75 percent of North America’s bird species are in decline, study says

Great egrets and little blue herons. Blue-winged warblers and yellow-bellied sapsuckers. Snowy owls and tropical kingbirds.

Across North America, three-fourths of bird species are in decline, according to a sweeping study of avian populations published Thursday, the latest sign of a slow-moving extinction crisis that threatens entire ecosystems.

The population losses among the continent’s birds — red-winged blackbirds belting conk-la-ree! in marshlands, chickadees gathering around suburban bird feeders, peregrine falcons swooping between skyscrapers — should serve as a canary in the coal mine for people who live alongside birds, scientists say.