GM crops 'could put bird life in jeopardy'

Wild birds on British farmland could be devastated by the introduction of genetically modified crops, a theoretical study of the effects on the skylark of GM sugar beet suggests.

Wild birds on British farmland could be devastated by the introduction of genetically modified crops, a theoretical study of the effects on the skylark of GM sugar beet suggests.

Scientists used a computer model to predict the impact the beet would have on the amount of food available to a species already threatened by intense agriculture. They found the strong herbicides used with the GM crop could be so efficient at controlling weeds that there would be few wild seeds left for skylarks to feed on.

The scientists, led by Andrew Watkinson from the University of East Anglia in Norwich, say the overall impact of growing herbicide-resistant crops such as GM sugar beet will depend on which farms grow the plants.

If the use of herbicide-resistant crops is restricted to large, intensively managed farms, which have few weeds, the effect will be minor. If they are used more widely by farmers who have until then tolerated more weeds, the impact is likely to be more severe, the report in the journal Science says.

The Government has introduced a moratorium on the commercial introduction of GM crops until field trials designed to assess the impact on wildlife are complete. Dr Watkinson says: "The trials will be valuable, but they will not tell us what will happen to bird populations. They are done on too small a scale.

"One considerable advantage of the methodology we adopted is that it enables us to make predictions now rather than having to wait for the results of a three-year trial."

Farmers growing herbicide-resistant crops will be able to spray weedkillers with a wider effect than those in use today. But that will lead to further intensification, the scientists say. "Although, in some senses, the introduction of GM crops may be no different than the introduction of any other technology that leads to further intensification of agriculture, this new technology might offer a uniquely rapid increase in intensification.".

Already, changes in farming practice have resulted in serious declines in the numbers of wild birds, some of which have fallen by up to 90 per cent since the Second World War. Dr Watkinson says: "It seems likely the widespread introduction of herbicide-tolerant crops will result in further declines for many farmland birds unless other measures are taken."

The computer model indicates a crucial factor in deciding whether herbicide resist- ance affected wild birds was whether farmers left enough weeds in their smaller fields.

Although the model looked only at the interaction of three species - the sugar beet, the skylark and a weed called fat hen on which the birds feed - the scientists believe it could be applied to other crops, weeds and birds.

Scientists not involved in the project say the computer model is welcome, but it may have overrated the effectiveness of the weedkiller commonly used on GM sugar beet. American studies suggest the herbicide is not as effective on weeds as the scientists supposed.

* The multinational biotech company Aventis CropScience is seeking government permission to feed cattle GM maize, grown in British field trials. Aventis says it wants to show GM feed is safe for animals.