Dear Penguin Cupcake Towers
Our adopted penguins are now back home after their winter vacations in sunnyBrazil. After weeks of hot sunny weather, it is now back to the cold windy weather of Patagonia. The penguins do not remain in pairs during the winter, so the first thing the adults must do after arriving back in the colony is to reunite with their old partner.
The males arrive back at the colony about 10 days before the females, in order to be certain that they are ready and waiting at the nest when the females arrive. Females will begin looking for a new partner if her previous partner is not at home when she returns, because the eggs growing inside her must be fertilised quickly so that she can lay them. So it is important for the males to be punctual.
The storms damaged the burrow during the winter, filling it with loose soil and causing the roof to partially collapse. So once the penguins paired up, they set about repairing the burrow, and collecting new grass to line the nest, so as to make it nice and soft for the eggs and chicks.
The eggs were laid a few days ago, and I attach a photo of your penguin lying over the eggs to protect them and to keep them warm. Magellanic penguins nearly always lay two eggs, and this was no exception. The eggs weigh about 125g each, which is about the same weight as two hen eggs. Eggs as big as that take some laying, and there was a gap of four days between laying the first egg and laying the second. The eggs will now take about six
weeks to hatch.
The eggs won’t hatch at all unless the adults keep them nice and warm. So the adults must remain lying over the eggs all the time, day and night, for the next six weeks, so that the warmth from their bodies can keep the eggs warm. They take it in turns to do this. One adult goes out to sea to catch fish and to rest, whilst the other keeps the eggs warm. Then after two or three days they change over, and they keep changing over every two or three days throughout the six weeks.
Gradually a tiny cell smaller than a grain of salt grows into a little baby penguin inside the egg, using the yolk of the egg as food. When the baby penguins are nearly ready to hatch, they start calling from inside the egg, talking to the parents, and to their brother or sister in the other egg. This helps them to know when it is time to break out of the egg.
The actual hatching can be a long and tiring job for the baby penguins. The egg shell is hard and strong. It has to be so as not to break. And the tiny baby penguins inside have very little strength, and struggle to break the shell. Thankfully they have a little spike on the tip of their beak, called an egg tooth, which they use to chip at the egg from inside, but it can take the chicks up to 2 days to break the shell, and another day to struggle free.
You might think that the adults would try to help, but being penguins they have no hands, only large clumsy beaks and large clumsy feet. The tiny chicks are very fragile, and easily injured, so it is safer for the chicks to do it themselves, in order to avoid being accidentally hurt.
Anyway, that is still six weeks away, and as the saying goes, one must not count one’s chickens before they have hatched. For the next six weeks the adults must keep a careful eye open for large gulls, called skuas, that would try to steal the eggs if given half a chance. As long as the adults remain lying over the eggs, the eggs are safe, but if an adult becomes distracted squabbling with a neighbor, or leaves the eggs exposed for too long whilst changing over with the partner, a passing skua will readily swoop into the burrow and snatch the egg in its beak as quick as a flash.
Thankfully the adult penguins are very well equipped to chase off predators, using their powerful beak which has a large hook at the tip. A bite from a Magellanic penguin inflicts a deep cut, more than enough to persuade a skua to move along. The adult penguins are too strong and aggressive to be at risk from any predators on land, so the eggs and chicks are safe from predators, so long as the adults don’t leave them exposed.
Magellanic penguins are very adaptable, and can lay their eggs in a wide variety of habitats. Here on Magdalena Island in Chile, the soil is sufficiently firm to allow the penguins to dig burrows, which give excellent protection for the eggs and chicks, from predators and from bad weather. However at Cabo Virgenes in Argentina, the soil is too dry and sandy to allow deep burrows. The burrow would simply collapse if the penguins attempted to dig too deep. So instead the penguins nest underneath bushes, which give some protection from predators and bad weather, but not so much protection as a burrow.
Looking after the eggs is a big responsibility – keeping them warm, keeping them safe from predators, and keeping them dry when it rains, for six long weeks. I will write to you again when the eggs have hatched.