News from South America

Dear PenguinPromises

The weather in the colony has turned really cold, and it has been no fun at all for Promises standing in the freezing cold wind for weeks with half the feathers missing. But now the moult (molt) has finally come to an end and the penguins look really smart in their new shiny black and white plumage.

The end of the moult means that Promises can now set off on the winter migration, which is without doubt one of the best times of year for the penguins. Penguins love being in the water, and they only come ashore when they have to. Because they are birds, penguins are forced to carry out certain parts of their life-cycle on land, such as egg-laying and chick-rearing, but when not forced to come ashore, penguins remain at sea 24/7. No other bird is so well adapted to life at sea, and no other bird can remain at sea for such long periods of time as penguins.

A few days ago Promises left the colony to begin the winter migration. A few penguins still remain here in the colony, but they will also leave during the next few days and the colony will then remain deserted until late September. Having left the colony, the penguins gradually make their way up the coast of Patagonia without ever coming ashore at all. They remain in the sea throughout the day and the night, and even sleep floating in the water.

Penguins lay their eggs and raise their chicks in the extreme south during the summer months, because this far south the days are very long for catching fish, with almost 20 hours of daylight per day during December and January. Now that winter is approaching it gets very cold, with snow, and the days are very short and gloomy. These are not good conditions for raising chicks, so instead the penguins migrate northwards and wait until the weather gets better again before returning to the nest to lay more eggs.

You may wonder why the penguins don’t just remain further north to lay their eggs, instead of travelling all the way back home. The reason is that nearer to the South Pole (and the North Pole too) the days are much longer during the summer than anywhere else on Earth. The equator has hotter weather, but much less difference in daylight between winter and summer, and hence shorter days in summer. The long daylight in summer has two advantages for Promises.

Firstly, as already mentioned, the long hours of daylight allows the penguins to spend up to 20 hours a day catching fish for the chicks. Further from the poles the days are not so long during the summer, so the chicks would receive less food each day if they lived further north.

Secondly, close to the South Pole the virtually constant daylight causes a bloom of microscopic aquatic plants. These microscopic plants only need sunshine to grow and multiply rapidly, and the longer the daylight, the faster they grow. This bloom of microscopic plants in turn causes an explosion of krill and other ocean creatures that feed on the abundant algae. Fish gather in huge quantities to catch the krill and aquatic creatures, and penguins, whales and dolphins move south to take advantage of the large fish and krill populations that gather.
This is called a Food Chain. The extremely long hours of daylight in summer causes a chain reaction that begins with the rapid growth of microscopic plants, and ends with the migration of whales from as far away as Hawaii and Alaska.

Penguins are just some of the animals that migrate long distances to take advantage of this abundance of food during the southern summer. Sand Pipers and other small shore-birds migrate from the northern hemisphere to the southern hemisphere in order to enjoy two summers every year. Whales and dolphins also migrate long distances in order to spend the summer around the South Pole. Compared to whales and Sand Pipers, the penguins’ migration is quiet short.

Ocean currents run up the coast of Patagonia, so that helps Promises travel northwards more quickly. Of course, that same current means that the penguins will have to swim harder when coming back home later in the year. They usually spend the winter off the coast of Brazil, but they have no particular destination in mind.

Because they never come out of the ocean, one part of the coast is much the same as another to the penguins. They only ever see Brazil from a distance. The only penguins that come ashore in Brazil are a handful of penguins that get sick or injured, or which suffer from oil contamination. There are several rehabilitation centres in Brazil that rescue such penguins when they are found on the beaches by concerned sun-bathers. This is virtually the only time that people living in Brazil ever get to see the penguins. The penguins usually remain too far offshore to be seen from the coast.

Penguins are very social animals and they remain together in groups. Penguins like the company of other penguins, but they do not remain with their partner during the winter migration. This is not because of any deliberate desire to separate during the winter. It is just that out at sea it is almost impossible to maintain contact with individual penguins.

On land it is easy to see a long distance, but out in the open ocean a penguin can only see a short distance. The Atlantic Ocean is not like a swimming pool. It has too many tiny particles suspended in the water to see more than 30 or 40 metres at the very most. The distance at which one penguin could identify another penguin underwater amongst all the other penguins is very short indeed.

On the water surface the distance that penguins can see is even shorter, as you can see from the attached photo. Penguins are very low in the water, so they can only see as far away as the next wave. Anything beyond that is hidden behind the waves. When they are momentarily lifted up by a passing wave penguins can get a better glimpse of their surroundings, but most of the time penguins cannot see very far at all in the open ocean.

When penguins catch fish they often have to chase them for quite some distance before they catch them. After such a chase it would be almost impossible to find an individual penguin that was left amongst all the other penguins, so pairs do not even try to remain together. It would be an impossible task.

Penguins keep together in groups during the winter migration, but these groups are made up of random individuals, because it is impossible for penguins to keep track of individual penguins out at sea. Whales and dolphins do remain together as families, but they are much larger and fewer in number, making it easier to identify individuals. Whales and dolphins also use sound to communicate over long distances. Penguins have never developed that ability, perhaps because their bodies are too small to produce such powerful underwater sound waves.

When the penguins return to the colony at the end of their winter migration, the males arrive a few days before the females and wait for their partner at the nest. Magellanic penguins are faithfully to their partner and to their nest. In the same way that we return home to reunite with our family at the end of the day, so too the penguins return to their home to reunite with their partner,
albeit after many weeks. This also enables us to locate and follow Promises year after year. We just call round when they are at home, just like we do with family and friends.

I will write to you again in a few weeks time, by which time the penguins will be somewhere off the coast of Brazil enjoying the sunshine. So whilst we await the return of Promises, I will take the opportunity to share with you the results of our penguin research the next time I write

Best wishes,  Mike

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