Endangered birds leave genetic clues in their drinking water

EDNA proving a powerful tool that could aid conservation.

Australian researchers have worked out how to trace an endangered bird species by analysing water from its drinking holes.

Using environmental DNA (EDNA), a team led by Karen Gibb from Charles Darwin University identified the movements of the stunning rainbowcoloured Gouldian finch (Erythrura gouldiae), a species native to tropical savanna woodlands in Australia’s north.

EDNA is used to detect the locations and numbers of rare and threatened species from water samples and to date has mostly been applied to freshwater animals.

Gibbs and team, including colleagues from the University of Western Australia, saw an opportunity to track the Gouldian finch using water sample analysis, as it needs to drink several times a day.

To do this, they developed a test that can identify estrildid finches from a fragment of mitochondrial DNA, and a probe specifically designed to detect Gouldian finch DNA.

This was necessary to distinguish the colourful finches from masked finches (Poephila personata) and long-tailed finches (P. acuticauda) – other estrildid species that often flock together at the same waterholes.

“It’s a much more accurate test,” says Gibb. “By having primers that pick up other finches it tells us the EDNA is good enough quality to be amplified. If the Gouldian test is then negative, we can be confident that the EDNA test worked, but there just weren’t Gouldian finches at that site.”

First, they piloted the method in wildlife park aviaries before a series of field trials at the Yinberrie Hills in the Northern Territory, where scientists and rangers had good observation data to validate the tests.

With a 200-millilitre water sample they could successfully detect Gouldian finch EDNA from waterholes the birds had visited in the previous 48 hours, and where there were lots of birds, it was still measurable from the samples two weeks later.

The study is published in the journal Endangered Species Research.