In a Winn-Dixie strip mall just off the Overseas Highway, a storage room at the National Key Deer Refuge visitor center has become the first stop in an expanding campaign against a ghastly screwworm infecting the planet’s last herd.
The refuge’s small staff crowded the room, loading tinfoil trays with white bread slathered in orange blossom honey and injected with a potent antiparasitic. A ranger filled squirt bottles with purple paint while another packed Ziploc bags with chopped fruit to both lure and reward deer for taking the bitter medicine. Volunteers and biologists hustle in and out, grabbing rubber gloves to protect themselves from the drug as they head out on sorties into deer habitat.
Up the road, a U.S. Department of Agriculture command center at the airport in Marathon is undertaking something not done in the Southeastern U.S. in half a century: eradication of the New World screwworm.
With the number of deer killed by the screwworm outbreak reaching 114 as of Tuesday, the entomologists, GIS experts, vets and biologists fighting the outbreak ramped up their efforts this week. The assault is simple in theory — attack on two fronts by protecting the deer with a prophylactic drug and eliminating the flies with squadrons of infertile breeding partners — but complicated in execution. Biologists say the deer are susceptible to capture myopathy, meaning they can literally die of fear, so tracking and treating them has been tricky. Such a large-scale effort has never been undertaken on the herd. And fighting screwworm across wetlands and a dense pine rockland — the largest tract in the U.S. outside Everglades National Park — is entirely new territory.
“It’s not something we ever expected,” said refuge biologist Adam Emerick, who first noticed bucks turning up with grisly wounds in mid September and, after wondering whether something might be amiss, collected four samples to test for parasites.
Over the weekend, the refuge’s staff trained 50 volunteers on how to lure and feed the deer — something strictly forbidden over the years in an attempt to keep the herd wild, said park ranger Kristie Killam. So far, 335 have been treated in a herd estimated at about 1,000. Monday also marked the first day since officials began documenting the outbreak that no deer were euthanized, a rare bit of good news, said U.S. Fish and Wildlife spokesman Kevin Lowry.
Entomologists have also begun releasing sterile screwworms to mate with wild flies. They plan on releasing about 2.7 million each week, produced at a Panamanian lab jointly run with the USDA.
Because the screwworms haven’t appeared in the U.S. in so long, entomologists are identifying hotspots based on conditions in other counties, said Scott Peterich, a wildlife mitigation specialist with the Florida Forest Service who is pitching in to provide mapping expertise. But the mix of habitat in the Keys is proving challenging.
“They say go there, but then we find out there’s mangrove and water and we can’t go there,” Peterich said.
On Monday, Killam, Emerick and two other biologists searched spots favored by the deer — an overgrown coconut farm now used to house refuge interns and still called the Nut Farm and along Key Deer Boulevard. The deer readily ate the bread after being lured with the fruit. Staffers continue to wrestle with how to reach more reclusive wild deer deeper in the refuge.
The drug, doramectin, needs to be re-administered every seven days. For tamer deer, volunteers and staffers are marking deer they feed with a different color non-toxic paint to indicate what day they were treated. The deer don’t always cooperate: On Monday, a doe and a young buck tried to lick off the paint. They’re trying to come up with a better alternative, which can be tricky in the tightly regulated refuge that also caused some locals to complain the staff reacted too slowly to the initial outbreak.
“People asked what took you so long once this was diagnosed. But we have 23 endangered species. We have to balance protection and making sure we weren’t hurting other animals,” Killam said. “We wanted to make sure we didn’t make a bigger problem.”
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