Guam kingfisher may soon return to the wild after 30 years away
Once extinct in the wild, the California condor now soars across the western United States thanks to successful breeding in captivity that allowed for its subsequent reintroduction into the wild. Now, a dedicated team is ready to do the same for the bright red and blue Guam Kingfisher. Endemic to Guam and extinct on the island since 1988, these birds may soon be free-flying on a Pacific island more than 3,000 miles from their native home.
“This is the long overdue and much needed first step,” says Suzanne Medina, a wildlife biologist with the Guam Department of Agriculture, Division of Aquatic and Wildlife Resources, who is helping lead the kingfisher’s recovery. “I feel very optimistic.”
As with most native bird species on Guam, in the 1980s the kingfisher was wiped out by invasive brown tree snakes, which were introduced to American territory shortly after World War II, creating a “silent forest” devoid of birdsong. The Guam kingfisher, known as Sihek in the native Chamorro language, was spared from extinction when biologists brought the remaining 29 birds into captivity. Today, nearly 140 Sihek live in 25 facilities around the world, but their survival depends on a successful reintroduction into the wild.
“Bringing them back into the wild, but also growing that captive population, are two things that need to happen for the Guam Kingfisher to persist,” says John Ewen, conservation biologist at the Zoological Society of London and a member of the team at Sihek’s recovery. .
Experts say space is one of the main limitations to increasing the number of captive Sihek. Due to the species’ inherent aggressiveness towards each other, birds are kept in separate enclosures – sometimes even in different buildings – unless they are actively breeding. On top of that, the Sihek suffer from inbreeding due to their depressed numbers. Since the population declined so rapidly and only 16 of the 29 rescued birds raised young, the recovery team must carefully plan breeding to maximize the genetic diversity of the species. Even with strict management, inbreeding has caused a declining lifespan and reproductive success of Sihek, increasing their risk of extinction. Expanding chick production – with a much-needed boost from wild birds after a successful introduction – is the species’ best chance for survival.
Ideally, biologists would reintroduce the Sihek to their native forests in Guam. But Guam still cannot sustain the wild Sihek due to the unyielding presence of the brown tree snake, despite extensive eradication efforts, including dropping poison mice from airplanes, which helped reduce the snake population. “They’re the bird of Guam, so it’s very sad that we can’t put them back there,” Ewen says. Fortunately, the Endangered Species Act allows listed species to be introduced into new areas if their current habitat is too degraded to support them.
An official recovery team formed in 2020 to search for the Sihek’s potential new home. Cocos Island, a small island just a mile from the southern tip of Guam was the prime candidate – the climate, habitat and resources are essentially identical to the bird’s native home. However, the discovery of a the thriving population of brown tree snakes on Cocos dashed those hopes. Palmyra Atoll, a collection of 26 small islands located more than 1,000 miles south of Hawaii in the Pacific Ocean, then rose to the top of the list.
After a successful rat eradication effort in 2011, Palmyra is predator-free and the lush rainforest is home to a plethora of nesting material and food for endangered birds, including invertebrates and an endemic species of gecko. . Captive sihek eat insects, anoles, and even live mice, but wild sihek eat skinks and geckos in Guam. “It will be really interesting to see what they choose to eat once they are in the wild,” says Stefan Kropidlowski, US Fish and Wildlife (FWS) manager at Palmyra Atoll National Wildlife Refuge.
In July, the recovery team traveled to Palmyra to finalize the details of the introduction. “Immediately, you could see right away where the birds would be positioning themselves on the atoll,” Medina says. “It’s definitely a place where the Sihek can thrive.”
Through a partnership between Nature Conservancy and FWS, Palmyra is also already home to a small research station, increasing the project’s chances of success. “We are such a small, tiny island that most people don’t even know about. The fact that we can help another tiny, tiny island in the Pacific achieve its conservation goals is fantastic,” says Kropidlowski.
While the recovery team’s progress is promising, several regulatory hurdles remain before Sihek calls Palmyra home. FWS is currently accepting public comments on the proposed introduction until September 30, 2022. And prior to publication, surveys will assess possible impacts on native flora and fauna of the introduction of Sihek to Palmyra, which the team does not expect to be a problem. Once finalized, Sihek can be released in 2023.
Then the hard work begins. “The remote location is ideal in some ways, and it can also complicate things,” says Megan Laut, FWS wildlife biologist with the Sihek Recovery Team. The only access to the island is by air or boat, so the birds will experience little human disturbance. But it also means that the supplies needed to build bird enclosures should be sent out well in advance of the birds being released. “If you don’t have the right piece of gear, you can’t rush to the store and get it,” Laut says.
To minimize the transport of germs or foreign insects from birds traveling from multiple facilities to the atoll, 20 kingfisher eggs will travel to Honolulu, Hawaii, where the avians will hand-raise chicks. Nine of these young will eventually travel to Palmyra (the remaining chicks will fly to Guam for captive breeding) where they will live in small cages until they pass health checks. Finally, Sihek can fly freely again.
After release, biologists will monitor kingfishers around the small island – another Palmyra perk – with attached tracking devices like small backpacks. “We can learn a lot by keeping transmitters on birds for a few months,” says Erica Royer, the aviculturist who helped test the methods on captive individuals at the Smithsonian National Zoo and Conservation Biology Institute. “Do they find good food?” And how far do they disperse from the release site? »
Another unknown is when wild birds might start breeding. In continental United States installations, they breed through the winter, but in Guam, they can raise young year-round. Biologists hope these introduced birds – and a second group if Sihek’s first release goes well – will produce wild-born Siheks for the first time since the 1980s. Developing techniques and learning how birds respond to the wild after such a long absence – from foraging to courtship – will aid in the recovery effort and pave the way for future introductions to Guam.
“Ultimately, our goal is to restore the birds to Guam,” Laut says. When will depend on the success of the liberation of Palmyra and the eradication of snakes in Guam. But Medina hopes a return to Guam could take place within five years of the proposed introduction. Sihek could be released on Guam where snake numbers have plummeted, for example, or snake-proof fencing could be used to protect any introduced birds. “There is still hope out there, and there are still actions that can be taken to help save our species,” Medina says. “It will only be the beginning.