Male sihek of a feather flock together — at least, that’s what’s happening at the Oregon Zoo. It’s a discovery upending previous beliefs about a territorial and critically endangered bird species.
Sihek (pronounced “SEE-hek”), also known as Guam kingfishers, are brightly colored, long-billed birds endemic to Guam. Zoo scientists have long believed that males couldn’t be housed together without risk of infighting.
But the Oregon Zoo has kept its three males in the same aviary for about two years without incident. It’s a promising finding for zoologists across the U.S. and Guam who are trying to revive the species with limited space.
One of three male sihek, or Guam kingfishers, that are cohabitating at the Oregon Zoo in Portland, Ore. Conservationists have long believed males couldn't share the same aviary, but zoos needed to make space as the critically endangered birds increase their numbers.
Michael Durham, Courtesy of the Oregon Zoo
Sihek were declared extinct in 1988 after invasive snakes in Guam killed most of the birds. Brown tree snakes — native to the Australian coast and its northern archipelagos — took over the island during World War II, likely arriving by cargo ships. They have decimated most of Guam’s native bird species.
Though officially extinct, a couple of dozen sihek survived. Zoo biologists brought them into captivity in the 1980s. Their numbers have since grown to 125 adults, including 81 males and 44 females.
Zoos initially kept the males separate, out of an abundance of caution, but they eventually needed to make space.
In 2024, the Oregon Zoo opted to try housing three males together to see if they could get along.
“It just got to the point where someone needed to try something different, and Oregon agreed to try that,” said Nicole LeGreco, a bird and reptile curator at the Oregon Zoo. “They’re hopeful that we can get a couple other zoos to start doing this, take some of those surplus males and free up space.”
Zoos have raised enough sihek to reintroduce them to the wild. Biologists released nine young sihek on the island of Palmyra Atoll, more than 3,000 miles away from their native habitat, as wildlife officials try to eradicate brown tree snakes from Guam. Those birds laid eggs last year.
The sihek at the Oregon Zoo aren’t destined for Palmyra Atol. They’re likely to remain in Oregon. And the zoo doesn’t plan to add more sihek to its aviary.
Visitors can see the colorful bird species in person at the zoo’s walk-in Vollum Aviary, though it might be a challenge.
“They’re pretty quiet,” LeGreco said. “They hide in our space, and they can be really difficult to find. They blend in really well in the canopy in there.”
