The increase in oilseed rape production and its effects on vertebrate herbivores.
The introduction of oilseed rape on a wide scale has caused significant changes in the ecology of some farmland vertebrates. Break-crops like oilseed rape, by replacing ley grass, have reduced the available summer food for species like the brown hare and this may have reduced their abundance. Woodpigeons appear to have benefited from the increased quality of winter forage, and there is evidence that their survival rates and numbers are increasing. Also changing crop quality has implications for wildlife, and there is evidence that lower glucosinolate levels increase its palatability for herbivores. This can lead deer to eat excessive amounts of a crop which is toxic to ruminants. This has caused extensive mortality amongst continental deer.