Video from The Royal Parks shows hedgehog caught up in a discarded party balloon
Litter weighing as much as 157 double decker buses was picked up in London's Royal Parks last year in a clean up operation costing £1.3million.
Park bosses said plastic bags filled with left-over picnic waste, pizza boxes, glass bottles, dog poo bags and PPE were a serious danger to wildlife.
They found a plastic bag wrapped around a stag’s mouth, a hedgehog caught in a party balloon and a cormorant with a plastic beer-pack ring round its neck.
It is illegal to leave litter in the 5,000 acres of London's Royal Parks and anyone caught could be hit with a fine.
"In busy London, the Royal Parks are a haven for wildlife and there are simple things we can all do to protect it and help it thrive," said Sir David Attenborough.
"Litter, and especially plastic, is a growing danger to wildlife worldwide, and we can all help by taking it home or using the bins.
"Please also leave the wildflowers and fungi, the acorns and deadwood where they are; all of them are vital parts of the Parks’ ecology.
"Remember to tread lightly and leave no trace of your visit," Sir David added.
Tom Jarvis, Director of Parks at The Royal Parks, added: "Sadly, we’ve all too often seen the devastating impact that dumping litter, leaving BBQs smouldering or treading into protected areas of the parks can have on the environment and wildlife.
"Taking that moment to decide to clear away a bottle or small piece of plastic rather than leaving it behind could make all the difference to the lives of the parks’ wonderful wildlife."