Humboldt penguin

There are 18 species of penguin, all living in the Southern Hemisphere from the Galapagos Islands at the Equator to the South Pole.

The penguin's ancestor was of the petrel family, which includes albatrosses, fulmars and shearwaters.

Penguins are dark on the back and light on the belly. This camouflages them from enemies and prey. A swimming penguin seen from below is light like the sky. Seen from above, it is dark like the deep water.

Humboldt penguins can be submerged for up to 2 minutes at a time and rely on a dense and insulating plumage when in the cold waters around Antarctica. The penguin is - very conveniently - the bird with the most feathers per square centimetre.

Penguins are very vulnerable on land as they cannot fly, but luckily there are no terrestrial predators where most penguin species breed.

Humboldt penguins live in colonies where they pair up in pairs for life. They typically nest in caves and crevices on rocks.

• Distribution: Coastal Chile and Peru in South America
• Population: Highly endangered - why it is part of the European breeding co-operation
• Weight: Male: 4.9kg and Female: 4.5kg
• Height: 50-70 centimetres
• Mating season: All year round. In Aalborg Zoo, however, only in spring.
• Incubation period: Approximately 40 days
• Number of cubs: 1-2 cubs
• Number of eggs: Usually 2, incubated by both parents
• Food: Schooling fish and 10-armed squid. Prey size: 3.6 - 27 centimetres
• Zoo menu: 7-8 kilos of herring for the group, vitamins, and salt pills
• Lifespan: 25-30 years in the wild. 30-40 years in zoos

Spring is the breeding season

When spring arrives at Aalborg Zoo, the service level in the penguin enclosure is very high, as the birds are laying eggs at this time of year. The zookeepers go around to the nests and feed the penguins that are incubating. The penguins lay their eggs for about 40 days, and they always lay two eggs every few days. The birds lay their eggs in small caves and holes in the rocks of the penguin enclosure. At the bottom there are small round stones and the penguins are given small sticks from which they build a nest. It's important that the nest is built so that it doesn't collect water and moisture, otherwise the eggs risk rotting. In their natural habitat on the coast of Chile and Peru, the eggs are simply laid in a depression in the dry, hard sand and the penguins usually return to the same nest year after year. When the eggs hatch, females and males work together to raise the chicks, and after 12 weeks they are almost the size of an adult penguin.

Fixed relationships and loose connections

In penguins, both males and females breed, and once a pair has found each other, they stay together for life - for the most part, anyway. They say that penguins mate for life, but the zookeepers at Aalborg Zoo have seen some penguins pay a quick visit to the nest of someone they don't mate with. The good thing about penguins not being strictly monogamous is that they can find a new mate if one of the pair dies long before the other. Penguins can get incredibly old, so it's not uncommon for this to happen.

The food is brought to you

At the Zoo, the penguins are fed herring in the appropriate penguin size. Salt and vitamins are added to the fish because the water in the facility is freshwater and because the herring lose some of their vitamin content when they are frozen and thawed. While the babies are young, they eat regurgitated food from their parents, but later they have to learn to eat the whole fish brought in by the keepers. The cubs don't always learn the feeding technique at the zoo from their parents, so keepers take the cubs from their parents just before they leave the nest to teach them. It usually only takes a few days before the penguin chicks are fully aware and comfortable with the fact that it's no longer mum and dad bringing the food, but the one with the grey bucket full of herring. The keepers also prefer to hand-feed the penguins rather than just throwing the fish into the water. Hand-feeding is a great advantage for the keepers as it allows them to check that all the penguins are getting the right amount of food and vitamins, and if one gets sick and needs medicine, the keepers can easily give it to them.

Who is who?

The penguin chicks at the zoo are wing-tagged and microchipped just before they leave the nests, and a feather sample is taken to sex the chicks. The sample is sent for DNA testing at a laboratory in Germany, as there is no visible difference between male and female penguins. And perhaps the penguins themselves can't tell the difference either, because at Aalborg Zoo there are two males that have been mating and nesting for several years, even though neither eggs nor chicks come out of it.

To distinguish the individuals from each other, all penguins wear colourful pearl bracelets on their wings. This allows zookeepers to observe and follow each penguin's behaviour and who is mating, thus keeping track of genetics and doing serious breeding work. Each penguin therefore has its own unique colour combination, and each colour on the tag symbolises a number indicating the penguin's year of birth and number in the flock. Females have the tag on their left wing and males on their right, so keepers can always quickly decode the gender and age of each penguin.

Pillow fight in the penguin facility

Penguins are the bird with the most feathers per square centimetre. The feathers are very small and incredibly dense, so the plumage is insulating and waterproof, keeping the body completely dry and warm. Once a year, the penguins shed all their feathers and new ones grow so that the plumage is always intact. As the penguins shed their feathers, they walk around looking moth-eaten, there are loose feathers everywhere and the facility looks like one big giant pillow fight.

The moult takes about 14 days, during which the parent birds do not go into the water and catch fish because their plumage is not waterproof. In the wild, this means that the parent birds actually fast while moulting. In the zoo, they are still offered food, but they eat far less than the rest of the year. The feather change therefore always takes place in late summer, when the chicks are fish-eating and big enough to fend for themselves, and so that the new plumage is fully grown and completely dense by the time winter comes.

When the chicks hatch, their plumage is grey. The distinctive black and white penguin plumage only appears when they go into moult the year after they hatch. The plumage colours act as the perfect camouflage. If a bird of prey looks down on a penguin swimming at sea, the penguin's dark back hides it in the dark sea. If a predator looks up at the penguin from the water, the light-coloured belly will hide the penguin against the bright sky. There are 18 different species of penguin, all with the black and white plumage.