April is one of roughly 200 red wolves in a captive breeding program.

April is one of roughly 200 red wolves in a captive breeding program.

Bethany Augliere

Effort to prevent ‘coywolf’ hybrids is working, study finds

Biologists have successfully prevented coyotes from destroying the genetic integrity of red wolves, one of the world’s most endangered canines, a new study concludes. The finding comes as state and federal officials mull whether to phase out the conservation effort, which has involved sterilizing coyotes to prevent the births of wolf-coyote hybrids, as a result of concerns about cost and long-term effectiveness.

With roughly 50 animals left in the wild, red wolves (Canis rufus) live on just a single peninsula on the Atlantic coast of North Carolina. In 1973, the population dwindled to 14 wolves; the U.S. Fish and Wildlife Service (FWS) then captured the wolves to establish a captive breeding population. In 1987, biologists rereleased red wolves into the wild in North Carolina’s Alligator River National Wildlife Refuge. The fragile population now inhabits some 700,000 hectares of public and private land on the Albemarle Peninsula.

The main threat to the wolves comes from coyotes, which mate with the wolves to produce fertile “coywolf” hybrids. This genetic dilution is a recent problem; coyotes migrated into the region after the FWS biologists reintroduced the wolf. In 1999, biologists started sterilizing coyotes to prevent hybridization. The sterilizations are “not to control the coyote population size … it’s purely to keep their DNA from being passed to a red wolf offspring,” says ecologist Eric Gese of Utah State University, Logan, a lead author of the new study and a member of the panel overseeing red wolf recovery efforts. Biologists also wanted the sterile coyotes to act as “placeholders” that would occupy territory until they were kicked out by a wolf.

The 15-year sterilization program has done just that, Gese and colleagues conclude in this month’s Biological Conservation. From 1999 to 2013, red wolves displaced or killed 51 out of 182 sterile “placeholder” coyotes, and managers removed an additional 16. This led to red wolf litters outnumbering hybrid litters every year. And no “placeholder” coyote ever displaced a wolf. Without this intervention, Gese says, the purebred red wolf would likely be gone.

The study highlights a “useful and effective technique of reducing introgression of coyote genes into red wolf populations,” says Dave Mech, a wolf biologist and senior scientist with the Biological Resources Division of the U.S. Geological Survey in St. Paul, who was not involved with the research.

The question now is whether it will continue. Private landowners and North Carolina officials have complained about the impact of playing host to a protected species, and some critics have questioned whether the red wolf is actually a hybrid between coyotes and gray wolves.

Meanwhile, an independent evaluation of the red wolf program released in November 2014 by the Wildlife Management Institute (WMI) questioned whether the conservation effort can succeed. Hunting and conflicts between wolves and landowners continue to threaten the animals, it noted, and hands-on management of red wolves alongside coyotes is costly. And hopes that limiting hybridization would allow the red wolf population to grow and reclaim large swaths of territory from coyotes haven’t been fully realized.

“The future is problematic,” says biologist Douglas Smith, a project leader for the Wolf Restoration Project in Yellowstone National Park in Wyoming who served on the WMI review. “Problematic doesn’t mean there is not a road to success, but they have been stalled at around 100 wolves.”

In June 2015, FWS announced it would halt reintroducing red wolves to the wild while it assessed the program. Among other things, scientists are now trying to determine whether there is a red wolf population size that could persevere alongside the coyotes without human management, and whether there is more suitable habitat than the Albermarle Peninsula. “This is the problem wolves have everywhere: They live fine next to people, but people don’t live fine next to them,” Smith says.

Conservation groups oppose FWS stopping the red wolf management effort during the assessment and hope that the program ultimately continues. A decision is expected in 2016. 

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