Sharing a dinner treat with the birds could kill – but the odd mince pie is fine, according to the RSPB.

Despite many people thinking all fat is good for birds to give them energy and nutrients, only lard and suet should be used.

Other fats from meat, such as Christmas turkey, are dangerous because they stay soft when cool, ruining the insulation and waterproofing of feathers.

It also provides perfect conditions for food poisoning bacteria such as salmonella to breed and contains a high amount of salt, the RSPB said.

Birds would be at more risk from illnesses and diseases, especially as they are more vulnerable at this time of year because of the cold.

RSPB wildlife adviser Kirsi Peck said: “Please, please don’t use fat from roasting tins to feed garden birds. It’s so great that so many people want to try to give birds extra treats but in this case you could be killing them with kindness.”

Other leftovers that would be better to give instead are mince pie and biscuit crumbs, rice, dry porridge, cooked potatoes or fruit.

Ms Peck said: “Turkey fat could damage birds’ feathers and during winter they need to be in tip top condition to help keep them warm.

“But don’t let this put you off feeding garden birds – there are loads of leftovers that are suitable.”