Be sure to turn up the quality so you can get the full experience. It includes highlights from the entire trip.
Cape Roberts: Life on the Coast
While
we focused on the coast during our field season last year, we decided
to come back to spots we weren't able to visit during that season, Cape
Roberts, Marble and Gneiss Points. Cape Roberts was full of all kinds of
wildlife as an active Skua nesting ground with plenty of Weddell seals
nearby on the sea ice.
Left
- A view of the sea ice with Taylor Valley and Explorer's Cove in the
background, sites we covered in the 2012-2013 field season on the way to
Cape Roberts. Right - Wilson Piedmont and Spike Cape, on the way to
Cape Roberts. The Piedmont has been shrinking back over the past several
decades, exposing mummies that had been long buried under ice.
Left
- A Skua pair at Cape Roberts, claiming their territory and challenging
anything that comes near it. Right - A Skua mother and chick, with the
mother doing her thing, calling out to make us aware of her presence.
For those unfamiliar with the term "Skua," I'll
introduce them to you as fat devil birds. The South Polar Skuas
(Skoo-uh) are highly territorial, aggressive, scavenging sea birds that
nest on the Antarctic coast during the summer
and migrate throughout the entire world during the winter. Skuas are
territorial and aggressive for a good reason: these birds are cannibals.
They'll eat each others young when given the opportunity. For example,
in desperate times, a Skua will distract a mother away from her chick,
and the other member of the hunting Skua pair will dive in and grab the
chick while it's trying to hide under a rock. Skuas will also fight to
the death over drinking water ponds, as evidenced by the clearly
scavenged Skua bodies we found nearby.
Left
- A Weddell seal lying out on the sea ice near a big crack in the ice.
The bottom of Mt. Erebus lies in the background just to the right of a
large iceberg. Right - A recently deceased Weddell Seal is being
scavenged by Skuas.
The only other animals nearby are Weddell Seals,
which typically lie out on the sea ice near accessible diving spots.
Unlike other seals in Antarctica, Weddell's
prefer to lay out on the ice all the time, whereas Crabeater seals will
venture out into the open ocean during the summer, with Leopard Seals
following (and hunting) the Crabeaters. Weddell seals will either take
advantage of naturally formed cracks in the ice, or use their teeth to
break through so they can go fishing below. Weddell's were one of the
three main species of seals we were looking for. Judging by Weddell
carcasses we found on the coast, Skuas had a hard time scavenging
carcasses in areas other than the eyes or perhaps they just really like
eyes. So if you fall asleep along the coast, you might want to be
careful about your eyes.
Southern Elephant Seals prefer north facing beaches
and open water. In the project that inspired this one, Elephant Seals
were the main focus since they have a complicated history on the Antarctic
coast, and especially the Ross Sea. Several thousand years ago, when
the Ross Sea had more open water, The largest known Elephant Seal colony
existed in the Ross Sea. Around 1000 years ago, a regional cooling
trend froze the Ross Sea, and the local Elephant Seal population
collapsed, leaving behind only traces of fur that can be found on
ancient beaches under rocks. Though we were searching for other species
of seals in the main focus of the project, we were also looking for
Elephant Seal fur that was left behind to find out more about ancient
Elephant Seal populations as a small side project. Now that the Ross Sea
is warming back up, we want to find out how other seal species will
react to this climate change, and if the Elephant seals might return to
these formerly populated beaches.
Left - Skuas defending territory on the rocks at Cape Roberts. Right - A weather station at Cape Roberts.
And that's about it for this email. I had a few
questions since the last one, mostly about the timing of events and seal
evolution. In terms of the sequence of Geologic events, Antarctica
was not centered on the South Pole like it is today in the Mesozoic. At
the time, Dinosaurs, trees and productive ecosystems existed with
fossils of both in the sediments of the Royal Society Range (near
Marshall Valley). The Ross Sea formed as a rift system, leading to
volcanic activity that is still present with Mt. Erebus. As Antarctica
centered over the South Pole in the Paleogene, the Southern Ocean
formed a circular current which increased the cooling effect around the
continent, which not only drove temperatures down around the continent,
but around the entire world, killing off normal life in Antarctica.
Significant amounts of ice and glacier penetrated into the valleys and
receded repeatedly beginning in the Miocene until the Last Glacial
Maximum in the Pleistocene. The first known seals are known from
temperate environments, including California, in the Oligocene and
Miocene. The three major groups of seals didn't separate until later on
in the Pliocene. The five species of Antarctic
seals are the Southern Elephant Seal (beach loving seals with colonies),
Crabeater Seals (the most abundant seal, and possibly the most abundant
large mammal after humans on Earth), Weddell Seals (sea ice lovers),
and the rare and elusive Ross Seal (rare, elusive, deep divers out in
the open ocean).
That was a quick and dirty summary of the background. If something doesn't make any sense let me know!
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