A recent study on Caribbean parrots has revealed that species believed to be unique to specific islands were once more prevalent and varied than previously thought.
The research helps to explain why parrots, particularly those on islands, have become the globe’s most endangered bird group.
“Humans did not arrive on most of the world’s islands until relatively recently, making islands favorable places for disentangling the timing and magnitude of natural and anthropogenic impacts on species diversity and distributions,” wrote the study authors.
“Here, we focus on Amazona parrots in the Caribbean, which have close relationships with humans.”
In 1492, during Christopher Columbus’ maiden journey to the Caribbean, parrot flocks were so abundant that they reportedly “obscured the sun.”
But today, over half of the Caribbean parrot species, ranging from macaws to parrotlets, are extinct. The task of conserving the surviving species has been hindered by the limited knowledge of their historical distributions.
“People have always been obsessed with parrots,” said study lead author Jessica Oswald, a senior biologist with the U.S. Fish and Wildlife Service Forensics Lab.
“Indigenous peoples have moved parrots across continents and between islands for thousands of years. Later, European colonists continued that practice, and we’re still moving them around today.”
According to the researchers, centuries of trade have made it difficult to know how parrots wound up where they are now. Half of the 24 parrot species that currently live in the Caribbean were introduced from other areas, and it’s unclear whether native parrots evolved on the islands they inhabit or were similarly transported there.
“There are records of parrots being kept in homes, where they were valued for their feathers and, in some cases, potentially as a source of food,” said study senior author Michelle LeFebvre from the Florida Museum of Natural History.
Parrots are often discovered at archaeological sites, and they have a remarkable fossil record in the Caribbean.
Previously, the fragmented nature of these remains made it impossible to identify the fossil species. But now, recent advancements in DNA technology have made it possible.
David Steadman, a retired curator of ornithology, collaborated with Oswald, who successfully sequenced DNA from a 2,500-year-old extinct Caribbean bird.
“For me, the single most satisfying thing about this project is we can use fossils in ways that weren’t even imaginable when they came out of the ground,” said Steadman.
Using genetic sequencing methods, the experts established connections between extinct flightless Caribbean birds and those in Africa and New Zealand.
The research focused mainly on the Cuban and Hispaniolan parrots of the Amazona genus.
While the Cuban parrot species currently thrives in select areas of the Caribbean, the Hispaniolan species faces potential extinction, restricted to its namesake island.
The DNA analysis led to some surprising revelations. For example, fossils from Bahamian sites previously assumed to belong to the more prevalent Cuban parrots were actually from Hispaniolan parrots.
This suggests that Hispaniolan parrots once ranged through the Bahamas before humans reached the islands.
“One of the striking things about this study is the discovery of what could be considered dark extinctions,” LeFebvre said. “We’re learning about diversity we didn’t even know existed until we took a closer look at museum specimens.”
The study also illuminates the human role in species distribution. According to Oswald, knowing where species once thrived is the first step to conserving what’s left of their diversity.
“We have to think about what we consider to be natural,” she said. “People have been altering the natural world for thousands of years, and species that we think are endemic to certain areas might be the product of recent range loss due to humans.”
“It takes paleontologists, archaeologists, evolutionary biologists and museum scientists all working together to really understand the long-term role of humans on diversity change.”
The study is published in the journal Proceedings of the National Academy of Sciences.
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