Experts said a “myth seems to have built up” that pumpkins in wooded areas are good for all wildlife – but it can actually make animals unwell and spread disease.
People are being urged to avoid leaving pumpkins in woodlands this Halloween as it can be “dangerous” for wildlife and make animals “very poorly”.
The Woodland Trust and Forestry England warned revellers the fruit can lead to a series of problems for creatures – including hedgehogs, foxes, badgers and birds – and spread disease.
Experts said they have noticed a “worrying trend” in recent years of pumpkins being left in the countryside in a “well-meaning but misguided attempt” to provide food for birds and other wildlife.
But they added it is “really detrimental” and said it can lead to hedgehogs becoming “dangerously dehydrated” because the pumpkins can cause them to have “stomach upsets and diarrhoea”.
Forestry England said around eight million pumpkins could be “part of this year’s fun” – but warned people to ignore tips and online information which tells them the fruit helps wildlife.
Kate Wollen, assistant ecologist at Forestry England, said: “We see many posts on social media encouraging people to leave pumpkins in the woods for wildlife to eat, but please do not do this.
“Pumpkins are not natural to the woodland and while some wildlife may enjoy a tasty snack it can make others, such as hedgehogs, very poorly.
“Feeding pumpkins, or any other food in the forest, to birds, foxes, badgers, deer, and boar can make them unwell and can spread disease.
“Pumpkins are also often decorated and have things such as candles in them. Animals eating the pumpkins could then eat a foreign object and this could kill them.”
Paul Bunton, the engagement and communication officer at the Woodland Trust, said: “A myth seems to have built up that leaving pumpkins in woods helps wildlife.
“People think they’re doing a good thing by not binning them in landfill and instead leaving them for nature.
“But pumpkin flesh can be dangerous for hedgehogs, attracts colonies of rats and also has a really detrimental effect on woodland soils, plants and fungi.”
Instead, people are being urged to turn their pumpkin into soup or even into a birdfeeder – or add to the garden compost.
‘Fleshy fibrous fruit can cause stomach upsets’
Trevor Weeks from East Sussex Wildlife Rescue and Ambulance Service said hedgehogs spend autumn and early winter building up their “fat reserves for hibernation”.
He added: “As a result, hedgehogs can gorge themselves on easily available food like dumped pumpkins.
“Although not toxic to them, the fleshy fibrous fruit can cause stomach upsets and diarrhoea as they are not designed to eat large quantities of fruit.
“This can lead to them becoming bloated and dangerously dehydrated which in turn can be fatal.
“At this time of year, they can’t afford to become ill, or they may not survive the winter hibernation.”
Forestry England said leftover pumpkins can be donated to some zoos, animal shelters, farms and community gardens.