All hail the Emperor penguin
The Emperor penguin is the tallest and heaviest of all penguin species with both males and females reaching over 120 centimetres in height. They are a standout species with their uniform being a black head with a white belly and pale-yellow breast along with bright-yellow ear patches.
The Emperor penguins’ breeding cycle
The breeding cycle of Emperor penguins begins in autumn, around April, when the sea ice reforms and gets thick enough to support the weight of thousands of penguins. Because the penguins return year after year to the same location the first thing they do when they arrive is relocate their mates, and if they haven’t bred before find a mate.
During this time the penguins are wandering around, singing songs and performing courtship behaviours, which range from displays of head bowing and head swinging to walking around in impressive manners. Once a pair has reformed, or for first-timers formed, the female produces a single egg. Because there is no materials for the penguins to build a nest with they have to keep the egg warm until it hatches.
Source: Australian Antarctic Division © Tony Bojkovski
Handing the egg to the male for safeguarding
Over the winter period, the female leaves the colony and hands over the egg to the male who carefully puts it on his feet and covers it with a skin fold. This keeps the egg at a constant 38 degrees Celsius while the outside temperature can fall to below minus 35 degrees Celsius. While the females are away, the males huddle closely together with their eggs to keep warm. During this time they don’t eat anything as they cannot leave the egg and find food. Overall, it takes between 65 to 75 days for an egg to hatch, and by this time the male has fasted for four months. The only thing keeping him alive is his ability to pull on his body fat to survive the winter.
The Emperor penguin heroine
When the eggs have hatched, or about to, the females returns having spent the whole winter hunting. As such, the females are big and healthy with a beautiful coat. Meanwhile the males have lost all their weight and become skinny. The breeding pairs find each other quickly as they recognise each other’s unique call sounds. When they do unite there is a little persuasion required to encourage the male to hand over the egg, or the little chick as he has after all spent the whole winter protecting it.
The chicks are very small weighing only around 150-200 grams, while the adults weight around 22-30 kilograms at this time of year. The chicks have a very thin layer of down and are unable to regulate their own body temperature. It takes on average 50 days for the chicks to develop this ability. Until then they are completely dependent on their parents to keep them warm and so they snuggle up in the penguin’s brood pouch.
During the chick rearing period the colony is highly active with parents coming and going while the chicks wander looking for anyone willing to feed them and so there is a lot of walking and calling going on. Growing requires a lot of energy and so both parents have to go out and gather food. When the chicks are left alone in the colony they form huddles especially during the night to keep warm.
An ice age sanctuary for Emperor penguins
In a recent study, a team of researchers from the universities of Tasmania, Southampton, Oxford as well as the Australian Antarctic Division found that the Ross Sea could have acted as a place of refuge for Emperor penguins during the last ice age. The researchers examined the genetic diversity of modern and ancient Emperor penguin populations in Antarctica to estimate how they have changed over the last 30,000 years and found that only three populations may have survived during this cold period.
The main challenge the Emperor penguins faced during the last ice age was that there was twice as much sea ice compared to current Antarctic conditions and so the distance from the open ocean, where the penguins feed, to the stable sea ice where they breed was probably too far. The three populations that did survive may have done so by breeding near polynyas, which are areas of the ocean kept free to sea ice by wind and currents. One polynya that supported an Emperor penguin population throughout the last ice age was likely to be in the Ross Sea.
The emperor population larger that thought
In a recent study, international researchers have found that there are twice as many Emperor penguins in Antarctica as previously thought. This discovery was made by researchers using high-resolution satellite mapping technology, which provides scientists with an important benchmark for monitoring future Emperor penguin populations. The satellite images allowed researchers to locate emperor penguins using their dark brown guano stains and by zooming in they could identify individual penguins.
One of the key benefits of seeing from space is that researchers don’t have to access challenging conditions to count these species by hand as the temperatures in the areas can plummet to minus 50 degrees Celsius. From the images the researchers counted 595,000 birds which is double the previous estimate of 270,000-350,000 birds.
In addition, because the penguins in their black and white fur stand out from the white snow it meant the scientists could also easily count the numbers of Emperor penguin colonies across Antarctica. In fact, the team found 44 colonies around the coast of Antarctica, with seven previously unknown.
Emperor penguin colony on Snow Hill Island, Antarctica
The Emperor penguin’s hi-tech suit
In another study, scientists from the University of Glasgow have found that Emperor penguins keep warm even when temperatures fall below minus 40 degrees Celsius due to a quirk of their feathers. Previously, it was believed that Emperor penguins retain their body heat because of their thick plumage and layers of fat, however, it has been found that they keep their heat because the surface of their feathers are colder than the surrounding air.
Using thermal imaging on the penguins in Adelie Land, the scientists found that the surface temperature of the birds were four degrees cooler than the surrounding air. The only parts of the penguins warmer than the air were their eyes, beaks and feet, with their eyes only warmer than freezing. Because their plumage is colder than the surrounding air, computer simulators showed their ‘cold coat’ may in fact give back a little heat from the warmer air circulating around them.
While this regained heat is unlikely to reach their skin, it could help reduce some of the heat loss from the body by thermal radiation. In other words, if the penguin’s coat is colder than air it should start to gain heat from its surroundings.