As Climate Warms, a Return Expedition to a Peruvian Mountain Reveals Bird Species on an Escalator To Extinction

In 1985, a team of researchers from Chicago’s Field Museum including John Fitzpatrick (who later served as director of the Cornell Lab of Ornithology from 1995–2021) led an expedition to a remote mountain ridge in northern Peru. They documented the rich tapestry of birdlife along a path that rose more than 3,000 feet from a river to the top of the ridge.

More than 30 years later, Fitzpatrick returned there to retrace his steps with others including Ben Freeman, a recent Cornell PhD now at the University of British Columbia. This time, they found that species already living on the ridgetop now have smaller ranges. At least eight species have disappeared altogether.

As the climate warms, birds are moving upslope to cooler temperatures. As they run out of mountaintop, the next step is extinction. The researchers suspect this is just one example of a pattern emerging on mountain slopes all over the world.

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