Back to the ice!
There are many types of terns in the world but the one we saw in Svalbard was, obviously, the Arctic tern. This bird spends its breeding season in the Arctic then migrates as far south as the Antarctic, so it sees two summers every year; it makes the longest migration of any animal on the planet. They are long-lived birds sometimes reaching between 20 to 30 years, breeding at 3 years. They will mate for life and return to the same colony every year. They are very defensive about their nesting sites and will dive-bomb any intruders including humans; other species of birds often take advantage of the tern’s aggressive behaviour by nesting close to the colony ensuring that their own nests are safe from predators. The tern’s nest is built by both parents in a small depression on the ground and one to three eggs are laid. Both the eggs and the chicks are well camouflaged, blending in with the surrounding ground, which helps them to avoid predation.
Besides threats from the air, in the shape of gulls and Skuas, there is a predator on the ground which would find tern eggs and chicks very tasty – the Arctic fox. This fluffy, cuddly looking animal, belies its appearance. It is a fierce little hunter with a varied diet feeding on rodents, eggs, birds, fish, insects and seal pups as well as berries, vegetables and will scavenge polar bear kills if the owner is away. In times of hardship these foxes are able to sniff out a polar bear from a considerable distance and, being very careful, will follow it hoping for a free meal.
The Arctic fox is physically well adapted to the harsh conditions of its environment. It has short legs and muzzle and small ears which means that the body surface area is reduced and protected from the cold. The blood circulation to the pads on the feet is adapted to cope with the icy ground and those pads are furry giving extra protection. The coat is dense and the thick tail is wrapped around the body when the animal is resting acting as a warm duvet. The white colouration is excellent camouflage during the winter but changes to a browny-blue in the summer when it will blend in with the changing colours of the ground. In the spring cubs will be born in underground dens, the litter size averages 5-8 but up to 18 has been recorded; the availability of food will play a great part on how many cubs are born.
The wildlife red list, which runs from ‘of least concern’ through to ‘extinct’, lists the Arctic fox as ‘of least concern’. It does seem that animals that can eat more or less anything, like this little fox, seem to be the most successful which, of course, makes sense.
The Kittiwake is a bird that rarely suffers predation by the Arctic fox, although the fox may sometimes get lucky and catch a bird unawares. As Kittiwakes nest on very steep cliffs the eggs and chicks are relatively safe from ground predators and the chicks, unlike those of other sea birds which are well camouflaged, hatch out to be white. Kittiwakes are pretty little members of the gull family and are common in Svalbard; the one we find in Europe is the black-legged variety, the red-legged kittiwake occurs on the islands off Alaska and the more northerly parts of Russia and is not found in Svalbard. The nesting colonies can sometimes number thousands of birds and the adults feed out at sea on fish and marine invertebrates which they regurgitate for the chicks.
Christmas is nearly here (although some shops think it started three months ago) and an animal that we associate with this time of year is the Reindeer. The one in Svalbard is a sub-species that is only found in this archipelago and while those on the mainland are usually owned by someone, the smaller Svalbard Reindeer are completely wild.
Another difference is that the mainland Reindeer make an annual migration to find food, whereas those in Svalbard stay on the islands; I suppose it would be a long way to swim if they felt the need to migrate.
Reindeer eat a variety of vegetation plus lichen which they often have to access by digging in the snow. Like other deer they shed their antlers and grow a new set every year and the new ones will at first be covered in furry skin, known as velvet, which is shed when the antlers mature. The animals will scratch at the antlers and rub them on the ground and on branches to get rid of the velvet. With other species of deer only the males have antlers but with the Reindeer they are present on both males and the females, although the male’s are much bigger. Males shed their antlers at the end of autumn, after the rutting season, while females keep theirs for much longer, so the Reindeer pulling Santa’s sleigh must all have been female!
After seven and a half months gestation the females give birth, usually to one calf although twins and even triplets occasionally happen.
We’ll be back in Svalbard for one more month, then it’s back to sunny Norfolk. Meanwhile I hope everybody has a good Christmas – with a visit from the Reindeer!