And they're off: Scientist's quirky hihi sperm race

It's estimated just a few thousand hihi remain, with most living on Little Barrier Island in the Hauraki Gulf. Photo / File

A Kiwi scientist has just launched what might be one of the weirdest campaigns New Zealand has ever seen: The Great Hihi Sperm Race.

And while that does indeed involve a race between sperm of the threatened native songbird, organiser Dr Helen Taylor says it's all for a rather serious cause.

The Otago University researcher studied what happens to the genetics of populations when they dwindled to small numbers.

Typically, that led to low genetic diversity and increased mating between relatives - now a major concern for conservationists battling to preserve native species close to the brink.

It had already been demonstrated that inbreeding caused infertility in mammals, insects and plants - but no one had yet investigated whether that was true for birds as well, she said.

"If inbreeding does lead to dodgy sperm, it could be bad news for New Zealand's birds, many of which have experienced drastic reductions in population size thanks to introduced mammals and habitat destruction."

As part of her Marsden Fund-supported research, she visited remote islands and predator-free sanctuaries with a specially-designed mobile "sperm lab" to check sperm quality of South Island robins and hihi, or stitchbirds.

"We look at two things to judge the quality of a bird sperm sample: swimming speed and morphology," she explained.

"Swimming speed is just that – how fast do the sperm swim around?

"Morphology refers to the length of the sperm and each of its component parts - the head, the midpiece, and the tail - and also what proportion of the sperm are abnormal.

"It's generally agreed that faster sperm are better, and that longer sperm are faster."

Over the last breeding season, Taylor collected sperm samples from 128 male hihi, and was also able to film the sperm to help calculate how fast they swim.

Dr Helen Taylor with a hihi at Tiritiri Matangi. Photo / Mhairi McCready

As part of that work, she's now kick-started a fundraising effort, in which people could take their own look and pick a bird from one of four sites - Hauturu (Little Barrier Island), Tiritiri Matangi, Bushy Park near Whanganui and Zealandia in Wellington - to back with a $10 bet.

Those who correctly guessed the speediest sperm went in the draw for a prize pack, while all of the proceeds from entries went toward sustaining and building new hihi populations.

It's estimated just a few thousand of the birds remain, with most living in the Hauturu stronghold.