Research into the genetic makeup of the critically endangered regent honeyeater has shows the animal's best chance at survival is through the protection of its rapidly disappearing habitat, a new study has found.
Researchers from The Australian National University used DNA samples taken from specimens stored in museums around the world, some dating back as far as the 1800s, to study the genetic impact of severe population decline on the birds.
Ross Crates and George Olah from the Difficult Bird Research Group were involved in the study, published in late October, and said while the species were common less than 60 years ago, they are now considered critically endangered with as few as 250 left in the wild.
The team compared the genetic makeup of the species from a time it was abundant and widespread, to that of today's population.
The birds can be found anywhere from northern Victoria to southern Queensland, and according to Far South Coast Birdwatchers' member Barbara Jones said the group's database of sightings lists five over the last 18 years, the last being at Kalaru in January last year, just months before a bushfire ripped through the bush.
"The 2009 sighting was exciting because it stayed for five days in a native garden," Ms Jones said.
Dr Crates said the rapid decline in numbers has been due to widespread loss of breeding habitat caused by land clearing, as well as increased competition for access to the remaining habitat with larger species.
"Birds in the north of the range are closely related to both their near neighbours and birds in the south of the range," Dr Crates said.
"This strongly suggests that small numbers of birds are travelling long distances to breed with each other."
"Regent honeyeaters can travel hundreds of kilometres to find blossom nectar to feed on. We don't know where they will turn up and breed from one year to the next.
"If we are going to save this species from extinction, we need to know if there is anything we can do to help maintain genetic diversity in the remaining population."
Despite the small numbers of birds left in the wild, the researchers found little genetic diversity has been lost over time.
"The good news is the birds' long-distance movements are naturally helping to maintain genetic diversity in the population," Dr Crates said.
"The bad news is this means there's little we can actually do in terms of conservation action to help manage their genetic makeup.
"It means our best chance of saving regent honeyeaters from extinction is by protecting remaining breeding habitat, restoring as much lost breeding habitat as possible and protecting nests from predators."
Named after the striking yellow-and-black plumage, the species were once regular visitors as far north as Rockhampton, west to the Riverina region of New South Wales, and south to the suburbs of Melbourne.
According to not-for-profit conservation group BirdLife Australia, who offered its own collected blood samples for the study, the loss of habitat has allowed encouraged more aggressive species of honeyeaters, such as Noisy Miners and Red Wattlebirds, to proliferate.
"When populations become small and isolated, genetic diversity can be lost, reducing the survival of the remaining individuals. In some species, this can severely impact the chances of population recovery," Dr Olah said.