Changing happiness for two Bahamian endemics

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Changing happiness for two Bahamian endemics

In recent months, the outlook for the protection of two bird species endemic to the Bahamas has changed dramatically, one – the Bahama Oriole – thanks to improved knowledge and the other – the Bahama Warbler – due to catastrophic natural events.

For several years, researchers from the University of Maryland, Baltimore County (UMBC), in collaboration with the Bahamas National Trust (BNT), have been studying the critically endangered Bahamian oriole, which can only be found on Andros Island. For years, these showy yellow-and-black songbirds were believed to be confined to the east coast of Andros, where they preferred to nest in coconut trees in and around human settlements.

With fewer than 300 individuals, the species appeared to be threatened by the loss of palm nesting sites due to a deadly palm yellowing disease combined with breeding parasitism from Shiny Cowbirds. Such a tiny population would rank the species among the most endangered in the western hemisphere.

However, studies conducted from 2016 to 2018, some of which were supported by the American Bird Conservancy, changed that narrative, beginning with UMBC alumnus Daniel Stonko’s documentation of the first Bahamian oriole nests in the pine forest. This work was followed by that of another UMBC alumna, Briana Yancy, who showed that nesting in the pine habitat was not uncommon for Bahama Orioles; In fact, the birds often prefer it.

Bahama Warbler, Copyright Dubi Shapiro, from the Surfbirds Galleries

At 2,300 square miles, Andros is by far the largest of the 700 main islands in the Bahamas. With more than 20 percent of the island covered in pine forests, the status of the Bahama Oriole urgently needed to be reassessed. That brings us to the present and the publication of a new study by UMBC alumnus Michael Rowley and the co-authors of UMBC, BNT, the University of Florida, and the Smithsonian Conservation Biology Institute. Rowley and the team conducted surveys of around 25 percent of Andros and concluded that the oriole population is likely to be between 1,300 and 2,800 birds – perhaps ten times the previous estimate. Rowley says the new information is “an advance in conservation” and notes, “It makes the world a little more informed about what to focus on.”

Kevin Omland, mentor and head of research at UMBC, will be working with BirdLife International, the International Union for Conservation of Birds (IUCN) Red List for birds, to review the oriole’s population status. The species is likely to be graded from Critically Endangered to a lower threat category. Dr. Omland and his students now turn to learning where the orioles go after nesting. In order to best direct conservation efforts, this information is key to understanding how important other habitats could be to the species in other parts of its annual cycle.

Elsewhere in the Bahamas, Hurricane Dorian, a Category 5 storm, hit northern Abaco and Grand Bahama in the first days of September 2019. The human toll on both islands has been tragic and these communities are still struggling to recover. In January and February 2020, expeditions led by BNT and ABC with the support of the National Geographic Society and BirdsCaribbean examined the status of resident and migratory birds on the two islands and quantified the damage to their forests.

While northern Abaco was devastated, extensive pine forests in southern Abaco, including Abaco National Park, were spared and contained robust populations of pine dependent birds, particularly the endemic Bahamian warbler known only from Abaco and Grand Bahama. In contrast, the pine forests on Grand Bahama have been almost completely destroyed. Only one endemic bird species was discovered during the investigation, a lone Bahamian yellowthroat and, critically, no Bahamian warbler. The Bahamian nuthatch, known only from Grand Bahama and last seen in 2018, is feared to be extinct after Dorian.

After the post-Dorian expeditions, the BNT-ABC team, along with William Hayes from Loma Linda University in California, shared their new information on the Bahama Warbler with BirdLife International. The team recommended moving the Bahamian Warbler from Near Endangered to Endangered as it is now actually a single endemic island with at least 95 percent of its population confined to Abaco, which may have fewer than 1,700 birds. BirdLife agreed, and BNT is intensifying efforts to better understand the habitat and food needs of the warbler on Abaco and the long-term prospects for habitat restoration on Grand Bahama.

The history of these two Bahamian endemic species highlights conservation issues specific to the Bahamas, but also others shared with other West Indies. The Bahama Oriole and the Bahama Warbler, as well as the now possibly extinct nuthatch, are examples of the spectacular diversity of highly localized bird species that have developed in isolation on Caribbean islands, with many being restricted to individual islands.

These restricted-range island species are inherently more prone to extinction with literally all eggs in one basket – threats like hurricanes or invasive, alien species can quickly affect their entire range. In the Bahamas, the islands of Andros, Abaco, and Grand Bahama hold the lion’s share of the archipelago’s pine forest and also support other pine-dependent species, including the endangered Bahamian swallow and the Bahamian subspecies of the Cuban parrot.

Effective protection and management of the Bahamian pine forests are critical to maintaining strong populations of these species. In the north of Abaco and Grand Bahama, forest restoration will be key to restoring the Bahamian warbler populations and thereby improving the long-term safety of this species. Our changing climates and the increasing number and severity of hurricanes make these efforts urgent.