The Emperor of Antarctica
Emperor penguins are truly the emperors of Antarctica as not only do they survive through the harsh Antarctic winters but they also are capable of breeding during the worst weather conditions on Earth. The penguins have incredible insulation with several layers of scale-like feathers that pack together so tightly that it takes very strong winds – over 60 knots – for their feathers to get ruffled.
Emperor penguins’ energy conservation skills
With their very small bill and flippers they conserve significant amounts of energy. Their nasal chamber also enables them to recover heat that is normally lost during exhalation. They pack a large amount of energy-giving fat and know how to remain idle during the winter to save precious fuel. A key aspect of their survival is that because they are very social creatures they are comfortable huddling together to keep warm, enabling them to not have to defend territory during adverse weather conditions. In fact, the Emperor penguin is the only specie of penguin that is not territorial. Another energy conservation trick is that the penguins can recycle their own body heat: The Emperor’s arteries and veins lie close together so the blood is pre-cooled on the way to the bird’s feet, wings and bill and is then warmed on the way back to the heart.
Emperor penguins begin their breeding season during autumn when the sea ice reforms and becomes thick enough to support the mass of thousands of penguins. It is interesting to note that the penguins return to the same location each year to breed with the same partner (for first-timers they need to find a mate). It is during this time that the air is filled with penguins singing their songs while performing courtship behaviours that include strutting about in an impressive manner. Once a pair decides to breed, o single egg is laid. Because Emperor penguins lay their eggs on the sea ice there is no nesting materials readily available and so the female hands the egg over to the male for him to look after during the cold winter while she heads off. Over the cold winter the male carefully puts the egg onto his feet and covers it with a skin fold. This enables the egg to be kept nice and warm (around 38°C compared to air temperatures that can plummet to well below -35°C. During this time the males do not eat anything and instead rely on their body fat they have accumulated to survive the winter.
Starving males hungry for a feed
By the time winter is over and the females have come back the males have lost around half of their body mass. Meanwhile, the females have been busy hunting over the winter periods and come back in good shape. Very quickly the males and females identify each other and then they hand over the egg, letting the male go off and feed for the first time in many months. During the rearing of the chicks both parents take turns looking after the chicks, who at this stage become cheeky and call out for any penguin to feed them. By September the chicks have grown down and are very hungry meaning both parents have to take turns to go out and gather food for their young. When it gets cold the chicks learn to huddle to keep warm.
The art of huddling
Because Emperor penguins have to face katabatic winds that blow off the polar plateau as well as intensely cold temperatures, particularly during blizzards when winds can reach up to 200 km/h, the males have learned to close ranks to keep warm. On extremely cold days up to 10 males may pack together. This means they can reduce heat loss by up to 50%, and ensure their fat stores last longer. In fact, temperatures inside the huddle can reach up to a tropical 24°C. Just like a flock of birds with each bird taking over as lead while the others cruise along behind in the, the Emperor penguins take turns in occupying the warmer and colder parts of the huddle. One by one they peel off from the huddle and shuffle, with the egg on feet, off to the next spot, making it a continuous cycle of males passing through the warm centre of the huddle eventually returning to the cold peripheral then back into the warmth. Because of this constant moving the huddle itself moves, with some masses moving up to 200 metres during blizzard conditions.
Emperor Penguins Huddle for Warmth | © Nature on PBS
Bulking up for the cold weather
Emperor penguins forage at depths of 150-250 metres with the deepest ever recorded being 565 metres. On average the penguins will dive for between three to six minutes with one penguin even managing a 22-minute dive. Because the Emperor penguins are near the top of the food chain in the Southern Ocean they have a varied menu to choose from. One of the most popular prey for the penguin is the Antarctic silverfish. Other meals include Antarctic krill and some species of squid. Because the penguins are big on energy efficiency most of the prey items are small and therefore are very cold when ingested, so by keeping the size of the meal small it enables the penguins to bring the food up to body temperature quickly for digestion. Adult Emperor penguins eat between two and three kilograms of food per day on average, but this rapid increases up to 6 kilograms per day when they need to fatten up before a moult or at the start of the breeding season. Eating large amounts of food per day is critical as they need to feed their chicks and the colonies are usually a long way from the fishing grounds.
New Emperor penguin behaviour
In 2014, scientists using satellite imagery and aerial surveys found a new breeding behaviour with four new colonies found on the West Ice Shelf and Shackleton Ice Shelf in East Antarctica and the Larsen C Ice Shelf on the Antarctic Peninsula.
Emperor penguin numbers double
In an earlier study in 2012, scientists from the British Antarctic Survey found that Emperor penguin numbers had doubled. Using extremely high-resolution imagery taken from satellites the scientists found that population numbers were around 595,000 compared to previously believed 270,000-350,000. This is in contrast to a 1992 study that stated a total of 135,000 to 175,000 Emperor penguins lived in Antarctica. The massive increase in population numbers is not due to a huge population explosion but due to better technology enabling scientists to count penguins more accurately. The British Antarctic Survey scientists melded several kinds of high-definition imagery from satellites with more sharper images allowing them to differentiate between penguins, shadows on the ground and even penguin excrement. The scientists also collected population counts on the ground with the ground counts providing the researchers the density of penguin clusters, from which they could multiply the area of penguins calculated by the satellite image analysis into penguin numbers. The researchers also found new colonies and confirmed the location of three previously suspected sites providing a total number of Emperor penguin breeding colonies to 46. The study also estimated that there are around 238,000 breeding pairs.
Emperor penguin trips
Oceanwide Expeditions Weddell Sea cruises sets out to explore the range of the Emperor Penguins near Snow Hill Island. Although they will probably not be able to reach that far through the ice (less than 50 % chance based on previous voyages in the last three seasons), the idea is mainly to situate themselves in or between the Antarctic Sound and James Ross Island, close to the ice-edge and observe the emperor penguins on their way to the open water. Oceanwide Expeditions will use their helicopters to search for individual Emperor Penguins. The Ross Sea Expeditions sail through the Amundsen Sea along and through the outer fringes of the pack-ice. The sailing along and through the ice is very lively, with sightings of single straggling Emperor Penguins, groups of seals on ice-floes, and also Orca's and Minke Whales along the ice-edge, often accompanied by different species of fulmarine petrels.