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A Rat-Free Palmyra?

Palmyra Restoration Project Completed

"The methods developed for and proven at Palmyra set a precedent for subsequent efforts to restore other tropical islands."

Bill Waldman, Executive Director, Island Conservation

This past summer, Nature Conservancy staff members on Palmyra were heartened when they heard the poignant cries  of the wedge-tailed shearwater, a ground-nesting seabird that had not bred on the atoll since before the Conservancy acquired it in 2000.  

The sighting of the shearwater was one of several encouraging signs following a month-long operation to remove all black rats from the atoll.  A joint effort of the U.S. Fish & Wildlife Service, Island Conservation and The Nature Conservancy, the project was the result of several years of planning and research and the first step in a longer-term effort to restore the atoll’s ecological balance.

“Complete success cannot be confirmed until no rats have been observed on the atoll for one to two years,” said Susan White of the U.S. Fish & Wildlife Service, who oversaw the project. “But the operations were carried out safely and efficiently and were a great achievement.”

This past June a 41-person crew delivered rodenticide bait to all 25 of Palmyra’s islets. Two months later, researchers conducted the first phase of a two-year monitoring process.  After deploying hundreds of detection devices throughout the atoll, no signs of rats were found.

“Juvenile land crabs have been observed throughout the atoll,” said Suzanne Case, the Conservancy’s executive director for Hawai‘i and Palmyra.  “This is a relatively uncommon sight, as these crabs are slow-moving and one of the favorite foods of rats.”

Equally encouraging, the number of sooty tern eggs observed in nests is much greater than in recent years.  Some birds have been observed sitting on two eggs, and even abandoned eggs are unmolested by rats.

Black rats, likely introduced to the atoll during World War II, prey upon ground-nesting and tree-nesting birds, consuming eggs and chicks. Rats are also likely responsible for the absence of several species of burrow-nesting seabirds such as shearwaters and petrels that are now likely to return and breed at Palmyra. Rats compete for food with shorebirds, attack native land crabs, and eat the seeds and seedlings of native trees.

According to Bill Waldman, executive director for Island Conservation, the lessons learned at Palmyra are critical to the survival of seabirds and native species on islands around the world.  “The methods developed for and proven at Palmyra set a precedent for subsequent efforts to restore other tropical islands, protecting species in places where it might have seemed impossible before,” he said. 

The project goal was to expose every rat on the atoll to bait while mitigating impacts to native species. To protect shorebirds from potential exposure to rodenticide, the operation was conducted when the majority of shorebirds had departed to their northerly breeding grounds. Project team members also were able to successfully capture and care for bristle-thighed curlews, a rare species with a global population of only 7,000 pairs.  

Between early June and early August, 13 curlews and one Pacific golden plover were captured and cared for.  All 14 birds were safely released back to the wild.  Of the 13 curlews that were in captive care, eight have been spotted since their release, having joined flocks of non-captured birds.

 “Project partners are cautiously encouraged by daily indicators of a rat-free Palmyra,” said Case. “Sooty terns, native trees, insects, various invertebrates and crab populations all appear to be flourishing.”

For more information go to: www.protectpalmyra.org

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