Ross Island penguins struggling

By PHILIP ENGLISH

The penguins on Ross Island in Antarctica are battling to provide food for their chicks for another breeding season.

Two huge icebergs trapping sea ice in McMurdo Sound mean the Adelie penguins have to trek kilometres over the ice before they can enter the sea to catch food.

The icebergs broke off in March 2000, possibly as a result of global warming. Scientists have since recorded thousands of penguins dying. Last year chick numbers fell to 10 per cent of the usual number at Cape Bird and 2 per cent of the usual number at Cape Royds and Cape Crozier.

Kerry Barton, a New Zealand scientist working in the field at Cape Bird, said yesterday that she hoped there would be a 50 per cent success rate among breeding Adelies at Cape Bird. But at the southern-most colony of Adelie penguins at Cape Royds, where there were only about 500 nests out of a usual 3000 to 3500 active nests, things were more serious.

Ms Barton, speaking via a radio link with Scott Base, said it was taking the penguins four days to complete foraging trips for food and this year's breeding season could be as bad as last year.

"They are really bearing the brunt of all the extensive sea ice and the adults are still working really, really hard," she said.

The penguins could experience similar circumstances every 20, 50 or 100 years.

"It is probably quite a significant factor in getting birds to move between colonies, which has genetic implications."

The United States Coastguard ice breaker Polar Sea was yesterday only a short distance from the US McMurdo base, opening up a supply channel to the base. It was hoped the 120m ship would free up the ice off Ross Island to improve the penguins' access to the sea. Ms Barton said it would do little to help until the sea ice broke out to the open sea.

"Around Christmas-time we had a lot of failed breeders and young pre-breeders arrive back in the colony ... but there are still very few chicks so we've got lots of adults and a few chicks."

She said scavenging skua seabirds had taken a lot of eggs and chicks but with more penguins about the skuas were now not having such an easy time.

The Landcare Research scientist from Nelson taking part in a New Zealand and US study of penguin breeding said she would return to New Zealand at the end of this month.

"One of the interesting things for us is how long the birds will try to breed at Cape Royds. Two years of hard ice may make the place a lot less attractive and they may start shifting to other colonies."

Herald feature: Environment