An Australian bird, the regent honeyeater, is at more risk of extinction than the giant panda or the Sumatran rhino according to a top environment researcher.

Once abundant across southeastern Australian, including Victorian and New South Wales, more generous estimates put the wild population at as low as 350 birds.

The Australian regent honeyeater is at extreme risk of extinction.

ANU's Bird Research Group's lead researcher Ross Crates said the longer they left the birds to fend for themselves, the harder it would be to fix.

"The message really is if we're going to save the species, we need to do it now," Mr Crates said.