Science

Launched in 1998, the event has exploded in size as birding has become increasingly popular across the globe and apps make identification and data submission more accessible. Last year, more than 830,000 people participated in the event, digitally capturing around 70 percent of the world’s avian species everywhere from Australia to Canada. This year, the event, which took place from Feb. 14 to 17, had record-breaking levels of participation.

The global datasets generated during the Great Backyard Bird Count and other similar events throughout the year help scientists track how bird populations are changing across time and space, capturing what Cornell Lab’s Mya Thompson calls one of “the heartbeats of the planet.”

But they also show the ways this heartbeat is faltering in the face of climate change and habitat loss. Experts are rushing to figure out how to slow bird losses before they flatline.