A flock of 350 sheep are being employed to help protect Brighton butterflies.
The sheep are based on rare chalk grassland on the South Downs near Brighton.
Phillippa Morrison-Price, South Downs National Park ranger, said: “Chalk grassland is one of the most endangered habitats in the country and vital to the survival of wildlife such as the chalk hill blue and Brown Argus butterflies.
“But it only exists because of the grazing that's taken place here over thousands of years.
“Reintroducing grazing animals, like these sheep, is vital for the survival of the grassland and the butterflies that need it to thrive.
“The benefits of this work will be seen much further too. The South Downs' chalk downland is also relied on by more than a million people in and around the national park for clean drinking water and tens of millions of people as a valuable green space.”
The work contributes to wider plans to safeguard and enhance endangered chalk downland led by the South Downs National Park Authority.
The Veolia Environmental Trust has also awarded a grant of £40,000 through the Landfill Communities Fund.
This is being used to help improve chalk grassland near Saddlescombe Farm, Brighton, where rare and threatened butterfly species can still be found.
The funding means that newly improved grassland on the edge of Waterhall Golf Club will join up with grassland already managed by Brighton and Hove City Council - increasing the area the butterflies can call home by 50%.