Rat Eradication

A successful rat eradication program on Wake Island was reported last month (April 2026) by Oceanographic and The Garden Island: Hawaii News (links below). Agencies measure success by no sightings or evidence of rat habitation over a year after conclusion of the operation and by a steady and marked increase in nesting birds and their young, as well as other species including geckos, spiders, and hermit crabs. Another revival is that of native Pisonia seedlings, a type of tree/vine, which may have consequences for the birds down the line.

The escalation of U.S.-China competition in the Indo-Pacific has brought heightened military attention and funding to Wake Island for its unique mid-Pacific advantages, and rats do not fit into the plan. The rodents not only ravage the flora and fauna, but they invade facilities and living quarters, spread disease, and gnaw through cables and wires, often interfering with airfield operations and communications. As renovation and construction ramped up over recent years, so did the commitment to rat eradication.

Two species of rats – Asian rat and Pacific rat – have flourished on Wake for hundreds of years, brought by early Polynesian seafarers during centuries of Pacific migrations. Humans judged the atoll uninhabitable, but rats remained and the ecosystem adjusted over generations. In the 20^th century humans did establish a presence on Wake and have faced the rat challenge for the last ninety years, trapping and shooting, bringing in cats, and government-sponsored eradication attempts. A large-scale program was beginning when I visited Wake in 2011 (it failed). See my post Try, Try Again.

In my 2023 post I noted a news release about development and testing of drone technology to distribute rat poison on Wake Island, unaware that this was during larger and longer effort to banish the Wake rats finally. While the press releases last month named Island Conservation, the U.S. Fish and Wildlife Service, USDA, and the USAF 611^th Civil Engineering Squadron as the collaborative group that completed rat eradication on Wake, other agencies had been involved in the process since 2020. The Center for Environmental Management of Military Lands, (CEMML) was an important early partner that evaluated reasons why previous efforts had failed, from flaws in baiting strategy to inefficient food waste management and lack of buy-in by the full community residing on Wake. A two-year pile-up of trash at the dump exacerbated the current problem. With waste removal, tightened controls over food management, the cooperation of local leadership, and a commitment to see the process through, the eradication program showed strong promise. While helicopters dropped pesticides over known rat colonies, other poison rat traps were set strategically ensuring minimal danger to other wildlife and that none entered water. Thermal cameras spotted survivors as targets for night shooting expeditions (a technically enhanced version of a long-favored pastime enjoyed by competitive residents and visitors), and trained rat dogs dispatched the remainder. Then it was time to wait and watch.

The Island Conservation group – an environmental nonprofit – now confirms the rats gone and a substantial increase in sixteen types of nesting seabirds, eggs, and fledglings, as well as the revival of other native species. Island Conservation also notes the emergence of thousands of Pisoniatree seedlings across the atoll where rats once devoured the sticky seeds. Having never heard of this tree, I looked it up and found that Pisonia grandis is known as “bird catcher” for reasons that soon may become painfully clear on rat-free Wake. Pisonia seed pods are long and covered with mucous and hooks and form in large bunches in the branches of the tree. The Pisonia tree flowers twice a year, coinciding with high periods of seabird traffic. Breeding seabirds, drawn to nest in the branches, often find that when their eggs hatch, the young become trapped in the sticky seed bunches and die.

Removing the invasive but long-adapted rat species from an isolated ecosystem like Wake Island allows the recovery of other native and migratory species. However, the rebalancing of the ecosystem – including such aspects as the proliferation of Pisonia trees may have unintended, detrimental effects on the very nesting birds and others that the project intended to protect. Nature does not pick winners.

Rat eradication sparks record-breaking seabird breeding in Hawai’i

Nesting native seabirds thrive after invasive rats are eradicated – The Garden Island