The Carolina parakeet was the only parrot species native to the US; by 1918, we had killed them all. New evidence explains their demise.
Ah, the olden days, when colorful parrots flocked from southern New England to the Gulf of Mexico and as far west as Colorado. While some places in the country are graced with the raucous squawks of non-native parrots, the Carolina parakeet (Conuropsis carolinensis) was the only parrot species native to the United States. I am floored by cardinals and blue jays, to have seen flocks of 200 to 300 of these birds, with their vibrant green color and wingspans of nearly two feet – what a wonder it must have been.
But no, we don't get to see these bodacious birds anymore – the last known wild specimen was killed in Florida in 1904, and the last captive bird, named Incas, died at the Cincinnati Zoo on February 21, 1918. He died within a year of his mate, Lady Jane.The reason behind why the parakeet went extinct has never been distinctly clear. That they were hunted extensively for their feathers – because what good was a 19th-century hat without bird parts? – obviously added to their demise, but experts have suggested habitat destruction and poultry pathogens as other culprits.
But now, new research has made one thing more clear: The Carolina parakeet extinction was driven by human causes, as revealed by DNA sequencing.
Researchers from the Institute of Evolutionary Biology (IBE, a joint institute of the Pompeu Fabra University (UPF) and the Spanish National Research Council (CSIC)) in Barcelona and the Globe Institute at the University of Copenhagen explored the genome for signs found in endangered species but did not find them, thus concluding that "Carolina parakeet extinction was an abrupt process and thus solely attributable to human causes."
The researchers were able to sample the tibia bone and the toe pads of a specimen that was collected by Catalan naturalist Marià Masferrer (1856-1923). They also sequenced the genome of a close living relative, the sun parakeet from South America.
Among other things, they looked for signs of inbreeding and population decline, both clues that can be found in endangered species – but they did not find them, "which suggests that its rapid extinction was mainly a human-mediated process," notes UPF.
The authors write in the study, "scarce evidence of inbreeding indicates that it suffered a very quick extinction process that left no traces in the genomes of the last specimens. In fact, the bird’s final extinction was likely accelerated by collectors and trappers when it became evident that it was extremely rare."
"Other potential factors for Conuropsis extinction, such as the exposure to poultry pathogens, will likely require a metagenomic screening of at least several parakeet specimens," the authors continue, "however, preliminary results from our sample do not show a significant presence of bird viruses."
The methodology developed to reconstruct the extinction history from the bird genome could be used in the future to foresee other possible human-related extinctions, and to further protect the endangered species by applying conservation plans in time. "We can use genomics to test the dynamics of other extinction processes and infer if they are entirely caused by humans, because long-term demographic declines leave specific signals in the genomes of the species," says lead author, Carles Lalueza-Fox.
It may be tragically too late for the Carolina parakeet, but at least we now have better tools for predicting other extinctions – may the cardinals and blue jays endure.
The research was published in Current Biology.