There and Back Again: A Parrot
Great adventure stories often contain a prescribed set of parameters: an unlikely hero, a journey fraught with trial and tribulation, and, of course, a villain. And who says these chronicles have to revolve around people? For South American burrowing parrots, evolution of the species reads like an adventure tale. New research reveals how these little guys managed to colonize new habitats in the face of seemingly insurmountable obstacles.
Small, bright green, and fussy when it comes to habitat, the burrowing parrot comes across as quite the homebody. The birds make their nests by digging into soft rock cliffs found in dry stretches of Argentina and Chile, choosing sites close to water sources since they must drink at least three times daily. Four subspecies of burrowing parrots occupy a habitat range thousands of square miles wide. Though the same species, parrot populations from Chile and Argentina are distinct in size and coloration.
Smack-dab in the middle of the Chilean and Argentinean populations’ ranges sit the colossal barrier of the Andes Mountains. The mountains reach heights of over 20,000 feet, clearly a formidable and dangerous roadblock for any bird thinking of making a journey to the other side.
An international team of ornithologists had faith in the parrots’ tenacity, though, and decided to investigate the birds’ evolutionary origins. The scientists suspected that the burrowing parrots hailed from one side of the mountain or the other, but that such a journey was probably a single occurrence, or at least happened very rarely. To test this hypothesis, the team collected the molted feathers of 66 different burrowing parrot colonies distributed over thousands of miles. They extracted mitochondrial DNA—a common trick biologists use for determining the evolutionary relationships amongst species—to reveal the ancient storyline of the parrots’ journey through time and space.
The fascinating results, published in Frontiers in Zoology, show that the distant relatives of today’s burrowing parrots hailed from the Chilean side of the mountains. Apparently, the birds managed to cross the Andes only once, back in the Upper/Late Pleistocene (about 120,000 years ago), at a time when the mountains were covered with massive glaciers. The researchers suspect that the birds traversed a mountain pass, probably about 10,000 feet high, to accomplish this feat. Thanks to their efforts, burrowing parrots fill Argentina’s gorges and ravines today.
Though our feathered heroes made it across the treacherous mountains, the birds’ plight is far from resolved. Only about 5,500 individuals of the threatened Chilean subspecies linger on in their western range. In Argentina, the situation is different, with burrowing parrots often wrongly labeled as agricultural pests. Several colonies have been destroyed thanks to this misconception, including the largest known group of about 50,000 nests. In both countries, habitat destruction and collection of birds for the pet trade also paint a tenuous picture of the species’ future, and climate change casts its own abstruse shadow. Whether or not humans ultimately reveal themselves as the burrowing parrot's villain or savior is yet to be told.