Manu-o-Ku, or fairy terns, seem to be thriving in Honolulu. How classic that this month Mayor Mufi Hannemann designated this awesome native Hawaiian seabird as the official bird of Honolulu.

They are threatened, but the slender white birds seem to be having chicks, catching small fish out at sea, and soaring gracefully high overhead against the blue or grey skies.

As the mayor said, he chose fairy terns because we cherish them, and many people and organizations have been asking Hannemann to designate this special native bird of land and sea as our mascot.

In a ceremony on the Honolulu Hale lawn on April 2, the mayor was joined by representatives of the Polynesian Voyaging Society, the Fish and Wildlife Service and the Audubon Society in the proclamation ceremony.

The manu-o-Ku breeds throughout the Northwestern Hawaiian Islands. Among the eight major islands of Hawai'i, it breeds only on O'ahu.

"Manu-o-Ku is a natural choice for us, because its home is the entire City and County of Honolulu, which encompasses O'ahu as well as the Northwestern Hawaiian Islands," Hannemann said. "In addition, this handsome bird has been a traditional wayfinder and guide for Polynesian voyagers of ancient times as well as today."

The manu-o-Ku will be featured in the 21st Century Ahupua'a campaign Hannemann is launching to ensure a sustainable future for Honolulu.

"It's a natural fit. Manu-o-Ku is a creature of the sea and land," the mayor said. "As a threatened species, it embodies the fragile nature of Hawai'i's unique environment. And we are pledged to protect and nurture both the 'aina and manu-o-Ku for future generations."

Fairy terns mate for life, and both parents nurture and feed offspring. They catch tiny fish at sea, sometimes up to four per beakful.

How do they do that? I've missed waves while surfing from watching them and wondering how they catch a second fish and don't drop the third.

They lay their single egg on a bare branch — no nest. Somehow the parents take turns on the egg without dropping it.

Manu-o-Ku originally laid their single eggs on the ground, where they were wiped out by alien predators such as rats, mongooses and feral cats. The akamai ones evolved to lay their single precious egg on a safe, high crotch of a big tree.

Now they like BIG trees. Big trees with broad branches make a good spot for the egg and chick.

Good arborists, tree trimmers and land managers know to watch out for the brooding birds and leave them alone — no trimming during April, when it's peak nesting season. (Excess pruning, in general, does nobody any good, and it's expensive, too.)

When the chick hatches, it is a white bundle of fluff with bright black eyes and a sharp beak.

Manu-o-ku have the webbed feet of a seabird, with claws on the tips that can cling to the high tree branches.

Even in the strongest winds, they don't seem to blow out of the tree. If you see two birds flying high overhead, that is a mated pair. A group of three means parents are teaching their chick to fly and catch fish.

Ino John Lee, aka Dr. Tree, is our lead tree trimmer at the Hale Koa Hotel. We were talking about trees that needed trimming after the recent wild winds and about which might have nesting manu-o-Ku.

He said that in Samoa, where he grew up, fishermen love manu-o-Ku. "When they see them diving out at sea, we know there are mahimahi or 'ono there."

The Fish and Wildlife Service quietly monitors the Hale Koa Hotel's care for this rare bird. Last year we successfully fledged six chicks.

There is also one nesting in the giant brassaia tree outside City Hall.

Laura Thompson, the mother of Nainoa Thompson, was one of the key people to convince the mayor to pay tribute to this native bird of our urban forests.

A few years ago, Keith Swindle of the FWS moved here from Portland, Ore., which has an epic city bird, the great blue heron. Swindle learned about and started looking after the manu-o-Ku, and he and fellow biologist Eric VanderWerf came up with the idea of honoring, and thus protecting, our manu-o-Ku.

Heidi Bornhorst is a sustainable-landscape consultant. Submit questions to islandlife@honoluluadvertiser.com or to Island Life, The Advertiser, P.O. Box 3110, Honolulu, HI 96802. Letters may be published or distributed in print, electronic or other forms.