Endangered Hawaiian Duck Saved From Brink of Extinction
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While the Hawaiian duck may look like a run-of-the-mill, invasive female mallard, it is actually fast approaching genetic extinction.
New research, however, suggests otherwise.
As a postdoctoral scholar at the University of California, Davis, Caitlin Wells studied the birds, which she described as “petite, buffy brown, and charismatic.”
Often found in pairs instead of large groups, the wary koloa maoli (“native duck”) are secretive and rarely associate with other animals. They can usually be found in the tall, wetland grasses and streams near the Kohala volcano on Hawaii.
The team—including scientists from UC Davis; U.S. Fish and Wildlife Service; University of Texas, El Paso; Wright State University; Oregon State University; and Hawaii’s Division of Forestry and Wildlife—analyzed 425 koloa, mallards, and hybrids from populations across the islands.
They gathered more than 3,300 genetic data points, including blood samples, from hundreds of the birds before releasing them back into the wild. Researchers also collected information from the carcasses of koloa retrieved following botulism outbreaks.
“We used a lot of tissue samples from salvaged birds that unfortunately died from those disease outbreaks,” Wells, a research scientist at Colorado State University, explained.
The largest population of koloa is on Kauai, where the team found very few hybrids. On other islands, however, all of the birds were crossbreeds or feral mallards.
This study is pivotal in the struggle to save koloa from extinction. (Photo Credit: Christopher Malachowski / Oregon State University)
Historically, koloa existed throughout the main Hawaiian islands. Unfortunately, habitat loss, predators, and unregulated hunting meant they disappeared from everywhere except Kauai and Niihau by the late 1960s.
Wildlife managers began captive breeding and release programs to re-establish the koloa. But since mallards were never removed, rapid hybridization continued.
Efforts are now underway to remove mallards from the 50th state to help preserve the genetic diversity of the endemic Hawaiian duck.
“Its recovery could be viewed as a beacon of hope for the many dozens of critically endangered birds found in the islands,” according to study co-author Andy Engilis, curator of the UC Davis Museum of Wildlife and Fish Biology.
Hybridization is a tricky issue in terms of conservation: Sometimes it threatens a unique gene pool, while other times it adds more diversity to a population.
“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.”
Previously, wildlife managers mistakenly believed that leaving koloa hybrids alone would allow them to eventually evolve back into pure ducks.
“That’s not what we found,” Wells added. “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.”
The team’s research provides insight into successful conservation management, and, fingers crossed, may one day lead to the koloa being taken off the endangered species list.
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