The population of Florida's most critically endangered bird just got a little larger.
Four grasshopper sparrow chicks were hatched in a Loxahatchee laboratory this week, marking the first success of a captive breeding program launched out of fear the tiny birds were about to go extinct.
The hatchlings, however, won't be released into the wild, according to U.S. Fish and Wildlife Service spokesman Ken Warren.
"Those initial four are going to be kept in captivity," he said. "There's no current plan to release them into the wild. Instead, they'll be held and used to build up the captive colony."
In a few years, after there are a sufficient number in captivity, federal and state officials will consider using the lab-hatched birds to supplement the dwindling numbers still inhabiting the grassy prairies of Osceola and Okeechobee counties, he said.
Currently, biologists estimate no more than 150 are left, and heavy rains last week wiped out many of the wild birds' first attempts at nesting. They are regarded as among the most endangered birds in North America.
"This captive breeding program might buy us time to unravel the compounding factors causing the sparrows to decline so rapidly," said Larry Williams, who is in charge of the federal agency's South Florida office. The agency has spent $120,000 a year for the past four years on this.
When the captive breeding program was launched in 2013, experts were predicting the grasshopper sparrow would go extinct in three to five years, just like its cousin, the dusky seaside sparrow. The dusky disappeared from the Earth in 1987 when the last survivor died at Disney World.
If the Florida grasshopper sparrow vanishes, it would be the first bird species to go extinct in the United States since then.
Florida grasshopper sparrows are about 5 inches long, with flat heads, short tails and black and gray feathers that help them hide their nests amid the low shrubs and saw palmetto of the state's grassy prairies.
They are generally heard more than seen, with a call that consists of two or three weak notes followed by an insectlike buzz — hence their name.
The bird was first described in 1902 by U.S. Army surgeon Maj. Edgar A. Mearns, when their population was widespread across south-central Florida. By the 1970s, so many of the prairies that form their habitat had been ditched and drained and converted to pastures or sod production that the sparrow population plummeted. They were added to the federal endangered species list in 1986.
Biologists captured seven juvenile birds in 2015 and took them to the Rare Species Conservatory Foundation in Loxahatchee. They were reared to be independent of humans and began pairing up for breeding in April.
A mother bird began hatching a clutch of four eggs on Monday. As of Wednesday, biologists said, the female appeared to be properly caring for and feeding the four nestlings. The chicks should be ready to leave the nest and start trying to fly about nine days after they hatched. In three weeks, they should be completely independent.
"This breakthrough is great news," federal biologist Sandra Sneckenberger said. "Because the Florida grasshopper sparrow couldn't be more vulnerable."
Contact Craig Pittman at [email protected] Follow @craigtimes.