A rat was found dead on St. Paul Island in the Bering Sea. Here’s why that’s a big deal.

An intensive 10-month search for a stowaway rat that invaded the rat-free seabird paradise of St. Paul Island has come to a happy end for everyone. Except the rat.

St. Paul Island, in the Bering Sea, is home to about 480 people and is an internationally known breeding habitat for millions of seabirds, including rare migratory species.

Being rat-free is essential for the ecosystem’s survival, biologists say.

So biologists and locals felt a moment of “terror” when a Norway rat was spotted in the island’s fish processing plant last fall, said Heather Renner, a supervisory wildlife biologist with the Alaska Maritime National Wildlife Refuge.

“(St. Paul and neighboring St. George Island) are two of the last communities where there’s actually a port and vibrant community and there are not rats,” she said. “They are home to a tremendous wildlife resource.”

Rats pose a potentially devastating threat to the island’s abundant bird populations, said Lauren Divine, director of the Ecosystem Conservation Office at Aleut Community of St. Paul Island.

“Rats have such a potential to invade and change the ecosystem in a way we’d never recover from,” she said.

Seabirds laying eggs on rocks and songbirds nesting on the tundra would offer rats a buffet. Double the trouble for a pregnant female rat, the “worst case scenario,” Divine said.

So for decades, the local tribal government and state and federal agencies have partnered to keep rats off the island while maintaining a local port and fish processing.

Rats have tried -- and failed -- to slip on to St. Paul before, said Heather Renner, supervisory wildlife biologist with the Alaska Maritime National Wildlife Refuge.

At least eight rats have been caught by a “security detection program” involving traps at the harbor, she said.

The rat that somehow slipped into the fish processing plant probably arrived on a boat, officials believe.

Its presence was cause for major and immediate alarm, said Divine.

Local wildlife conservation agency and federal officials mounted an immediate and aggressive response, assembling a “strike team” that deployed baited rat traps and set up a system of wildlife cameras to track the rat’s movements.

By then, an elite team invested in killing St. Paul’s rat had become involved: There were weekly email conversations and calls, and consultations from federal scientists and an international group called Island Conservation that specializes in eradication of invasive species.

Then came a winter of frustrating near misses. Once, the rat was caught in a live trap but somehow escaped.

“It has been a wily rat,” said Renner. “Really frustrating.”

People on St. Paul spotted it at such close range they “felt like they could reach down and grab it,” Renner said.

Finally, the group decided rodenticide, which they’d hoped to avoid because of the risk to people, pets and wildlife, was needed. A person had to be specially trained to safely apply it, according to Renner.

Then on June 30, just as island kittiwake chicks were hatching and bird tourism was nearing its summer peak, a visiting birder made a discovery: The dead rat.

KUHB, the local public radio station, posted a Facebook photo of a jubilant-looking Divine holding the frozen, dead rat.

The end of the wily rat saga is cause for tempered celebration, said Renner.

“If you have one rat, you have to assume there are more,” she said.

There’s no evidence that other rats are on the island, but monitoring will continue.

“If after a few weeks or months we have no further detection we’ll feel more comfortable saying they are gone,” she said.

Keep rats off St. Paul is “a forever war,” Renner said.

Divine, the ecosystem director, said people are happy about the news and ready to work to keep St. Paul devoid of any more rodent interlopers.

“It’s definitely a deep source of pride for tribal members and community members to say we are a rat free island,” she said.