The rain kept falling, but the birds kept singing. So the watchers stayed at their post, keeping count.

Chickadee. Flicker. Pileated woodpecker. Yellow-bellied sapsucker.

Each name went into the notebook. By midday, they’d logged 17 different species in one small clearing in the Mississippi National River and Recreation Area. If they were lucky, they’d add a few dozen more by nightfall.

This was the Big Sit, a chance for bird watchers to plant themselves in one spot for a day and see what the great fall migration would bring their way.

They celebrated every bird they could see, under skies that seem emptier than they used to be.

North America lost 3 billion birds over the past 50 years, according to a recent report from Cornell University.

The news came as no surprise to Minnesota bird watchers, accustomed to long searches for species we once took for granted.

Warblers. Finches. Bluebills. Blue jays. Sparrows. Red-winged blackbirds. Meadowlarks.

“Where are our meadowlarks?” farmers asked Steve Weston, as he crisscrossed western Minnesota, gathering data and making notes of nesting sites for an atlas of breeding birds. “We used to hear meadowlarks all the time, and they’re gone.”

The bright yellow meadowlarks are still out there, serenading the farmers. But every year, the choir gets quieter. Western meadowlark populations have declined 1% a year, every year, as climate changes and habitat loss wear away at the species.

“There were still meadowlarks out there, but their numbers were so few by comparison to what they used to be,” Weston said. “Farmers were noticing that these birds whose songs they used to enjoy while they were out working the fields, they weren’t there anymore.”

It happened so gradually, most of us didn’t notice that a quarter of our birds had gone missing from our skies. They weren’t going extinct. Not yet. They were just going away.

More than 200 bird species make their homes in Minnesota for at least part of the year. More than half those species are in decline.

Lesser scaup, once one of the state’s most popular and plentiful waterfowl, are being sickened by the invasive zebra mussels in our lakes.

In the woods, invasive buckthorn is crowding out native plants, and the insects that feed on those plants, and species like chickadees, that feed on those insects.

We lost 95% of our redheaded woodpeckers. If you want to see one, you can visit the Cedar Creek Conservation Area, where they preserved a tiny corner of Anoka County’s native landscape of tall grass and oak groves — and saved a thriving woodpecker colony in the process.

Not every bird species is struggling, said Luis Ramirez, the Audubon Society’s director of conservation for the Upper Mississippi Flyway. Many game species are thriving in protected habitats, but even the most beloved species could face hard times ahead.

By 2080, Audubon estimates, common loons could lose most of their winter range to climate change.

“Minnesotans have such a strong connection to their wetlands and their lakes and their waterways,” Ramirez said. Will that connection be as strong without the sound of loons and yellow rails at sunset?

“Our experience of how we enjoy these lakes,” Ramirez said, “for sure is going to change.”

It’s not too late to save what we have.

The birders at the Big Sit gathered at Coldwater Spring — a onetime mine site that has been cleared of old buildings and invading buckthorn and turned back over to the birds and the bugs and the plants and the people who love them.

You can find indigo bunting there now. Golden-crowned kinglets. Birders held their breath Saturday, hoping for a fox sparrow sighting.

They pulled that off at Coldwater Spring — just off the Hiawatha Parkway, right next door to an off-leash dog park.

If they can do it, maybe we could restore the prairie pothole wetlands we plowed under and the oak savannas we built over.

We could use window decals to minimize bird crashes, and plant native species in our yards and stop using pesticides.

We could keep our songbird-gobbling cats inside, no matter how much they meow.

We could pull on our warmest, longest underwear and join the annual Audubon Christmas bird count this December.

Because if we’re going to bring the birds back, we need to see what we’re missing.

To read the Cornell study, visit: birds.cornell.edu/home/bring-birds-back.