Caribbean parrots, considered endemic, are actually remnants of a millennia-long extinction event

in a new study published in PNAS, researchers have isolated the first ancient DNA from Caribbean parrots that was compared to the genetic sequences of modern birds. Working with fossils and archaeological samples, they showed that two species that were thought to be endemic to certain islands were once more widespread and diverse.

The findings help explain how parrots quickly became the world’s most threatened group of birds, with 28% of all species considered threatened. This is especially true for parrots living on islands.

On his first voyage to the Caribbean in 1492, Christopher Columbus noted that flocks of parrots were so numerous that they “hid the sun.” Today, more than half of the Caribbean’s parrot species are extinct, from large colorful macaws to sparrow-sized baby parrots.

Biologists trying to conserve the remaining parrot species are frustrated by how little is known about their former ranges. This is mainly due to their complicated history with humans.

“People have always been obsessed with parrots,” said lead author Jessica Oswald, a senior biologist at the U.S. Fish and Wildlife Service’s Forensic Science Laboratory. “Indigenous peoples have been moving parrots across continents and between islands for thousands of years. Later, European colonists continued this practice, and we still move them today.”

Centuries of exchange and trade have made it difficult to know how parrots got to where they are today. Half of the 24 species of parrots currently living in the Caribbean were introduced from other regions, and it is not clear whether native parrots evolved on the islands where they live or were similarly transported there.

Fortunately, their popularity with humans means that parrots are occasionally found at archaeological sites. Their bones have been found in piles of trash called midden shells, fish bones, and other remnants of past meals.

“There are records of parrots being kept in homes where they were valued for their feathers and in some cases as a potential food source,” said senior author Michelle LeFebvre, curator of Florida archeology and ethnography at the Florida Museum. Natural history.

Compared to other tropical regions, parrots also have an unusually high fossil record in the Caribbean. However, healthy specimens are rare. More often than not, their bones are broken or isolated, and it is not always possible to determine which species they belonged to.

DNA can provide unequivocal answers in cases where physical comparisons are lacking, and co-author David Steadman was eager to see if they could extract the genetic remains preserved in bone tissue.

Oswald, who worked as a graduate student and postdoctoral fellow at the Florida Museum, recently completed a proof-of-concept in which he successfully sequenced the first DNA from an extinct Caribbean bird preserved in the blue hole for 2,500 years. Using the same methods, he later discovered that an extinct flightless bird from the Caribbean was most closely related to ground-dwelling birds in Africa and New Zealand.

“For me, the most rewarding thing about this project is that we can use the fossils in ways that weren’t even imagined when they came out of the ground,” said Steadman, retired curator of ornithology at the Florida Museum.

The authors pieced together the long history of the parrot family Amazona, focusing on two species, the Cuban (A. leucocephala) and Hispaniolan (A. ventralis) parrots, for which they were able to obtain ancient DNA samples.

Of the two, the Cuban parrots are currently the most common, with isolated populations in Cuba and some of the Bahamas and Turks and Caicos. They are one of the only native parrots in the region that are not in immediate danger of extinction.

The Hispaniolan parrot has had a harder time adapting to human-induced changes. It is listed as endangered by the International Union for Conservation of Nature and is completely endemic to the island of the same name.

Most of the fragmentary fossils collected outside of Hispaniola and Puerto Rico were identified because they belong to the more common Cuban parrots. But when the DNA results came back, they told a different story. Fossils from paleontological sites in the Bahamas were actually from Hispaniolan parrots, indicating that the species’ range previously extended to the Bahamas before humans arrived on the islands.

Similarly, the results show that Cuban parrots once inhabited the largest island of Turks and Caicos, from which they are now absent.

“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 that we didn’t even know existed until we took a closer look at the specimens in the museum.”

The bones, which come from archaeological sites in Turks and Caicos and the island of Montserrat in the far south of the Lesser Antilles, also came from Spanish parrots. They were probably transported there by people and this species no longer occurs on the islands.

Knowing where species once flourished, both naturally by their own means and artificially by humans, is the first step to preserving what’s left of their diversity, Oswald says.

“We have to think about what we consider natural,” he said. “Humans have been changing the natural world for thousands of years, and species that we think are endemic to certain areas may be the result of recent range reductions due to humans. We need a collaboration between paleontologists, archaeologists, evolutionary biologists and museum scientists to really understand the long-term role of humans in changing diversity.”

Brian Smith of the American Museum of Natural History, Julie Allen of Virginia Tech and Robert Guralnick of the Florida Museum of Natural History are co-authors of the study.