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BIOLOGISTS in New Zealand are baffled by the sudden death of a large
number of the world’s rarest species of penguin. At least a third of the
400 yellow-eyed penguins that live on the Otago Peninsula, in New Zealand’s
South Island, have died since December – and the final toll may be as high
as 60 per cent. The loss represents around 15 per cent of all yellow-eyed
penguins and threatens to extinguish the mainland population. The disappearance
of this group of penguins is particularly serious for the species because
the birds are genetically distinct from those on the Auckland Islands and
Campbell Island. Their disappearance would narrow the species’ gene pool
considerably.

The first penguins died in December and by February the population had
crashed. Post-mortem examinations showed no sign of poisoning by heavy metals
or pesticides, nor was there any sign of a virus, said John Gill of the
Invermay Research Station in Dunedin. Whatever killed the birds acted very
quickly – in the eight hours they were at sea feeding on the day they died
– and most of the corpses recovered were near their home beaches. ‘Whatever
it is seems to make them sick, then they head for home and collapse on the
beach,’ said Gill.

Suggestions of a cause range from a change in food supply caused by
climatic change, to poisoning by a biological toxin – perhaps from an algal
bloom. The sea has been particularly warm this summer, but temperature alone
would not kill the penguins; nor had the unusual climatic conditions interfered
with the birds’ feeding. None of the dead birds showed any signs of disease.
‘We may be looking at an entity with which we are not familiar,’ said Gill.
‘The problem is that we don’t know much about penguin pathology; we don’t
even know what a normal penguin is.’

With so little to go on, the New Zealand Department of Conservation
has commissioned a study to find out where the birds feed, using radio transmitters.
Once researchers find out what the penguins eat, they may learn what has
been killing them.

In one of the largest salvage operations ever undertaken in New Zealand,
volunteers have been hand-feeding the 120 chicks that were orphaned by the
disaster. Å®ÉúСÊÓƵs believe that it is too early to say if these birds
can restore the population.

A loss of the coastal forests where the birds nest, and the depredations
of cats and stoats, have placed considerable stress on the population even
in normal years.