The trouble with green thoughts is that they are likely to tip you into black pits of despair. "It's like rearranging the furniture on the Titanic," says one conservationist. But amid gloomy warnings of global destruction there are moments of quiet cheer, the occasional flicker of hope in the darkness.
So let us give two cheers to celebrate the successful rearing of two sea eagles in Scotland this month. The white-tailed sea eagle became extinct in Britain in 1916, and they were never going to come back naturally. Sea eagles were wiped out for a simple reason: people shot them. And it needed people to bring them back. The Nature Conservancy Council began a reintroduction programme in 1975, and over a 10-year period 82 birds, taken from the wild in Norway, were released on the island of Rhum, in the Hebrides.
The first sea eagle born in the wild in Britain for 70 years appeared in 1985. There were two the next year, and in 1987 two pairs raised three chicks. This year there were three nests, two of which failed, but the project continues to sustain its momentum. "It maintains our hopes that this magnificent bird will be firmly established in Britain again," says Mike Pienowski, the NCC's senior ornithologist.
Birds of prey are long on magnificence. National emblems, military badges, totems, objects of veneration: birds of prey are something special. They stand for strength and power, but, in truth, they are the most vulnerable of birds.
They are not so much symbols of strength as like canaries in coalmines. The death of the canary showed that something was wrong in the atmosphere of the mine. When the predator population dwindles, it is an early sign that something is going seriously amiss with the environment.
Those who monitor wildlife use birds of prey as "indicator species". They suffer early and noticeably when things go wrong. A sudden change in habitat or pollution level will affect the songbird and small mammal populations, but that is hard to notice. When the sparrowhawk, however, notices that there is not enough to eat and quits the area, absence of sparrowhawk means presence of problem.
For birds of prey, environmental problems are recent things; one of man's "achievements" of the past 200 years. Before that, they were common everywhere. Kites cruised over London all day. Hamlet (admittedly a nominal Dane) had fits of gloom which would have suited him for the job of conservationist, and said he "should have fatted all the region kites with this slave's offal", the slave in question being his uncle.
There is an esoteric argument over whether these kites were the red or the black species, with the consensus favouring the reds. The red kite today is found only in remote places in central Wales.
There is one straightforward reason for the decline of birds of prey since Hamlet's laudable intention of making a special kind of bird table for them. This was the invention of the shotgun. There were blunderbusses in the 18th century and real shotguns by the beginning of the 19th century. These allowed farmers to blast anything that looked unfriendly. More significantly, they started the practice of blasting away at birds for the simple pleasure of it.
This has led to the bizarre phenomenon of managing vast tracts of the country for the benefit of fat, imported birds that are bred to be used as moving targets. The pleasures of shooting pheasants and other game birds gave rise to the practice of killing anything else that might threaten them.
The population of birds of prey has never wholly recovered. The first item of good news for them was, by a wonderfully unsubtle stroke of irony, the two world wars. Conscription summoned the gamekeepers; instantly the bird of prey populations started to recover. The buzzard moved into places in which it had been extinct for years. The number of birds of prey could be directly related to the number of gamekeepers on the ground.
It is fair to say that most gamekeepers have a more enlightened attitude these days. It is now illegal to shoot or poison any bird of prey, or molest young or eggs. But there are enormous pockets of resistance, and it is hard to catch people breaking conservation laws in the privacy of estates.
It is also true that birds of prey take game bird chicks. One way of redressing this is better management of the gamebirds but it is so much easier to blame the birds of prey, and so much easier to find the local sparrowhawk and kill it.
But the biggest crisis since the Second World War was not direct persecution. It was the poisoning of the country with DDT. The point about DDT is that it is residual. For example: assume that an affected insect has one unit of DDT. The vole or songbird eats 10 insects, and so has 10 units. The bird of prey eats 10 voles, and so has 100 units. The result is disaster.
Some birds were killed outright, but the real problem was that birds failed to breed. One reason was that their eggshells became too thin, not robust enough to survive. Here birds of prey, and in particular the peregrine falcon, were the indicator species. Their decline showed us that the country was being poisoned.
Since DDT was outlawed in Britain in 1971, as it now is over much of western Europe and the United States, birds of prey have recovered. Conservationists are almost feeling encouraged. Kestrels, hanging in the air above motorways, now close to their maximum population, hover there as fragile symbols of hope.
Most owls, the elusive peregrine, the golden eagle, the marsh harrier: all these are doing well. The osprey is a great success story for the Royal Society for the Protection of Birds: since 1954 the incidence of this bird has gone from nought to 50 breeding pairs in Britain.
But nobody in conservation ever gets much of a chance to feel smug. It is not always shooting or poisoning that are the enemies: it is the destruction of habitat itself. In particular, it is afforestation: upland moors and lowland heaths disappear, replaced by vast, gloomy, useless-looking forests. The dashing merlin and the stately Montague's harrier are at great risk. Habitat destruction is the constant triumph of greed over good husbandry.
There is never a truly happy tale to tell about conservation. But where Britain's birds of prey are concerned, there is room for a very cautious optimism. Birds of prey are doing all right. But they are still our canaries in the coalmine.
Survival notes:
Kestrel: An increase all over Britain. Their adaptation to suburbs and even cities makes them very noticeable. So does their habit of hunting over motorway verges and railway cuttings - two of the few places where they can find natural grassland with small mammals rooting about in it.
Sparrowhawk: Taken longer to recover from DDT poisoning. Also a difficult bird to spot because of its speed in flight. It is a woodland bird that has adapted to hedgerows; clearly any further loss of either habitat will affect it.
Buzzard: Something of a mystery. It has done very well in recent years in the West Country, and again in the North. There is plenty of suitable habitat in between, but no buzzards. This is possibly because the the land in between Shropshire, Herefordshire, Worcestershire is crammed with good pheasant shoots and the buzzards make easy targets.
Peregrine falcon: Suffered dreadfully from DDT. Its very scarcity and exoticism brought problems: falconers wanted the chicks and egg collectors wanted the eggs. But the peregrine has held on, and more than 1,000 pairs breed annually in Britain. The problems with falconers have not gone away, but the bird populations are at least better able to cope.
Golden eagle: Has not bred in England or Wales for about 300 years, except for a pair which returned to the Lake District and successfully reared young this year. They are largely confined to Scotland, where there are between four and five hundred breeding pairs - close to their maximum. The birds have always been scattered, because they require enormous territories.
Owls: They have done fairly well, with the exception of the barn owl. The bird adapted well to agricultural life at first, but could not keep pace with the new tendency to intensive farming. The modern, sterilized farmyard is no place for a barn owl, either.
Merlin and Montague's harrier: These are the species under the greatest threat.
