The ostrich is the bird that lays the smallest egg for its size. Although it is the largest single cell in nature, an ostrich egg is less than 2 per cent of the weight of the mother. A wren’s egg, by comparison, is 13 per cent of its weight. The largest egg in comparison with the size of the bird is that of the Little Spotted kiwi. Its egg accounts for 26 per cent of its own weight.

An ostrich egg weighs as much as twenty-four hen’s eggs; to soft-boil one takes forty-five minutes. Queen Victoria tucked into one for breakfast and declared it among the best meals she had ever eaten. The largest egg laid by any animal – including the dinosaurs – belonged to the elephant bird of Madagascar, which became extinct in 1700. It was ten times the size of an ostrich egg, nine litres in volume and the equivalent of 180 chicken’s eggs.

The highest mountain is located on Mars. The giant volcano Mount Olympus is the highest mountain in the solar system and in the known universe. At 14 miles and 388 miles across, it is almost three times the height of Mount Everest and so wide that its base would cover Arizona, or the whole of the area of the British Isles. The crater on the top is around 45 miles wide and over nearly 2 miles deep, easily big enough to swallow London.

We traditionally measure mountains by their height. If we measured them by their size, it would be meaningless to isolate one mountain in a range from the rest. That being so, Mount Everest would dwarf Olympus Mons. It is part of the gigantic range which is nearly 1,500 miles long.

Antarctica is the driest place on Earth. Parts of the continent have seen no rain for two million years. A desert is technically defined as a place that receives less than 10 inches of rain a year. The Sahara gets just 1 inch of rain a year.

As well as the driest place on Earth, Antarctica can also claim to be the wettest and the windiest. Seventy per cent of the world’s fresh water is found there in the form of ice, and its wind speeds are the fastest ever recorded. The unique conditions in the Dry Valleys of Antarctica are caused by so-called katabatic winds. These occur when cold, dense air is pulled downhill simply by the force of gravity. Though Antarctica is a desert, these completely dry parts of it are called, somewhat ironically, oases. They are so similar to conditions on Mars that NASA used them to test the Viking mission.

How many nostrils do you have? Four. Two you can see, two you can’t. This discovery came from observing how fish breathe. Fish get their oxygen from water. Most of them have two pairs of nostrils, a forward-facing set for letting water in and a pair of «exhaust pipes» for letting it out again. The question is, if humans evolved from fishes, where did the other pair of nostrils go. The answer is that they migrated back inside the head to become internal. To do this they somehow had to work their way back through the teeth.

Similar gaps between the teeth can also be seen at an early stage of the human birth. When they fail to join up, the result is a cleft palate. So one ancient fish explains two ancient human mysteries. The most recent research on noses, incidentally, shows that we use each of our two external nostrils to detect different smells.

... You don’t see many birds in winter. Most have left your area. Those that stay are not as active. Activity uses energy that is needed to keep warm. The worst problems for birds in winter are getting enough heat and holding on to the heat once it is made. These are problems for all birds. But it is especially true for very small ones. They cannot find enough food. The weather stays so cold for so long that they cannot eat enough to keep alive. But birds have many ways of fighting the cold.

You shiver to keep warm. The heat that you make is made mostly in your muscles. The muscles make more heat when they are active. So one way of keeping warm is to move about, use your muscles. Another way is to shiver. When your body needs heat, the muscles tighten and loosen quickly. They become active. Just as you shiver to keep warm, so do birds.