Sightings of magpies, laughing kookaburras and willie wagtails are on the decline in some regions, a report tracking the health of Australia's bird populations has found.

The State of Australia's Birds Report, published by Birdlife Australia, analysed data collected in more than 400,000 surveys across the country, the majority done by bird-loving volunteers.

Editor of Australian Birdlife Sean Dooley said the decline of common birds in parts of Australia was a surprise to researchers.

He said while predators including cats, habitat loss and even changes in climate might be to blame, more research was needed before certain species became endangered.

"The stuff that Birdlife Australia has come out with is showing is that a lot of birds that we assumed were really common and sailing along quite fine are showing significant declines," he told 774 ABC Melbourne.

Magpies have declined significantly on the east coast, a new report shows. ( Supplied: Birdlife Australia, Dean Ingwersen )

"While they're still not endangered, it's basically the first step to them becoming endangered, so we really need to use this as a wake-up call and start looking at what we're doing across landscapes to try and figure out what's going on."

Of Australia's 137 terrestrial bird species, only 10 per cent showed a "consistent overall trend" the report found, with most birds, including magpies and willie wagtails, appeared to be declining in some regions, while increasing in others.

"Both species occur across most of the continent and show a mix of increases, decreases, variability and stability in different regions," the report said.

"It is notable that of these two species, only the Australian magpie showed a consistent pattern over time in one region — its reporting rate declined significantly in the east coast during each time period."

Sightings of willie wagtails had been decreasing on the east coast and eastern Mallee, the report found.

Eastern Mallee birds declined, began recovering, and then declined again, the surveys found. ( BirdLife Victoria )

The report also found that overall there were fewer sightings of 22 out of 39 Mallee woodland-dependent species.

More than 36,000 standardised surveys had been undertaken in the area, showing the number of birds spotted had dropped sharply between 2001 and 2006, before recovering up until 2011, when they began dropping again.

"For areas like the Mallee, we've got big national parks, so theoretically they should be doing well," Mr Dooley said.

"We know that there are things that are effecting threatened species like too many fires and things like that - inappropriate fire regimes - we now have to figure out whether that is effecting those common Mallee birds as well."

There was a near 40 per cent decrease in the average reporting rate for laughing kookaburras across south-east Australia, an area which included Melbourne, Sydney, Brisbane and Adelaide, the report found.

Underlying cause of bird declines unknown

The Eastern curlew, a migratory shorebird that has recently been declared critically endangered. ( Supplied: Birdlife Australia, Dean Ingwersen )

Bird of prey also showed troubling levels of declines in sightings, the report found, with "significant decreases in sightings for twelve of 20 arid zone carnivores".

The report said that the Southern boobook and the tawny frogmouth owls both showed significant declines in all but one region.

"This is cause for concern and further investigation is needed to understand the factors that are driving this consistent decline across regions," the report said.

Mr Dooley said it was unclear what was causing the decline in bird numbers.

"Cats may be an issue for the smaller birds, who knows. There's a decline in top predators across the entire arid zone. Maybe the cats are out-competing the predators for prey - birds like eagles and goshalks," he said.

BirdLife Australia said there were significant decreases in sightings for 12 of 20 arid zone predator birds. ( BirdLife Australia )

"It could be habitat loss, it could be change in climate; we don't actually know at this stage. All we know is that we've got this early warning signal that a lot of the birds we assumed were quite common are starting to disappear.

"Birds are the top predator for a lot of ecosystems and if it's failing at the top, then it means the whole system could be in crisis."

The data for the report has been collected by volunteers since 1998, amassing over 14 million records in more than 900,000 surveys, 427,000 of these forming the basis for the indices, the first of which was published in 2003, according to Birdlife Australia.

Mr Dooley said a wildlife survey of this scale had never been done in Australia before.

"It's taking an approach like we do with the stock exchange, rather than looking at an individual species and saying that's not doing well," Mr Dooley said.

"They're taking indices based on hundreds of thousands of surveys by thousands of volunteers and researchers over the last 15 years to give a trend of what's happening to different groups of birds right across Australia.

"The surveys have been going into the data base and the boffins at BirdLife Australia have been crunching the numbers and coming up with all these trends across the country in different regions of different groups of birds."

The report was the result of partnerships with the Federal Department of Environment, National Environment Research Program, Charles Darwin University, Australian National University, the Environmental Resources Information Network and the Melbourne Museum, Birdlife Australia said.