Desecheo National Wildlife Refuge safe from invasive mammals after nearly 100 years.

After more than a decade of conservation intervention, Desecheo National Wildlife Refuge (NWR) is once again safe for the Threatened Higo Chumbo cactus, native seabirds, and unique lizards found nowhere else in the world.

Just one year after the final phase of an ambitious operation to rid Desecheo NWR of introduced, damaging (invasive) rats, conservation biologists have confirmed that these predators are absent from the island, and the operation was a success. This project, the largest conservation operation of its kind to date in the region, would enable the island to return to its former and rightful status: the most important seabird colony in the region. The refuge lost this status due to the presence of invasive mammals for almost a century.

Desecheo NWR was once the largest Brown Booby (Sula leucogaster) and seabird breeding colony in all the Caribbean. Its storied history includes early Western observers (circa 1878) documenting strange black clouds above this towering island 13 miles west of Puerto Rico. As those explorers neared the islands, the “clouds” came into focus, turning out to be a cacophony of tens of thousands of seabirds.

In the early 1900s, Desecheo NWR was still a major nesting ground for thousands of seabirds. Approximately 15,000 Brown Boobies, 2,000 Red-footed Boobies (Sula sula), 2,000 Brown Noddies (Anous stolidus), 1,500 Bridled Terns (Onychoprion anaethetus), and hundreds of Magnificent Frigatebirds (Fregata magnificens), Laughing Gulls (Larus atricilla), and Sooty Terns (Onychoprion fuscatus) nested here.

Unfortunately, invasive mammals, including goats and rats, began to impact Desecheo NWR early in the 20th century. Around and during the time of World War II, the island was used as an artillery range by the US Air Force. That and the invasive species’ damage to Desecheo’s ecosystem have been severe, and by the turn of the millennium, virtually no seabirds were using the refuge.

The team of conservation biologists that visited the island to confirm the presence or absence of invasive rats deployed and monitored hundreds of detection devices, including chew tags, tracking tunnels, live traps, and remote, motion-triggered cameras. Following the ten-day deployment and processing tens of thousands of remote, motion-activated camera images captured in the field, the team confirmed: no sign of rats!

“It is with great excitement that we announce this historic conservation achievement; the operations to rid Desecheo NWR of damaging invasive rats is a success,” said Susan Silander, Project Leader of the Caribbean Islands National Wildlife Refuge Complex. “For many years, in collaboration with all our partners, we have fully invested our time and spirit to successfully achieve these results for the benefit of the refuge and its native animals. We hope such efforts will serve as an example to other conservation entities doing similar types of work.

Island Conservation’s José Luis Herrera, Confirmation Monitoring Trip Leader reported that Desecheo had experienced a lot of rain this spring, which, combined with the absence of rats, allowed the team to observe an island that was thriving like they had never seen!

“It was a very exciting trip,” said Herrera. “We recorded events unlikely to occur in the presence of invasive mammals—possibly, early signs of recovery. We documented Oystercatchers nesting with two eggs, two American Kestrel fledglings, a juvenile Peregrine Falcon, large numbers of endemic and native reptiles, and up to 30 Brown Boobies foraging in the nearby waters. The island’s dry-forest plant life was blooming and fruiting throughout the island and its understory was teeming with endemic lizards and land crabs.”

The team also observed increasing numbers of Threatened Higo Chumbo cactus—some flowering and fruiting. Desecheo’s recovery is critically important for this rare cactus because it its range is extremely limited with only two natural populations outside of the refuge. The removal of invasive rats from Desecheo offers hope for the recovery of this vulnerable species.

The excitement over Desecheo’s new, rat-free status is accentuated by the recent project being the site’s second rat eradication attempt. “It is tremendously satisfying to call this project a success,” said Island Conservation’s 2016 Eradication Operation Project Manager David Will. “This demonstrates that our work with key partners and the island restoration community to better understand, improve, and publish best practices to increase tropical rodent eradication success is paying off. Hopefully this is a positive sign for things to come—namely an increasing global success rate for similar eradications in the tropics.”

David Viker, Chief of the National Wildlife Refuge System for the Southeast Region, emphasized that “the success of the project was a win for cooperative conservation and an example of how, with perseverance, we can achieve goals to restore invaluable wildlife habitat.”

“Efforts are under way to secure funding to begin to attract, and perhaps translocate seabirds to the refuge,” said Herrera. “Hope springs eternal; in a few short seabird generations, we may once again observe the black clouds of thousands of seabirds shadowing this special island.”
***ENDS***

Contacts

Susan Silander, US Fish and Wildlife Service, susan_silander@fws.gov; (787) 851-7258 x 306
Heath Packard, Island Conservation, heath.packard@islandconservation.org; +1.360.584.3051

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Refuge Facts

• Established: 1976
• Acres: 358
• Location: the island is located 13 miles from the west coast of Puerto Rico
• Administered under Caribbean Islands NWR office

Natural History

• Desecheo NWR has seen many stewards over the years, including Spain, Puerto Rico, the US Military (military training activities), the National Institute of Health (N.I.H.) for medical research, and the US Fish and Wildlife Service.
• At one time, the largest Brown Booby nesting colony in the world. Today, little seabird nesting takes place on the island.
• The native forest (which includes the Threatened Higo Chumbo cactus) has been severely degraded by introduced rats, and goats.

Refuge Objectives

• To restore and protect historic seabird colonies and natural island ecosystems.

Location

• 13 Miles west of Puerto Rico

Terrain

• Much of the rocky terrain is covered by a native forest adapted to a dry climate. Large Gumbo Limbo trees are common in interior valleys while a variety of cactus species, including the Endangered threatened Higo Chumbo, form a part of the thorny scrub vegetation covering the steep coastal slopes.

About the Conservation Partnership

Island Conservation, a non-profit organization dedicated to preventing extinctions by removing invasive species from islands, is a partner with the US Fish and Wildlife Service in the plan to restore Desecheo Island by removing invasive rats.

The US Fish and Wildlife Service is the principal federal agency responsible for conserving, protecting, and enhancing fish, wildlife, and plants and their habitats for the continuing benefit of the American people. Please visit the Service’s website at http://www.fws.gov/caribbean/refuges.

Funding for this project has been provided by the US Fish and Wildlife Service and Island Conservation through many private donors, including the David and Lucile Packard Foundation, National Fish and Wildlife Foundation, US Federal wildlife conservation grants, and through important donations made by Bell Laboratories and Tomcat.

Featured Image
Desecheo National Wildlife Refuge, Puerto Rico
Photo by: Claudio Uribe/Island Conservation