Biodiversity is a concept with which some people struggle. President Bush, for one. Well, it is a hard one to grasp. We can look at hard figures: for example, if the present rate of deforestation continues, the next 30 years will see the greatest extinction of living species since the dinosaurs were wiped out 65 million years ago.
It is not easy to relate to so horrific a truth. Biodiversity is an enormous concept. It means the earth's plenty - genes, species, ecosystems. It means the infinite variety of life. Biodiversity means, well, everything. That is a little on the large side for a human brain, so let us turn to kingfishers instead.
Why kingfishers? Because no sane person can fail to revel in the sight of a kingfisher: a flash of blue bursting from the banks of our rivers; because they are so immediately splendid, so obviously worthy of conservation, and because I have a book on my desk that is heaving with kingfishers; blue ones, green ones, red ones, black and white ones and orange ones. Kingfishers the size of wrens; kingfishers the size of pigeons. Paradise kingfishers with tail streamers; stork-billed kingfishers with beaks like clowns' false noses.
There are 87 species of kingfishers in the world. And that, I think, is biodiversity in the most appealing possible form, or forms: 87 different forms. In the lowland rain forest of New Guinea the hook-billed kingfisher feeds at night on stick insects and frogs. By day the shovel-billed kingfisher ploughs up the earth with its grotesque, beautifully fashioned beak; it will turn over a square yard at a time, hunting earthworms.
Many kingfishers have nothing to do with fish at all, or water. Some hawk in the air for insects, others creep about in the undergrowth looking for spiders. Kookaburras are kingfishers, and they will take snakes, often long and dangerous ones. They drop them from a height, and kill them once they are stunned.
But plenty of the Glorious 87 are true fishers, and fishing kingfisher fashion is a complicated business. They fish by diving from a height, and must cope with reflected and refracted light: their retinas can change in an instant from vision through the air to vision underwater. The bird must be able to dive deep enough to reach a fleeing fish, and be smart enough to anticipate the fish's escape route.
Our own kingfisher, sometimes called the river kingfisher, is as neat and as shining a bird as you could wish to see. It is much commoner than non-birding people think, but it is hard to see well. It is, alas, becoming less common as rivers dry up and water supplies are treated in a cavalier fashion.
The most spectacular fisher of the lot is the pied kingfisher, which is found in Africa and Asia. It has liberated itself from the need for a shoreline perch: it will hover above the surface and plunge from a height after its fish. It is the most hilariously whole-hearted bird in the world.
The beautifully drawn plates of kingfishers in the book I am reading, page after page of feathered jewels in improbable colours, variations on one sumptuous theme, is the most vivid sermon on biodiversity you could wish for.
A person who is tired of kingfishers is tired of life: that is what biodiversity means.
