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A brown and white hawk perched on a tree branch
Information icon A Puerto Rican sharp-shinned hawk. Photo © The Peregrine Fund.

Puerto Rico’s sharp-shinned hawk soars again thanks to Service partnership

The future for Puerto Rico’s sharp-shinned hawk — or gavilán de sierra — looked bleak in 2017, with only 75 of the federally endangered raptors soaring above the island’s deeply forested hilltops.

And then Hurricane Maria hit.

Russell Thorstrom, a biologist with The Peregrine Fund, visited a few months after the winds topped 155 miles per hour and more than two feet of rain fell. He estimated only 19 sharpies survived.

“The forest destruction was incredible,” said Thorstrom, the nonprofit’s project director for the West Indies and Madagascar. “It wiped out a lot of habitat and nesting sites. I can’t imagine how the birds, hunkering down on the forest floor, avoided all the debris flying around.”

The Fund, partnering with the U.S. Fish and Wildlife Service, undertook a Herculean recovery effort to save the hawks. Biologists collected eggs from the few remaining nests, fledged them and returned most back to the wild. The first female released in 2018 was observed this year with a previously known breeding male.

Three tiny, fluffy white birds in a nest
Puerto Rican sharp-shinned hawk nestlings. Photo © The Peregrine Fund.

“The accomplishments have been nothing short of amazing,” said Leo Miranda, the Service’s director for the South Atlantic, Gulf and Mississippi Basin region which includes the Caribbean.

“Puerto Rico — my home and my heart — needs wildlife success stories like this. A hawk soaring over the Cordillera Central is a symbol of rejuvenation and resilience for us all.”

Less than two dozen survived hurricanes

In the 1980s, scientists tallied maybe 250 of the sharp-shinned hawks endemic to Puerto Rico. The short-winged, long-tailed accipiter stands a foot tall with a slate-gray back and a reddish-orange striped chest. It’s built to adroitly maneuver the thickly forested hillsides in search of prey — bananaquits, bullfinches and tanagers. When nesting, between March and July, the hawks prefer the tall, hard-to-reach treetops of El Yunque National Forest or the state forests of Maricao, Toro Negro, Guilarte and Carite.

At least they used to.

Hunting, egg-eating predators and ever-encroaching mankind posed significant threats to the birds. So too did bot flies that burrow into nestlings’ skin, sapping their energy and lives. The hawks were placed on the endangered species list in 1994 with about 150 known to be alive.

The Peregrine Fund, known for its work in the recovery of peregrine falcons, California condors and Mauritius kestrels, began monitoring sharp-shinned nests in 2015. Two years later, Thorstrom and colleagues counted 75 birds — 16 breeding pairs — at four locations on the island.

And then Maria hit — two weeks after Hurricane Irma. Maria’s winds destroyed homes, powerlines and cell towers. The rains caused widespread flooding and landslides that washed out roads and reconfigured mountains. It took more than a year for electricity to be restored island-wide. Nearly 3,000 people died.

The forests, and hawk habitats, were hammered. An estimated 30 million trees were toppled or damaged. Less than two dozen sharpies survived, but it was hard to know precisely given the hurricane’s devastation and the inability to count birds. A half-hour trek through the woods to monitor a bird’s nest now took 2 ½ hours, Thorstrom said. Eventually, the hawks were found only in Maricao, Guilarte and Toro Negro forests. Something had to be done to keep the birds from sliding into extinction.

A challenge, then a success

The Service put up $100,000 for a sharp-shinned captive breeding program. The Peregrine Fund raised another $110,000. And then Thorstrom and a small group of biologists went egg-hunting.

“The most challenging thing was finding those birds,” he said. “The only time you get a chance to see these birds is during their courtship display when they get above the forest and do a little dance. Once the breeding season starts the birds stay in the forest and you don’t see them at all.”

The biologists collected eggs from three nests, incubated and fledged them and returned six of the 20-day old birds to an artificial nest in the mountains. The scientists supplemented the wild birds’ food stocks with shiny cowbirds and Coturnix quail. They also treated nests for the parasitic flies.

Earlier this year, the coronavirus shut down operations. But not before short-term success was guaranteed.

“One of the wild-banded nestlings, and the first female-banded bird we released, moved together from Guilarte to Maricao,” Thurstrom said by phone from Idaho, where he lives. “That’s never been documented before. Seeing birds that you’ve actually released surviving and making it is really a great accomplishment.”

Today, maybe 30 sharp-shinned hawks fly the cloud forest skies. Their resurrection is testament to hard work by a variety of Commonwealth, federal and nonprofit conservation groups, as well as a determination to not let Puerto Rico’s threatened and endangered species disappear. Earlier this year, for example, Service biologists released 30 Puerto Rican parrots into El Yunque — the first birds to fly free in the forest since hurricanes Irma and Maria. And last month, the Service designated more than 27,000 acres as “critical habitat” for the elfin-woods warbler — or reinita de bosque enano – which lives in the El Yunque and Maricao preserves.

“This is indeed some much-needed good news after all that Puerto Rico has been through these last few years,” Miranda said. “And, let me be clear, we will not let Puerto Rico’s natural heritage disappear.”


Dan Chapman, public affairs specialist, (404) 679-4028

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