Complex sentence: Seals are plentiful along its shores and are sometimes found inland during the breeding season, while the western cliffs are the site of colonies of terns, guillemots, fulmars and eider ducks.
Split into simpler sentences: Seals are plentiful along its shores and are sometimes found inland during the breeding season. The western cliffs are the site of colonies of terns, guillemots, fulmars and eider ducks.