An appeal has been launched on St David's Day to secure the future of Welsh Mountain Ponies in north Pembrokeshire.
There are 28 ponies across 15 different locations, including the St David's Peninsula.
National Trust Wales said the ponies are key to conservation grazing and want to increase the herd by seven.
They have a fundraising target of £2,000.
A trust spokesperson said the heathland, where the ponies graze, is a "vital habitat for a wealth of species", including ground-nesting birds, seabirds, small mammals, lizards, insects and plants.
"Without regular grazing by the ponies, the heathland would start to degrade putting this species at risk," they said.
The trust's campaign harnesses the spirit of St David himself, who said it was the "little things that make a big difference".