As the birding season wound down in March, and only a smattering of molting adult Adélie penguins remained in the Palmer Station region, Bill Fraser and his team continued their studies of southern giant petrels and skuas. Here, on Humble Island, Fraser measures the culmen – or exposed part of the beak – of a rapidly growing southern giant petrel chick.

Kristen Gorman, left, Peter Horne, and Fraser take measurements of a South Polar skua chick on Shortcut Island.

I weigh a southern giant petrel chick, in bag, on Humble Island.

Brash ice from the calving Marr Ice Piedmont piles up in Hero Inlet, closing in on the birding team’s Zodiacs.

The autumn weather began to worsen in March and snow began to dust the region. Here, a snow squall passes over the Bismarck Strait in front of Palmer Station.

Palmer Station’s main building, which houses the science labs, offices, and the galley.

In February and March, thousands of fur seals begin showing up in the environs of Palmer Station. Here, on Litchfield Island, Kristen Gorman walks warily past fur seals, which are related to sea lions and can move swiftly across the rocky terrain.

Fur seals on Litchfield Island. Fur seals are sub-Antarctic marine mammals and have begun moving into the Palmer Station area in far greater number as the western Antarctic Peninsula rapidly warms.

In the 1820s, the first explorers, seamen, and hunters to reach Antarctica virtually wiped out the population of fur seals in Antarctic and sub-Antarctic waters, including on South Georgia Island. Today, their populations have rebounded sharply and have begun moving south as temperatures warm.

Fur seals cavort in the water off an island near Palmer Station.

A leopard seal.

Icebergs in the Bismarck Strait.

A pair of crabeater seals rests on an iceberg in the Bismarck Strait.

In mid-March a crabeater seal swam out of Hero Inlet and propelled itself to the birding team’s work hut, where the seal rested for a couple of days. Crabeater seals are ice-dependent marine mammals and are common around Palmer Station whenever sea ice is present.

With its benign, dog-log visage, the crabeater seal was a comforting and amusing presence at the station. It paid little attention to passing humans. Peter Horne, Fraser’s team leader, began calling the seal “Winston.”

Hugh Ducklow, left, leads scientific research in the Palmer Station area as head of the Palmer Long Term Ecological Research program, part of a U.S. government program studying climate change. Here, Ducklow, an expert on phytoplankton and director of the Ecological Center at Woods Hole, samples seawater off Palmer Station.

In mid-March, after nearly five months in the Antarctic, I left Palmer Station on the Laurence M. Gould with Bill Fraser and his birding team. In this picture, some of the scientists and staff remaining at the station engaged in a time-honored ritual – jumping into the frigid water as a tribute to outgoing personnel. At right, in front of the black bumper, graduate student Matt Krna can be seen doing a cannonball into the 33-degree water.

Palmer Station as photographed from the outgoing Laurence M. Gould. This autumnal picture is in stark contrast to the ice-covered scene that greeted me when I arrived in late October.

At the start of our voyage back to Chile, the weather was overcast and forbidding, as evidenced by this picture of the Antarctic Peninsula at the head of the Le Maire Strait.

Sunset in the Drake Passage, which separates Antarctica from Cape Horn and the southern tip of South America.

Arriving in Punta Arenas, Chile, a small city, with an end-of-the-earth feel, from which the U.S. Antarctic Program supplies Palmer Station.

Bill Fraser believes it is only a matter of a decade or two before Adélie penguins, whose life history is intimately intertwined with sea ice, disappear entirely from the Palmer Station area. Here, a lone Adélie preens itself in a colony on Torgersen Island that has gone extinct.

Litchfield Island, where Adélies had been breeding for more than 500 years, now has no more Adélie colonies. But the penguins have left behind signs that they were there. Chief among them are these highly polished rocks, which got their sheen from Adélies walking across them for centuries.

On a brilliant late-January day, with the Antarctic peninsular range in the background, an adult Adélie penguin stands in Colony 8, the last colony on Litchfield Island. The death of all the young penguins on Litchfield in the 2005-2006 season signified the end of centuries of Adélie occupation of the island. Bill Fraser says it’s only a matter of time before the striking changes he has witnessed in his three decades at Palmer Station will come to more temperate regions, driving home the reality of global warming to the public at large.