Los Angeles: North America’s tallest bird, with a population of about 600, has lost three adults to gunfire in recent months, which “senselessly” undercuts plans to breed a thriving population of the radiant white whooping crane, wildlife authorities say.

Decades of research and millions of dollars have been spent by government and private organisations to revive the species, whose population shrank to 23 in 1954, according to the US Fish and Wildlife Service.

The deaths of the whooping cranes in Kentucky and Louisiana bring the number of intentional killings of the endangered birds to at least 19 since 2001. That exceeds the average number of cranes — 13 — released into the wild each year by conservationists, according to Operation Migration.

“It’s a huge loss in terms of finances, safeguarding the species, breeding potential and emotion for the teams who have been working with the birds,” Joe Duff, the organisation’s co-founder and chief executive, said on Saturday.

On Friday, two cranes were found shot in southwestern Louisiana, state officials said. The 3-year-old female crane died. A 4-year-old male, who according to X-rays suffered two bone fractures on a wing, was scheduled to have surgery Sunday morning at Louisiana State University.

“There is a high risk of infection because the fractures are open, but the bird recovered well from anesthesia after the radiographs today,” Ginger Suttner, spokeswoman for the school of veterinary medicine, said late Saturday.

The two were the oldest pair among 33 whooping cranes in Louisiana. The birds, which had been tagged and were monitored by Louisiana officials, were expected to produce a chick in a few years.

“It’s a devastating setback and such a senseless act,” said Robert Love, Department of Wildlife and Fisheries administrator. “Don’t shoot big white birds. It’s that simple.”

The 5-foot-tall birds, which typically live for at least two decades, neared extinction in the early 20th century. Today’s 600 whooping cranes are spread among three main flocks in North America.

In 2011, Louisiana joined programmes to revive its native whooping crane population, once the nation’s largest. Officials said they would offer a $1,000 (Dh3670) reward for information leading to an arrest in Friday’s shootings.

Three other Louisiana cranes have been killed in the last two years. Two minors were arrested in one case, but whether they were prosecuted is unclear because the juvenile records are sealed.

In January, federal wildlife officials in Kentucky announced a $7,200 reward — later increased to $15,520 — for information about a whooping crane pair believed to be shot together in November. One was about 6 years old, the other 4.

The GPS-tracked lifelong mates were found five miles apart, and one was recovered alive. It was euthanised after rehabilitation efforts failed.

Hunters may have confused them for sandhill cranes, which can be legally killed in Kentucky during certain months.

Wing span

Radiant white, except for black wingtips and a red scalp, whooping cranes were named for the sound of their danger call. Their wings would span from former basketball player Yao Ming’s head to his toe.

The birds, also known for their dance-like movements, are protected under the Endangered Species Act and the Migratory Bird Treaty Act. Shooting a whooping crane could lead to a $100,000 fine and a year in federal prison.

A year ago, a 26-year-old South Dakota man pleaded guilty to killing a whooping crane and was sentenced to two years’ probation and an $85,000 fine, according to the US attorney’s office.

But experts have said bringing federal charges isn’t easy.

In one case, a juvenile who admitted shooting a whooping crane was charged in Indiana state court with a misdemeanour and eventually fined $1, a punishment that rankled animal rights groups.

Duff, Operation Migration’s founder, said breeding the birds and teaching them to migrate costs $100,000 apiece on average. The instructors wear white suits so the cranes don’t become comfortable around humans. And a small plane leads the birds through the correct flight path. His group relies on private donations.

“These shooters — they are not real hunters, but they are vandals with a gun who just want to destroy something or take their anger out,” he said. “It’s unbelievably selfish.”

Whooping cranes face huge challenges because they are big targets, similar to the critically endangered California condor, whose 10-foot wingspan makes it the largest North American bird. Whooping cranes don’t reach sexual maturity until they are 4 or 5 years old. They usually have only one chick at a time, and just one in four survives the first year.

“The protection of adults is critical,” said Love, the Wildlife and Fisheries administrator. “This species is just so vulnerable to human harm.”

More than half of whooping cranes live in the wild. Most migrate 2,500 miles each winter from their breeding grounds in northern Canada to Aransas National Wildlife Refuge along the Texas coast. A festival is scheduled there for February 20 to celebrate the cranes’ arrival.

A few birds die each year during the journey, killed by predators or by crashing into power lines. But the steady number of unnatural deaths angers environmental advocates.

Richard Beilfuss, chief executive of the International Crane Foundation, said on Facebook last month after hearing of the Kentucky shooting: “In this imperiled species, every crane counts towards recovery. ICF is deeply troubled by the deaths.”