Why an Alaskan Island Is Using Peanut Butter and Blacklight to Find a Rat That May Not Exist

On an island of windswept tundra in the Bering Sea, hundreds of miles from mainland Alaska, a resident sitting outside his home saw — well, did they see? They were pretty sure they did.

A rat.

The alleged sighting would not have attracted attention in many places around the world, but it caused a stir on St. Paul Island, part of the Pribilof Islands. This archipelago is a bird paradise that is sometimes called the ‘Galapagos of the North’ because of its diverse wildlife.

That’s because rats that hide on ships can quickly spread to and overrun remote islands, devastating bird populations by eating eggs, chicks or even adults, and upending once vibrant ecosystems.

Shortly after receiving the resident’s report in June, animal control officers arrived at the apartment complex and crawled through nearby grasses, around the building, and under the porch, looking for tracks, chew marks, or feces. They set up traps with peanut butter and set up trail cameras to capture any confirmation of the rat’s existence, but so far they have found no evidence.

“We know because we’ve seen this on other islands and in other locations in Alaska and around the world that rats completely decimate seabird colonies, so the community would never take the threat lightly,” said Lauren Divine, director of the Aleut Community of St. Paul Island’s Ecosystem Protection Office.

The scare on St. Paul Island is the latest development in long-standing efforts to eradicate or keep non-native rats from some of the most remote, yet ecologically diverse islands in Alaska and around the world.

According to the U.S. Fish and Wildlife Service, rodents have been successfully removed from hundreds of islands worldwide, including an island in Alaska’s Aleutian Islands chain formerly known as “Rat Island.”

Ultraviolet ‘chewing’ blocks

But such efforts can take years and cost millions of dollars, which is why prevention is seen as the best defense.

Around developed areas of St. Paul, officials have set up blocks of wax — “chew blocks” — designed to capture any telltale incisor bites. Some of the blocks are made of ultraviolet material, allowing inspectors to use blacklights to look for glowing feces.

They have also asked residents to be on the lookout for rodents and are seeking permission from the U.S. Department of Agriculture to bring a dog to the island to sniff out rats. Dogs are banned on the Pribilofs to protect fur seals.

No further traces have been found since a rat sighting was reported last summer, but the hunting and increased vigilance are likely to continue for months to come.

Divine compared the search to looking for a needle in a haystack, “without knowing if the needle even exists.”

The community of about 350 people, clustered on the southern tip of a treeless island characterized by rolling hills, fringed by cliffs and battered by storms, has long had a rodent-monitoring program, including rat traps near the airport and at developed waterfront areas where ships dock. These traps are designed to detect or kill any rats that might be present.

Still, it took nearly a year to capture the last known rat on St. Paul, which was believed to have jumped from a boat. He was found dead in 2019 after evading initial community defenses. That underscores why even an unsubstantiated sighting is taken so seriously, Divine said.

Fish and Wildlife wants to eradicate rodents on four islands

The U.S. Fish and Wildlife Service is planning an environmental study to assess the eradication of potentially tens of thousands of rats on four uninhabited islands in the remote, volcano-torn Aleutian Islands, hundreds of miles southwest of St. Paul. More than 10 million seabirds of various species nest in the Aleutians.

The diversity and abundance of breeding birds on islands with established, non-native rat populations is remarkably low, the agency said. Carcasses of dwarf auks and crested auks, known for their noisy nesting colonies in rocky areas, have been found in rat food dumps on Kiska Island, one of four islands where rat footprints have been spotted on the wet, sandy shoreline.

If the agency moves ahead, it could take five years for the first project to get underway. And given the intensive planning, testing and research required for each island, it could take decades to complete them all, said Stacey Buckelew, an invasive species biologist with the Alaska Maritime National Wildlife Refuge.

But such efforts are important steps to help seabirds already struggling from stresses including climate change, Buckelew said. The success of what was long called Rat Island, an area in the Aleutian Islands about half the size of Manhattan, shows how effective eradication programs can be. Rats are believed to have first arrived on a Japanese shipwreck in the late 18th century.

Fur traders introduced Arctic foxes over the next century. The foxes were exterminated in 1984, but it was nearly a quarter century later that wildlife managers and conservation groups killed the rats by dropping poison pellets from helicopters. Those involved said the island, without breeding seabirds, was eerily quiet compared to the cacophony of other rat-free islands, and it even smelled different.

Since the rat eradication, researchers have found that native birds benefit, and have even documented species that were thought to have been wiped out by rats. The island is once again known by the name originally given by the Unangan people, who were native to the Aleutians: Hawadax. Researchers have found tufted puffins, which burrow into cliff edges and cannot defend themselves against rats or foxes, or against the nests of eagles and falcons.

During pre-eradication surveys, researchers didn’t hear song sparrows, but during a 2013 survey, their sounds were nearly constant, Buckelew said at the time.

Donald Lyons, director of conservation at the National Audubon Society’s Seabird Institute, described being on the Pribilof Islands and watching the evening clouds of auks return to their colonies. “There were tens of thousands, hundreds of thousands, maybe millions of birds in the sky at any given time.”

He said officials were right to take the alleged rat sighting in St. Paul so seriously. He praised the mostly Alaska Native communities in the Pribilofs for their efforts to keep invasive species at bay.

“It’s just the abundance of wildlife that we hear stories about or read historical accounts about, but in modern times we rarely see,” he said. “And so it’s really a place where I’ve felt the wonder, the spectacle of nature.”