The Bounty Islands are tiny in terms of area - just some bits of granite jutting out of the ocean. But they are huge in terms of seabirds. James Frankham joins a team researching the erect-crested penguins who breed in this remote archipelago. Recent counts suggest the penguins of the Bounties are doing fine. But this is not the case on the Antipodes Islands, and the researchers desperately want to know why.

The Bounty Islands jut out of the water like giant granite fins. Steep and sheer, with no greenery in sight. They are covered instead by a mottled white - guano or bird poo from the tens of thousands of penguins and albatrosses that come here to breed.

The least studied penguin

The Bounty Islands is one of two remote, subantarctic island groups home to the erect-crested penguin. Stout and handsome, with bright yellow crests that look like elaborate punk rock hairdos, their remote breeding sites means they've not been studied in depth.

But Dr Thomas Mattern of the Tawaki Project plans to change that.

Good news and bad

Using drones to make photo mosaics of all the Bounty islands, Thomas has counted each penguin breeding pair and arrived at a number that suggests the Bounty Island population of penguins has remained relatively stable since the mid-1990s. Good news.

Not the case for their other breeding sites at the Antipodes Islands, where early evidence suggests a significant decline.

But these island groups are a mere 200 kilometres apart - a hop, skip and a jump in penguin swimming distance. How is one group seemingly doing fine while the other is in trouble?

New Zealand Geographic's James Frankham joins an expedition to these remote and wild islands as the scientists begin to unravel this mystery.

Learn more:

• Read the accompanying New Zealand Geographic article by James Frankham, with photography by Richard Robinson.
• As part of this expedition Claire Concannon also visited the Antipodes Islands to learn how they have fared since mice were eradicated.

Go to this episode on rnz.co.nz for more details