out of 10 males currently incubating.

By approaching the nests at night, when the males are out foraging for food, and looking inside with a specially designed infrared burrowscope camera, she has been able to confirm that several of kiwi are sitting on two eggs rather than just one.

This is Ms Taylor's second field season on Long Island and experience has taught her not to be too hopeful for all the nests.

"We saw quite a few nest failures last year. Some of the eggs were most likely infertile, but some contained chicks that simply didn't hatch.

"It will be really interesting to see if the patterns of nest failure and success are the same this year and whether it is always the same birds that are successful."

The wider scope of her PhD thesis is inbreeding depression and whether it is having any effect on the species. Little spotted kiwi experienced a population bottleneck of just five individuals 100 years ago. They show very low genetic diversity and could be prone to inbreeding.

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There are currently around 1700 little spotted kiwi in New Zealand, all of which are confined to predator free offshore islands and the Zealandia mainland island sanctuary. Gaining a better understanding of this species and its genetics is important for its future management.

She works closely with the Conservation Department's kiwi recovery team and will be sharing her results with them once her study is completed.

"It's a really exciting project to work on and we're finding out new information about these birds all the time. Hopefully, the study will give us a better insight into inbreeding depression that can be applied to other species too."

- The Marlborough Express

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