Environmental DNA Test May Reveal Where Birds Flock Together, Claims Study

In a first, researchers have shown that environmental DNA (eDNA) can be used to detect the presence of an endangered bird species by collecting and analysing small amounts of water from the pools where they drink -- an advance that may lead to a better assessment of animal and bird populations in the wild.

The study, published in the journal Endangered Species Research, noted that eDNA -- which is DNA collected from environmental samples like soil, seawater, or even air rather than direct sampling from an individual organism -- can be used to detect the presence of threatened terrestrial species in an ecosystem.

The researchers, including those from the Charles Darwin University in Australia, developed a genetic probe that targets and identifies the eDNA of the endangered Gouldian finch -- a rainbow-coloured bird found in northern Australia. The researchers developed a test in which multiple copies of a species-specific probe is made to detect Gouldian finch DNA.

The technique also amplifies probes against a fragment of DNA found in the mitochondria of estrildid finches -- a family that includes masked finches, and long-tailed finches, they said. The Gouldian finches, the researchers said, often drank at waterholes in mixed flocks with the masked finches and long-tailed finches.

The research team showed that the finch eDNA could be reliably detected from 200 millilitres of water samples collected from waterholes visited by the birds in the last 48 hours. The study noted that in the waterholes with the most birds, Gouldian finch DNA could still be detected 14 days after sample collection -- regardless of whether the sample was stored at room temperature, or refrigerated.

The researchers said if the Gouldian test came negative, the eDNA test still worked -- meaning the Gouldian finches were not present at that site. "It's a much more accurate test. By having primers that pick-up other finches it tells us that the eDNA is good enough quality to be amplified," said study co-author Karen Gibb of Charles Darwin University.

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"When it worked in the real world at the waterholes, even where the water was poor quality in places -- where it was hot and looked a bit oily -- we were really excited," Gibb said.

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