Emily Sohn writes:

The North American Breeding Bird Survey, organized by the US Geological Survey and Environment Canada, has enlisted thousands of participants to observe birds along roadsides each June since 1966. Audubon’s Christmas Bird Count, which began in 1900, encourages people to join a one-day bird tally scheduled in a three-week window during the holiday season. There are shorebird censuses and waterfowl surveys, all powered by citizen scientists.

This wealth of longitudinal recordings started to turn up signs of distress as far back as 1989, [Peter] Marra says, when researchers analyzed data from the North American Breeding Bird Survey and concluded that declines were occurring among most of the species that breed in forests of the eastern United States and Canada, then migrate to the tropics.

Thirty years later, Marra and colleagues reassessed the situation using multiple bird-monitoring datasets from North America along with data on nocturnal bird migrations from weather radars. They found stunning losses. Since 1970, the team reported in Science in 2019, the number of birds in North America has declined by nearly 3 billion: a 29 percent loss of abundance. The paper used several methods for estimating changes in population sizes, Marra says, and “they all told us the same thing, which was that we’re watching the process of extinction happen.” [Continue reading…]