Puffins left Ramsey Island over a hundred years ago, when rats from a sinking ship infested it.
The rats destroyed the puffins' nests and ate their eggs, so the puffins fled the tiny island, west of Wales.
But now the rats have gone and bird protection charity the RSPB is using a sound system to try to persuade the birds to return.
The solar-powered sound system plays a recording of the puffins' call on a loop, to trick the birds back ashore.
Conservationists are also trying to encourage more puffins ashore by placing fake 'colonies' of dummy birds in conspicuous places, to make it look like there are puffins in residence already.