The controversial field trials currently underway in the United Kingdom are intended to investigate the consequences of GMHT crops for biodiversity. The field trials will be very valuable, but will not tell us what will happen to bird populations. They are carried out on too small a scale. Several decades of intensified agriculture in Europe have had a particularly serious effect on birds, whose populations in the United Kingdom have declined by up to 90 percent in the last 25 years, according to Watkinson. The study showed that a key issue in predicting the impacts on bird numbers was the pattern of farmers' uptake of the new GM technology.
Most fields have very low seed densities.
It's the smaller proportion of fields with high seed densities that is particularly important for bird populations. The researchers predict that the severity of the bird declines will depend upon which farmers are most likely to adopt the GMHT crops. If their use is restricted to intensive farms with low seed densities then the effect will be minor. In their Science paper, Watkinson and his colleagues emphasize that their findings don't just apply to the effects of genetic engineering. The same approach could be used to predict the consequences of other changes in farming practice, they say.