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Penguins “vote with their feet”
It looks like changing ocean conditions
are leading Magellanic penguins from the Punta Tombo reserve in Argentina to
move their colonies north, onto privately-owned land where they are no longer
protected from predators.
“I think of penguins as our ocean
sentinels - they tell us a lot about what’s happening in the ocean and also on
land,” said Dee Boersma of the University of Washington, US.
“Penguins are telling us there are
already problems. The good news is they’re voting with their feet and trying to
colonize new places.”
It seems the penguins are following the
hake, squid and anchovies they prey on, which have shifted north due to
changing ocean conditions. For once, overfishing doesn’t appear to be a factor
- the area is one of the few that hasn’t been overexploited, although this may
change in the future.
According to Boersma the penguins are
typically having to swim 25 miles further from their nest to find food for
their partner left behind incubating the egg. “It’s like if you buy a
house in the suburbs of Chicago and your job gets shifted to Des Moines,”
said Boersma. “The cost of living for the penguin is rising.”
Boersma says that the penguins are
racing their own physiology - one member of a breeding pair sits on the eggs
fasting while the other heads out to find food, swimming back with fish for its
partner in its stomach, which it inevitably starts to digest en route.
The penguins are also starting to breed
three days later on average, because they are finding it harder to find food in
their winter feeding grounds to the north before they return south to breed. If
a female Magellanic penguin does not find enough food to be in good breeding
condition, she will skip a year of reproduction. At Punta Tomba penguin numbers
have declined by more than 20% since 1997, from 300,000 breeding pairs to just
200,000.
What’s more, twelve of the currently
known 19 penguin species are in trouble. “The real elephant in the room is
human numbers and consumption,” said Boersma. “It took 100,000
generations for Earth to reach one billion people, now we can add a billion in
three generations. We have to have control over our consumption if we are to
have penguins.”
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