After the 2019 hurricane, the Bahama Warbler is likely confined to a single island

The endangered Bahamian warbler may be surviving on a single island after the devastation caused by Hurricane Dorian in 2019, researchers at the University of East Anglia say.

A new study shows the bird’s distribution and ecology on Grand Bahama Island before the hurricane hit. The research team says the warbler could now only survive on nearby Abaco Island, after Hurricane Dorian destroyed its forest habitat on Grand Bahama.

The research comes from the same team that discovered what is thought to be the last living Bahamian nuthatch, a species that may have become extinct due to Dorian. David Pereira and Matthew Gardner, master’s students at UEA, conducted the fieldwork for three months as they searched for the warbler and nuthatch on Grand Bahama.

“Although more than half of the birds endemic to the Bahamas are considered globally endangered,” says UEA professor and study leader Diana Bell, “there has been little international commitment to help remedy the situation”.

The nuthatch, which was declared a separate species from the mainland brown-headed nuthatch in 2021, has not been reported on eBird since July 4, 2018. In the spring of 2018, research teams from UEA and the University of the Bahamas-North discovered the nuthatch at three separate locations on Grand Bahama. No more than two individuals were spotted at a time. Dorian reached the Bahamas 15 months later, and the species is now threatened with extinction.

The Bahamas Warbler is now endangered

The Bahamas Warbler is a small gray and yellow bird with a long beak that was previously considered a subspecies of the Yellow-throated Warbler. Prior to Dorian, it was found only on the islands of Grand Bahama and Abaco.

As of 2020, the only sightings posted on eBird are from Abaco and a nearby 1,000-acre island called Castaway Cay (an exclusive port for Disney Cruise Line ships).

The warbler is now classified as an endangered species, largely because its pine forest habitat has been severely affected by urban development, human-caused fires, illegal dumping of waste (that’s i.e. fly dumps), logging and increased hurricane strength and frequency. .

The team wanted to assess the bird’s conservation status and determine its habitat needs after a Category 4 hurricane (Matthew) hit the island in 2016. They also wanted to learn more about its habitat preferences for conservation purposes.

In the spring of 2018, Pereira and Gardner searched for the warbler in 464 Grand Bahama pine forests. They played recorded warbler songs to attract birds and studied the habitat at each location, paying particular attention to habitat damaged by hurricanes and fires.

They found a total of 327 warblers present in 209 of the 464 points surveyed. No less than 71 percent of the sightings took place in the forests of the center of the island and 29 percent in the east.

“We found that warblers were more likely to be present in sites with fewer mature trees without needles and some burnt vegetation,” says Pereira. “They seem to prefer living among taller, more mature thatch palms. This is likely because these trees are able to survive wildfires and also harbor insects that warblers feed on.

Pereira and Gardner also found that “the species is quite adaptable, especially when it comes to fire-affected areas. This is likely because they can feed on tree trunks and use their beaks to crawl under burnt, peeling bark.

Attention mainly turns to Abaco

Their co-supervisor, Professor Nigel Collar of BirdLife International, said: “We assume that Hurricane Matthew, which hit Grand Bahama only 18 months before the start of our 2018 survey, killed a significant proportion of the warblers in the Bahamas on the island. And it’s possible that our findings about the bird’s preferences largely reflect the habitat that provided it with the best shelter. »

Fifteen months after fieldwork was completed, Hurricane Dorian devastated Grand Bahama with winds of 295 km/h for more than 24 hours, creating such human misery and economic damage that three years later the situation of the island’s fauna remains unclear.

“It’s possible that the entire warbler population in the Bahamas was wiped out,” says Gardner. “But we do know that the only other population of the species, in Abaco, survived in the south of the island, where much of the forest remained standing.”

“We hope our ecological knowledge will help with conservation management at Abaco, but both islands now need to be studied,” Bell added.

Thanks to the University of East Anglia for this news.

The article led by Pereira and Gardner is available from the journal Bird Conservation International.