An Adélie on Biscoe Point displays typical signs of alarm as I approach too closely to take a photo. The feathers on the back of its head and neck are raised and the penguin turns its head and gives me a wide-eyed look of warning.

January is high summer in Antarctica, and the weather is often sunny and warm around Palmer Station, offering breathtaking views of the peninsular range. Here, on Biscoe Point, a pair of Adélies and their chick bask in the sun.

Icebergs off Dream Island.

Tabular icebergs off Dream Island.

A January sunset.

The team makes its way through brash ice off Biscoe Point. On the right, Adélie penguins walk across the ice as they set out on a foraging trip.

In early January, a pair of recently hatched Adélie chicks sits under a parent. The chicks hatch in late December and early January, and spend an average of 54 days on land before their down is replaced by adult feathers and they head into the Southern Ocean.

Recently hatched Adélie chicks. For the first two weeks of their lives, the chicks stay close to their parents, who provide protection and the warmth of their brood patches.

On a warm day, an Adélie, with a young chick tucked into its brood patch, pants to cool off in the warm January air. Around Palmer Station, many days in January were in the high 30s and low 40s, with temperatures occasionally exceeding 50 degrees F.

As one parent protects the chicks, the other forages at sea, returning to feed its offspring.

An Adélie parent regurgitates krill into the mouth of its chick. The chicks grow rapidly, often gaining several ounces a day before they reach their fledging weight of seven to eight pounds.

Antarctic krill, the crustacean that constitutes the main food of Adélie penguins around Palmer Station. Antarctic krill are a critical link in the Antarctic food chain, feeding everything from penguins, to seals, to whales. But as sea ice disappears along the Antarctic Peninsula, ice-dependent Antarctic krill appear to be in decline.

This picture demonstrates the harsh realities of life in the Antarctic. At center is an Adélie with two healthy chicks. But to the right of the pair is a dead chick that has been abandoned by its parents, probably because one of them has been eaten by a leopard seal. Behind the healthy pair is a hunched-over chick that also had been abandoned and would soon die.

With elephant seals hemming in an Adélie colony on Humble Island, an unusual event takes place inside the colony. At center, an adult Adélie can be seen caring for three chicks. Since Adélies never have more than two chicks, one of the chicks appears to have been adopted by the adult Adélie, a rare event.

Around the middle of January, as the chicks grow to the point where they can keep warm on their own – or “thermo-regulate” – they begin to form large groups of chicks, known as crèches. At the early stage of crèche formation, the chicks still retain their downy feathers.

Crécheing chicks and adults, milling about a colony where recent rains have turned penguin guano into a tacky, foul-smelling mud.

A bustling colony on Humble Island.

By the middle of January, the chicks have developed bulging bellies, and some, like the chick at center, are beginning to lose their down.

As they shed their down and grow blue-black feathers, the chicks begin to take on a moth-eaten appearance.

Créched chicks, looking scruffier by the day.

The chick, at center, sports a remaining tuft on down on its head, giving it the look of an English barrister.

Chicks coated in guano after a rain. The reality of life in an Adélie colony is often a good deal more squalid than the pristine portrayal of emperor penguins in the movie, “The March of the Penguins.”

A large colony on Torgersen Island becomes a guano-filled swamp. The stench in and around such colonies is overpowering.

As the chicks grow rapidly, they become increasingly ravenous and often chase their parents through the colony, begging for food.

As January wears on, the Adélie parents struggle to keep up with the task of feeding their chicks. The parents shuttle constantly to and from the Southern Ocean, where they forage for krill and fish. Here, on Humble Island, parents waddle in an out of the frigid waters.

With the peninsular range in the background, Bill Fraser counts Adélies on Cormorant Island. Fraser has been working in Antarctica since 1974, placing him in a unique position to chronicle the major changes that have swept down the Antarctic Peninsula as temperatures have soared.

On Humble Island, Fraser prepares to grab an Adélie penguin to place a radio transmitter on its back. The transmitters let Fraser and his team know how many hours Adélies are spending on foraging trips, an indication of krill abundance in the surrounding ocean.

An Adélie with a radio transmitter.

A South Polar skua on Shortcut Island.

A pair of brown skuas eating a penguin chick on Torgersen Island.

A South Polar skua incubating eggs on Shortcut Island, where Fraser has been conducting a long-term study of the species.

Fraser prepares to weigh and measure the eggs of a South Polar skua on Shortcut Island. His long-term study has shown that as populations of ice-dependent Antarctic silverfish have sharply declined, South Polar skua populations have dropped, as well.

Many of the South Polar skuas on Shortcut Island have become habituated to Fraser and his team members. Here, Fraser reaches under a South Polar skua to extract an egg for measurement.

A recently hatched South Polar skua chicks sits on plugs of moss, next to a “pipped” egg – one in which the chick inside is in the process of poking its way out of its shell.

The team prepares to measure a pair of young South Polar skua chicks.

Fraser measures the beak of a South Polar skua chick.

On Biscoe Point, Fraser prepares to place a leg band on a brown skua. He has conducted a long-term study of brown skuas, which shows that as Adélie penguin populations have fallen sharply around Palmer Station, so, too, have numbers of the Adélies’ main terrestrial predator, the brown skua.

A southern giant petrel and its chick on Humble Island. Fraser and his wife, Donna Patterson, have conducted one of the longest-running and most comprehensive studies of southern giant petrels, which are threatened in much of the southern hemisphere by long-line fishing.

A pair of southern giant petrels with their chick. Although they have a reputation as fearsome scavengers, Fraser and Donna Patterson have succeeded in habituating a population of southern giant petrels on Humble island, enabling the scientists to weigh and measure the petrel chicks. The metal tag on the rock, at right, contains the nest number.

Fraser measures the beak of a southern giant petrel chick, as its parent looks on. The habituated petrels sometimes crawl into Fraser’s lap.

Elephant seals on Humble Island. The seals occasionally rumble through the Adélie colonies, crushing eggs and killing chicks.

As populations of Adélie penguins plummet along the northwestern Antarctic Peninsula, sub-Antarctic penguins, which prefer warmer climes, are moving in. The main incoming species is gentoo penguins. Here, on Biscoe Point, a pair of gentoo chicks snuggles under their parent. Gentoos, which are slightly larger than Adélies, are readily identifiable by the white patch of feathers over their eyes and their reddish-orange beaks.

Gentoo penguins on Biscoe Point, with Mt. William in the background.

Gentoo penguins on Biscoe Point, with the peninsular range in the background.

Gentoo penguins, with rapidly growing chicks.

Another sub-Antarctic penguin species moving more slowly into the Palmer Station region is the chinstrap penguin, shown here on Dream Island.

Chintrap penguins with chicks on Dream Island.

A gentoo penguin, with its chicks, and a chinstrap penguin.

Adélie penguin, left, outnumbered by chinstrap penguins on Dream Island.

This scene of a tiny colony of Adélie penguins is increasingly common around Palmer Station as Adélie populations plunge.

On Litchfield Island, Bill Fraser stands near the last remaining adult and chicks on the island. Within several days, the colony was wiped out by brown skuas, bringing to an end at least 500 years of Adélie habitation on Litchfield Island.