Pumpkins are not natural to the woodland and while some wildlife may enjoy a tasty snack it can make others, such as hedgehogs, very ill. Feeding pumpkins, or any other food in the woodland, to birds, foxes, badgers, deer, can make them unwell and can spread disease as well as attract rats and upset soils, plants and fungi.
Instead, the Woodland Trust advises the public to responsibly dispose of their pumpkin in a food waste bin or compost heap, or even eat it if it's still in a good condition.