NEW ORLEANS (AP) — For the first time since 1939, a whooping crane chick has hatched in the wild in Louisiana.

Whooping cranes are among the world’s most endangered birds. Only about 600 of the graceful 5-foot-tall birds exist, all descended from 15 in Texas.

“I’ve been smiling all day. It’s pretty exciting,” biologist Sara Zimorski of the Louisiana Department of Wildlife and Fisheries said Tuesday.

She said the chick hatched Monday, sometime between a morning check of the nest and another in the evening.

It was reason to celebrate after three disappointments this year: One pair laid infertile eggs, and two others laid eggs that were fertile but never hatched. Biologists collected the eggs and found dead embryos, Zimorski said.

“It’s frustrating, especially since there’s no easy answer” about why the embryos did not survive, she said.

A fifth pair laid eggs a couple of weeks ago. Hatching usually takes about 30 days, so biologists won’t know their fate for about two more weeks.

Biologists may fly over the marsh in the next week or two to see whether a couple of other possible pairs are nesting, Zimorski said.

State and federal wildlife officials have been working since 2011 to create a wild flock of whooping cranes in the general area where Louisiana’s last wild flock once lived.

The one chick to hatch so far may get a sibling within a day or few: Its parents are still incubating a second egg.

Whooping cranes usually lay two eggs, but generally only one chick survives.

“We’re going to be hands-off and observe what happens,” Zimorski said.

There’s also a question about whether cranes need to be brought up by cranes to learn to be crane parents. Birds taught to migrate by following ultralight planes from Wisconsin to Florida have had little success raising chicks. Out of hundreds of eggs, 64 have hatched, but only nine chicks lived long enough to fly, so authorities decided this year that all juveniles added to that flock will be raised by their parents.

But those added to Louisiana’s, at least for the next year or two, will still be raised by people in baggy garments designed to keep the birds from imprinting on humans.