The new silent spring

What is causing the strange disappearance of our songbirds?

Life on the wing: a skylark (alauda arvensis) feeds its young. Photograph: John Hawkins/Corbis

I lost a songbird this spring. I had lived with it for more than ten years, near my home in rural Bedfordshire, 50 miles north of London. I had come to count on its unusual song from early each year, a sound rather like the reverberation of pebbles, issuing from its position high up on telephone wires over a remnant of pasture on the edge of the village. The bird was a humble corn bunting, a species quite easy to overlook, but a delight to hear, when the ear is attuned. I felt privileged still to have it close by. This, after all, is a species that has steadily dwindled and retreated from the agricultural landscape of lowland Britain since the 1960s, disappearing altogether from Wales and Northern Ireland in recent years.

The corn bunting population stays with us year round in Britain. The birds gather in post-breeding flocks in autumn and winter to forage on any spilled grain and wildflower seeds. But it is becoming increasingly difficult for them to find this type of basic food in our agricultural landscape in winter because of changes in farming practice, linked partly – but by no means entirely – to agrochemical use.

I can hear another, more celebrated songbird near my home. As a migrant insectivore, this bird tells a different but closely related story of loss. It is the nightingale and its continued presence and apparent success close to where I live does not reflect the calamity that has befallen it elsewhere. The nightingale, with its fabled, explosively defiant nocturnal warbling, is in retreat. It is following a pattern long established by our farm-dependent wild birds, and now seemingly mirrored by our African migrants adapted to life breeding in woods and parkland.

It is half a century since the American author Rachel Carson warned the world that we risked silencing the spring, bringing birdsong to an end through the excessive use of a new generation of synthetic insecticides. Serialised by the New Yorker in June 1962 and published in full in the autumn of that year, Carson’s Silent Spring is credited with inspiring the modern-day environmental movement. It arrived in Britain a year after its first publication, but its reverberations had already been felt.

What characterised the particular threat that Carson identified and explained in such detail was the alarming number of dead birds and other animals being found in the countryside and even in suburbia. She concentrated on what was happening in North America, but similar processes were under way in the British Isles and beyond. The new insecticides, developed in wartime as potential chemical weapons and now let loose in the environment in what was, in effect, a widespread open-air experiment, differed from pesticides before and since. These products were proving directly lethal to birds, which died “with their feet in the air”. Carson called these chemicals “biocides”: they were inimical to all life. It wasn’t difficult to raise the alarm.

It was straightforward to make the case against the use of these synthetic insecticides, even though industry bigwigs mobilised a campaign to undermine and discredit Carson. Despite their wealth and power, they failed; her courage and stoicism throughout this shameful episode is all the more remarkable when one reflects that she was terminally ill, and had been for a long phase of the four years of research and preparation, unaligned with any major institution, that she devoted to her book.

It took a decade for the US finally to ban DDT, just one of the products that were causing catastrophic declines in iconic species such as the bald eagle in North America and the peregrine falcon worldwide. In the tissues of these predators, the persistent organochlorines were accumulating. Problems of infertility resulted and birds began to disappear. Laboratory studies showed DDT links to cancer in mammals, but it wasn’t until 1984 that the UK government followed the US and banned the substance.

Are we silencing the birds again today? If we take the group of species associated with the farmed environment, the answer is yes, as figures from the RSPB show. As well as the corn bunting, species such as the skylark, lapwing and grey, or English, partridge have declined since the early 1970s, which conservationists take as the baseline (the point when full and formal monitoring of the trend began). These are species of the open field and hedge­row, dependent on our sympathetic farming activity but increasingly silent.

Their difficulties have long been clear to conservation scientists. The declines began in the late 1950s and the 1960s, when Carson carried out her research, but the headlong crash in many bird populations took place from the following decade. Dismantling of old farm infrastructures, subsidy-sponsored drainage of ponds and meadows and ploughing and reseeding of pastures all played a part. There has been a pattern of loss of mixed farming (birds and other biodiversity thrive on variety, as a rule), with often prairie-scale arable fields dominating in the south-east of England and livestock retreating to the north and west. People have disappeared from the rural landscape, too, replaced by machinery that gets ever more enormous. With them has gone the wildlife.

It isn’t just birds. Fears are mounting for the fate of honeybees and bumblebees, and over the impact that their loss is having on the wildflowers and crops that rely on them and other insects such as butterflies for pollination, fruiting and seed production. A new breed of insecticides known as the neonicotinoids has been grabbing headlines recently; research indicates links to the collapse of honeybee colonies.
The products work by being absorbed into the system of plants. Bees ingest the chemicals through nectar and pollen. Several European countries are moving towards bans, but parts of industry are in denial once more, in an obvious parallel with and echo of Silent Spring.

If Carson were alive today, it is likely that the “neonics” would be exercising her scientific and literary mind. The alternatives to these insecticides are likely to come with their own side effects, however, creating wider, often hidden ecological impacts. Crop protection remains a complex matter – yet how do we ensure that a balance is struck, to maintain ecological networks? These macro-scale issues represent the new phase of the conservation challenge in the UK and beyond.

Carson was not opposed to insecticide use per se. Her message was of the need for moderation and care. She called for “humility in place of arrogance” in the ways we apply science to the natural world, and to the farmed environment in particular.

Scientists are increasingly worried about the fate of our woodland birds, some of which may be found in or near suburban settlements. The dwindling numbers of migrant species – such as turtle dove, swift, cuckoo and spotted flycatcher – have prompted researchers to place their African wintering grounds, too, under close scrutiny. The gentle, drowsy purring of the turtle dove will be the next midsummer sound to go, I fear, in line with the trend for this shy, migrant species.

Advances in tracking nanotechnology have made it possible for turtle doves and even smaller birds to be fitted with transmitters, and their progress monitored as they migrate. Scientists can work out where the birds go and where the “hotspots” are. These are places such as coastal wetlands that may be vital staging posts on the migrants’ journeys, and in need of special protection or restoration.

The threats to birds are not confined to the UK, to Europe or even to agricultural land. One in ten of the world’s bird species is threatened with extinction. At this month’s Rio +20 Earth Summit in Brazil (20-22 June), delegates have been asking each other and our governments why we have collectively failed to halt the loss of global biodiversity by the original target date of 2010. Vows have been renewed to get it right by the new target date of 2020. We are approaching the stage where a second failure is no longer an option, if we are to prevent the ecological unravelling of the web of life around us.

Many people have noticed that there are fewer butterflies and bumblebees and that the windscreens and grilles of our cars are no longer as bug-spattered as they once were. Something strange is happening. In the 50 years since Silent Spring was published, we have replaced a specific threat and the grisly spectacle of dead and dying birds with a range of much less visible threats and a creeping, rather than a sudden silence. If you listen carefully, you may hear the quietness mounting.

In recent years vultures have been dying in Asia by the millions, and the cause has been a little surprising. In this instance, it isn’t pesticides. Local people, regular visitors and scientists were initially mystified by the birds’ disappearance. The vulture in the picture above is one of the lucky few, and was taken to a care centre in Hary­ana, India, where it recovered. It had lost the muscular strength even to hold its head up.

Just over a decade ago, research by the US-based Peregrine Fund worked out what has brought three species of vulture to the brink
of extinction. The problem has been traced to diclofenac, an anti-inflammatory drug that has been widely used in Asia to treat livestock for rheumatic pain and other ailments. Its extraordinary secondary effect on the vultures that consume carcases containing the drug is the extreme loss of muscular function caused by visceral gout and kidney failure.

This tragic accident of physiology has killed 99 per cent of three Gyps vulture species in little more than ten years. There has never been a decline like it. Once the most widespread large raptors in the world, these vultures are now absent from huge areas of India. It took longer for even the helpless (and edible) dodo to be wiped out when its island home of Mauritius was colonised by European sailors.

Some people may not accept the argument that nature is worth conserving for its own sake. If the Chromodoris nudibranch (a type of sea slug) becomes extinct, well, so what? My life goes on. So conservationists try the practical or utilitarian arguments. Perhaps, somewhere in its biochemical make-up, that nudibranch held the secret to curing cancer. Or maybe its absence (this is the “butterfly wing-flap” concept – that a butterfly flaps its wings in Japan and three years later, by a domino effect, there’s a tornado in Wantage) will have some kind of catastro­phic, though untraceable, knock-on effect.

The value of vultures is plain, but despite this they have proved a difficult cause with which to elicit public awareness and industry support. It is curious that such a threat of extinction can be happening with only limited media coverage and therefore public awareness. To most people, vultures’ habits aren’t pretty, but what is undeniable, perhaps more so than in the case of any other bird, is their practical economic and social value. Like woodlice, though on a much larger scale, they break down waste material and help transfer it back into the great global mixer, and stop it festering. They can consume quantities of botulism bacteria that at one-billionth the dose would kill an adult human being in minutes. Putrefaction? They eat it up with the proverbial spoon. They stick their bald heads right in there and clean it all out.

Vultures are great at what they do. If you bother them, they may vomit, either to scare you off with the stench of their stomach contents, or to give you an alternative meal. They defecate on their own legs. It works as a disinfectant. Vultures are gross. It’s a dirty job all right, but something’s got do it. And if not the vultures, then who or what?

The lethal effect of diclofenac on vultures has come as a big surprise to industry and to scientists. Conservationists have been taking vultures in for captive breeding, to allow for a viable population in the future to be released where and when it is safe to do so. The Bombay Natural History Society and the RSPB have succeeded in persuading the governments of India, Pakistan, Bangladesh and Nepal to withdraw licences to produce diclofenac. However, it may take many more years to remove the drug altogether from the environment and before vultures can be released again into “safe zones” – vast areas that will require constant monitoring to ensure that no contaminated carcasses are present. Yet there is hope. There is much to be done before the same can be said for the songbirds of Europe.

Conor Mark Jameson’s book “Silent Spring Revisited” has just been publishedby Bloomsbury (£16.99)

 

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