A recent study published in the journal Science reported that nearly 3 billion fewer birds exist today in North America than in 1970.
“Three billion is a punch in the gut,” says Peter Marra, a conservation biologist at Georgetown University in Washington, D.C. The loss is widespread, he says, affecting rare and common birds alike. “Our study is a wake-up call. We’re experiencing an ecological crisis.”
By analyzing the 12 databases built from decades of on-the-ground bird observations in the United States and Canada, Rosenberg, Marra and their colleagues built a record of population-level changes in 529 species which represents about 76 percent of birds populations that breed in North America. Analysis of these data helps them to estimate the population trends since 1970 and compare them with the current population size.
This result shows nearly 1 in 3 birds or about 29 percent of the birds have vanished in the last half-century. About 700 million Grassland birds including meadowlarks have vanished since 1970 (53 percent declined). Similarly, American sparrows, a quarter or 750 million have disappeared since 1970.
However, the populations of waterfowl, like Canada geese and mallard ducks, have grown by 56 percent in the last five decades. “This increase is no accident,” Rosenberg says. “It’s a direct result of decades of conservation efforts made by hunters and billions of dollars to protect these birds and their habitat,” Rosenberg says he hopes this study will spur similar concern for all birds.
Journal: Rosenberg et al. Decline of the North American avifauna. 2019. Science