How a seabird native to Hawaii has adapted to life in Honolulu’s concrete jungle

HONOLULU– Kaʻiulani Murphy quickly spots white terns flapping their wings when she guides Polynesian canoes across the Pacific.

Birds hunt for food at sea and lay eggs on land. So traditional navigators like her, who look to stars, waves and other elements of nature to cross the ocean, see the bird’s presence as a sign that land is near.

These days, travelers returning to Honolulu have more white terns to track than at any time in modern history. New data shows their numbers have jumped more than 50 percent in the past decade, proof that seabirds are thriving amid the concrete towers, congested roads and hotels of Waikiki, the state’s largest metropolis.

They defy the fate of many other native birds in Hawaii, where diseases and non-native predators on the islands have caused native bird numbers to collapse.

“This is our big city,” said Murphy, who has sailed by canoe to Tahiti, Japan and Rapa Nui. “It’s crazy to me that they reach such a large population in Honolulu.”

There were 691 eggs and chicks in Honolulu trees this week, said Rich Downs, coordinator of the volunteer organization Hui Manu-o-Kū.

The group takes its nickname from the Hawaiian name for the white tern, which means “bird of Kū”, the god of war.

Manu-o-Kū can breed all year round, but their activity peaks from winter to early spring. They are the only seabirds that do not build nests, but lay their eggs on bare tree branches, cliff ledges or windowsills. After hatching, the young sit on a branch until they can fly, their powerful claws helping them to hold on even in strong storms.

They are found near islands in warm waters around the world, but in Hawaii they live primarily among remote, mostly uninhabited atolls in the northwest. The only place they have settled among the larger islands of the archipelago is Oahu, home to 1 million people.

Scientists aren’t sure why these birds thrive in Honolulu. The city could be hospitable because humans have reduced the number of predators like rats and cats around restaurants and buildings. Busy roads can also deter predators. Barn owls and mongooses, other species that like to feed on terns, are rare in the urban core.

“All the lights and noise and the bustle of people and traffic and things like that don’t seem to bother them,” said Eric VanderWerf, executive director of Pacific Rim Conservation, a nonprofit organization that supports native Hawaiian and Pacific birds.

Downtown trees provide favorable habitat. A cut created by the scar tissue of a pruned tree branch is an ideal place for an egg, so well-kept trees create many homes.

The most recent population survey, conducted by Hui Manu-o-Kū in 2023 but not published until now, showed that Oahu’s population of breeding adults jumped 1.5 times to 3,600 compared to 2016.

It provides a striking contrast to Hawaii’s other native birds. Since humans arrived in Hawaii, 71 of the 113 bird species found only on the islands have become extinct. Those that remain are often listed as threatened or endangered. Many are found in small numbers in high altitude forests.

Although native to the islands, manu-o-Kū were not observed breeding on Oahu until 1961, when scientists saw a pair of adults with a single egg.

Decades later, as the bird’s population skyrocketed, Honolulu named manu-o-Kū its official bird in 2007. Schoolchildren sing songs about the species. An annual festival celebrates them every May.

Staff at Hui Manu-o-Kū tie blue plastic ribbons around tree trunks housing eggs and chicks to alert pruners to stay away. The ribbons also help birders track white terns, just like an online map.

For eight years, Joyce Hsieh has been taking photos of the birds as they incubate their eggs, feed the young birds and raise their hatchlings. One of her favorite places is a Target parking lot because she can climb up to the third floor to reach the same level as the birds in the nearby trees.

White terns have about the same body length as pigeons but a larger wingspan. They fly up to about 120 miles (193 kilometers) from land and feast on small fish and squid chased to the ocean surface by larger species like tuna.

Murphy, the traditional traveler, is from Hawaii. She sees parallels between Hawaii’s birds and its people.

Diseases introduced by early Europeans killed Native Hawaiians in large numbers in the 19th century. But the Hawaiians – resilient and adaptive like Manu-o-Kū – are still here and their population is growing.

When she encounters the birds offshore on her way to Oahu, she says it’s like seeing old friends.

“It’s just a special feeling,” she said.