There are more fulmars on St Kilda than anywhere else in Britain and Ireland.
They nest at the top of the cliffs, choosing a nest site with a bit of earth and grass rather than just bare rock.
Fulmars fly with almost flat wings and are one of the best birds at gliding on air currents.
Fulmars will spit a fishy smelling oil at anything (or anyone!) that gets too close to their nest. If fulmar oil gets on your clothes, the smell stays there, no matter how often you wash them.
The fulmars were very important to the people who used to live on St Kilda. They ate them and used their oil for burning in oil lamps and for rubbing into tired muscles. They paid their rent in fulmar feathers and used their wings as a kind of brush to sweep up the ashes from the fire.