sents an abandoned adelie colony (they use pebbles as nest-building
material). He has been studying seventy-two colonies in a 40-square-
mile area for 25 years now and has watched at least one colony a year
go extinct since 1985. A population of 15,200 breeding pair of adelies
has decreased to 9,200 pairs, while what were only six pairs of chin-
strap penguins has increased to 360 pair.
“So here you have two identical krill predators,” Fraser explains.
“The question we asked ourselves was why the different trends?”
It is a mystery he thinks he has solved.
“On a large scale, we see winter sea ice declining, but on the local
scale we also see warming creating more precipitation as snow,” he
says. “With storms coming out of the north and northeast, we see this
snow accumulating on the southern, leeward side of islands, which is
where the adelie colonies are all going extinct. These birds need dry
ground to lay and hatch their eggs. But the increased snow’s altering
the available nesting and chick-rearing habitat.”
We walk through another dying colony with only a few birds and
chicks where once there were hundreds. Overhead, skuas are gliding
below a cloudy sky, looking for weak or isolated chicks to feed on.
“Once their numbers decline to this point the scavengers have a
field day,” Fraser notes. “Chinstraps breed later in the season after the
snow’s melted and so do better. They’re a weedy species. They adapt
well to disturbed habitat and can also take fish and squid when krill
aren’t available because they can dive deeper and feed at night. They’re
the dandelions of the penguin world.”
In a warmer world, “weedlike” species that are highly adaptable to
disrupted habitat (pigeons, rats, raccoons, deer, elephant seals, and
chinstrap penguins) will displace more specialized “endemic” crea-
tures (tigers, monarch butterflies, river dolphins, sea turtles, and adelie
penguins) that depend on unique ecosystems such as rain forests,
coral reefs, and the Antarctic ice shelf.
In this way climate change is speeding up a global chain reaction
of extinctions that—thanks to other impacts from humans—is already
under way and has been labeled the sixth great “extinction pulse” in
planetary history. The last one, a meteor-based event, took out the
dinosaurs some 60 million years ago.
164 David Helvarg