The Unlikely Comeback Story of a Once-Extinct Tropical Bird

The Guam kingfisher (Todiramphus cinnamominus), last seen in the wild in 1988, is making a comeback. Thanks to years of dedication and the steadfast efforts of the Sihek Recovery Program team, Guam kingfishers have been reintroduced to the wild—not yet in Guam itself, but on Palmyra Atoll, an incorporated U.S. territory. Guam kingfishers are called “sihek” in CHamoru, the language of the Indigenous people of the Mariana Islands, which include Guam, an organized, unincorporated U.S. territory. These colorful, medium-sized birds, once abundant in Guam’s limestone forests, went extinct in the wild due to predation by an invasive species. Read on to discover what contributed to the Guam kingfisher’s demise and how conservationists are reviving the bird population.

Why Did the Guam Kingfisher Go Extinct in the Wild?

Scientists estimate that over 99% of all animal species that have ever lived on Earth are now extinct. While that is a daunting figure, extinction is a part of life. From natural selection to mass extinction events, species either adapt and evolve or fade away. Extinction can be a catalyst for positive change, allowing remaining species to thrive and diversify. However, the extinction of the Guam kingfisher was put into motion with the introduction of the brown tree snake (Boiga irregularis) in the 1940s.

Presumed to have arrived as stowaways on cargo ships and/or aircraft returning from the South Pacific during and after World War II, predation by brown tree snakes decimated Guam’s sihek population. These mildly venomous, aggressive snakes also dealt a blow to most of the island’s native bird and lizard populations. The obliteration of these pollinators caused the decline of native plant species as well.

In the late 1980s, once it became apparent that the sihek were losing their battle with the snakes, 29 kingfishers were rescued by the Guam Department of Agriculture in conjunction with the Association of Zoos and Aquariums. An ex-situ care program was established for the species, which is now responsible for 127 adult sihek across 25 institutions. The newly released birds were plucked from these captive breeding programs. The Brookfield Zoo (Chicago), Cincinnati Zoo & Botanical Garden, Disney’s Animal Kingdom, U.S. National Aviary (Pittsburgh), and Sedgwick County Zoo (Wichita, Kansas) were directly involved with breeding the sihek that were released on Palmyra Atoll in the South Pacific Ocean in late 2024.

How Was the Guam Kingfisher Reintroduced to the Wild?

On August 28, 2024, four female and five male sihek bred in captivity journeyed from the Sedgwick County Zoo to The Nature Conservancy’s Cooper Island Nature Preserve, located within the Palmyra Atoll National Wildlife Refuge. Upon arrival, the birds were placed in temporary aviaries. While adjusting to their new home, the birds were observed closely and fed daily. To allow for continued monitoring, each bird was fitted with a radio tracker. Six birds were released into the wild on September 23, 2024, with the remaining three released shortly thereafter.

Dr. John Ewen, the Chairman of the Sihek Recovery Program team, wants people to understand that the release of the Guam kingfisher back into the wild is the result of decades of dedication, study, and work. Ewen, a professor at the Zoological Society of London’s Institute of Zoology, says of the release, “This is a momentous day that has been decades in the making.” Ewen marvels at the idea that a group of committed individuals, working tirelessly, “…has the power to protect species and take huge steps in bringing them back from the very brink of extinction.”

To safeguard the birds and the decades of work and study they represent, Palmyra Atoll was purposefully chosen for its relatively predator-free environment. Even so, the Nature Conservancy and its partners spent years restoring the atoll’s tropical forests and eradicating invasive species before the birds’ release. These efforts created a safe habitat for the sihek to re-establish a breeding population, offering them their best shot at surviving and potentially being reintroduced to Guam. 

What Is the Future of the Guam Kingfisher?

What does the future hold for the Guam kingfisher? At present, their fate is up in the air. The release of sihek on Palmyra Atoll is a step toward releasing these colorful birds in other locations. However, there is still much work to be done before these stunning birds can return to Guam.

After nearly four decades of existing solely in captivity, scientists are monitoring the newly wild sihek population to study how these birds are adjusting to their freedom. Initial reports from the Palmyra Atoll indicate that all is well. Newly wild pairs of sihek have mated and produced eggs. This suggests that the birds are not just adapting to but also thriving in their new environment. The Sihek Recovery Program plans to release nine birds each year, with the goal of establishing 10 breeding pairs on Palmyra Atoll. These birds and their offspring will help inform future release and monitoring methods, as well as determine the level of human intervention needed to support wild populations.

The long-term plan is to repatriate the sihek to Guam. However, the return of the sihek to their native range is several years away, at best. The greatest obstacle to their return is the continued existence of the brown tree snake on the island. While completely eradicating the species would be ideal, it is unlikely due to their widespread presence and lack of natural predators. As such, efforts are underway to curtail the island’s brown tree snake population. Hopefully, one day, the Sihek will call Guam home again.