Efforts to preserve endangered Hawaiian duck's genetic diversity working, study finds

Nov. 18 (UPI) — An analysis suggests the genetic diversity of an endangered duck species in Hawaii has benefited from conservation efforts aimed at protecting the native bird.

The koloa is the only endemic duck still living on the main Hawaiian Islands, but decades of interbreeding feral mallards threatened to erase the duck’s genetic heritage.

New research, however, showed the koloa’s genetic diversity is greater than expected. The findings, published Monday in the journal Molecular Ecology, suggests conservation efforts aimed at protect the endangered duck are working.

“The fact that the koloa on Kauai are pure and have a lot of genetic variation are two really positive things that came out of this study,” lead study author Caitlin Wells, a research scientist at Colorado State University, said in a news release.

Wells, who described the koloa as a “petite, buffy brown and charismatic duck,” conducted the research while a postdoctoral scholar at the University of California, Davis.

Though scientists found only hybrids and feral mallards on many of the islands where the koloa used to reign, researchers documented a large koloa population on Kauai, the oldest of Hawaii’s main islands. Scientists found very few hybrids living on Kauai.

Though once abundant throughout the islands, habitat loss, predation by invasive species and unregulated hunting left the koloa relegated to Kauai and Niihau by the end of the 1960s. Efforts to reintroduce the duck via captive breeding programs were compromised by hybridization with feral mallards.

For the new study, scientists collected and analyzed genetic samples from 425 koloa, mallards and hybrids from the main Hawaiian islands.

Though researchers found the endangered species’ genetic diversity is high, hybridization remains prominent on three of the four main islands. Previously, scientists theorized that breeding programs would eventually dilute mallard to DNA to the point of disappearance.

“That’s not what we found,” Wells said. “If you don’t have pure koloa parents that outnumber the feral mallards, you’re not going to get any decreases in those hybrid proportions.”

Still, the new research suggests conservation programs are working to preserve the species.

“Its recovery could be viewed as a beacon of hope for the many dozens of critically endangered birds found in the islands,” said study co-author Andy Engilis, curator of the UC Davis Museum of Wildlife and Fish Biology.

Wells estimates tweaks can be made to conservation efforts to reintroduce and protect the DNA of pure koloas on islands besides Kauai.

“But here’s a case where we have enough individuals with enough genetic variation in the koloa, and we’ve also genetically identified the hybridizing species,” Wells said. “It seems very clear that we can separate those going forward.”

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