Environmentalists are excited by the discovery of an endangered sea bird 10,000 kilometres from where it was tagged by scientists off Cape York in far north Queensland more than 20 years ago.

The Environmental Protection Agency (EPA) says the herald petrel that was tagged on Raine Island in 1984 has been seen off the coast of Mauritius.

Not much is known about the rare birds and Raine Island was thought to be their only nesting spot.

The EPA’s Dr Col Limpus says the discovery means they have much longer life spans than first thought and they nest at more than one site.

“It perhaps gives us some hope that there may be more birds in the population than we thought, if they’re moving from one island to another then we may not just have the few at Raine Island that we thought,” he said.