Dutch scientists report that populations of a migratory species called the pied flycatcher have plummeted an astonishing 90% over the past two decades because of climate change.

Even after an unusually mild winter, the return of spring to North America feels like a blessing. Parents are dragging their toddlers to the park. Students are dusting off their Frisbees. And bird watchers, armed with binoculars and guidebooks, are heading out to search for their favorite species.

But…