Australia is known for its rich bird life but the cost of colonisation on the country's birds is becoming clearer.

A new study has found that one species of bird and five sub-species that were listed as critically endangered a decade ago, actually vanished between 20 and 70 years ago.

Every decade, experts review the status of Australia's birds based on the observations of birdwatchers around the country.

There has been no sign of the six types of birds in trouble.

"We were worried about these birds when we last reviewed their status 10 years ago," Professor Stephen Garnett from Charles Darwin University said.

"Sadly, no sign of them has turned up in the last decade.

"A number have been targeted searches for them in just the right habitat for quite long periods of time but have still not found them."

The birds now thought to be extinct are:

- the white-breasted white-eye from Norfolk Island

- a type of pied currawong from the Grampians

- a type of thick-billed grass wren from near Alice Springs

- the hooded robin from the Tiwi Islands

- the spotted quail thrush from near Adelaide

- the southern star finch from the east coast of Australia

"It's about a 25 per cent increase in the number of types of birds that have gone extinct since European settlement in Australia," Professor Garnett said.

The researchers will recommend the birds be internationally listed as extinct.