The Prince of Wales has ordered a cull of the destructive grey squirrel on his estate in a bid to protect the indigenous red variety, his spokesman has confirmed.
"Humane and lawful" measures to control the population of greys, which carry a poxvirus which is deadly to red squirrels, have been introduced on the Duchy of Cornwall estate.
The grey species, which were first brought over from America in 1876, are also "extremely destructive" in woodlands, stripping the bark from trees and causing a "major impact" on woodland conservation, biodiversity and sustainability, according to the Forestry Commission.
Prince Charles is a patron of the Red Squirrel Survival Trust and a vocal advocate on its work to protect the rodent whose future is increasingly uncertain.
A spokesman for Prince Charles said: "The red squirrel is a most cherished and iconic national species, and, as Patron of the Red Squirrel Survival Trust, The Prince of Wales keenly supports all efforts to conserve and promote their diminishing numbers.
"Where appropriate, this includes the humane and lawful control of grey squirrels as well as other measures to enhance the natural habitat of reds across the Duchy of Cornwall estate, in accordance with established estate management practices."
There are 17 red squirrel strongholds in northern England with an estimated 140,000 red squirrels left in Britain, but there are thought to be more than 2.5 million greys, according to the Forestry Commission.
Grey squirrels are an obstacle in the Government's pledge to increase woodland cover from 10% to 12% of England's land area by 2060.
They cause an estimated £10 million a year in damage to trees, the Country Land and Business Association (CLA) said.