The drive to squeeze ever more food from the land has sent Europe's farmland wildlife into a precipitous decline

We estimate that, in the past 20 years, ten million breeding individuals of ten species of farmland birds have disappeared from the British countryside. For example, the corn bunting (Emberiza calandra) and tree sparrow have declined for periods of up to a decade at an average rate of more than 5% per year. The declines in bird numbers in part reflect those in the invertebrate and plant populations upon which they depend.

Commentary by John R. Krebs et al. (1999)
Nature 400, 611-612
http://www.pmac.net/silent_spring.pdf