Back in 2014, biologist Sahas Barve was studying songbirds in the Himalayan mountains in Asia. The temperature was a bitter -10°C (14°F), and despite wearing multiple jackets, Barve still felt cold. Meanwhile, a tiny bird called a goldcrest flying above him seemed unbothered. How had the bird adapted to survive in such frigid temperatures? Barve decided to find out.
Barve, now the director of avian ecology at the Archbold Biological Station in Florida, studied the feather composition of more than 200 Himalayan songbirds. He found that species living at higher altitudes have feathers that are more downy than those living at lower altitudes. The extra-soft feathers help trap heat and keep the birds warm.