Hot weather has driven hungry magpies to attack donkeys in what is becoming a “critical” problem, a sanctuary has said.

Four elderly donkeys at Radcliffe Donkey Sanctuary in Huttoft, Lincolnshire, are being “picked on” by “flesh-eating” magpies that are inflicting wounds the size of £2 coins onto the animals.

Volunteer Ross Clarke said one particular donkey, Jack, was being made “a meal of” by the birds pecking through a dressing on one of the wounds.

He added that the unseasonably hot weather may be causing the magpies to be behaving more erratically as it has produced a berry shortage, which is one of the birds main food sources in winter.

“The magpies might be hungrier than usual because the winter has not settled down and the hot weather means there are not enough berries going around,” said Mr Clarke.

“We've got a few old residents and Jack is too old to run about like some of the others, and every time he lies down in the sun they just seem to land on him.”

“They've pecked through his fur and made him bleed and keep going back for the same patch. We've seen crows and jackdaws taking a bit of fur for their nests, but we've never seen this before,” he added.