A genetic study, published by the journal Current Biology, has revealed that the extinction of the only native parrot in the US appears to be solely caused by humans.
The study, which involved genome sequencing of a stuffed Carolina parakeet held in a private collection, discovered that the extinction of the native parrot was likely caused entirely by humans.
Unlike other animals that have been in decline for many years, the Carolina parakeet's DNA displayed no signs of inbreeding but its genetic sequence suggests populations were higher until the expansion of European settlers.
The Carolina parakeet is characterized by its green feathers and a yellow head. It measured around 13 inches long and inhabited old-growth forests along rivers and in swamps.
These parrots went extinct abruptly, with the last captive specimen dying in Cincinnati Zoo on February 21, 1918. Prior to its disappearance, the parrot can be found in New England in the east to Colorado in the west.
Study co-author Carles Lalueza-Fox from the University of Barcelona said: "Many endangered species have been sequenced and what seems to be a pattern is that when populations are small and declining for a long period of time, this leaves some signals in their genomes that can be recognized."
"Even if you have a single specimen, as here, we have a genome from the father and a genome from the mother; two copies of each chromosome. If the population has been small for thousands of years, these two copies will be very similar to each other and over long stretches sometimes they will be identical," Dr. Lalueza-Fox added.
Dr. Lalueza-Fox explained: "The inference is that this bird was not subjected to a very long demographic decline for thousands of years, it was something very quick." The researchers said deforestation, along with hunting and trapping, must have caused the extinction, along with disease and competition with non-native honeybees.
They are looking at the Carolina parakeet as one target of de-extinction through genome editing of its closest relative, the Sun parakeet found in South America.
