When I heard the news that it was okay to feed the birds again, I poured shelled sunflower seeds into the throat of my Squirrel Buster Classic and hung it on the shepherd’s crook in my backyard. And then I returned to my screened porch, sat down and waited.

How long would it take for the birds to figure out the free food was back?

It’s been more than two months since area wildlife agencies recommended that people take down their feeders, a safety measure meant to stop the spread of a mysterious illness. People were finding dead birds on the ground. Blind birds, too, their eyes crusted and swollen shut.

It was creepy. It was scary. It was exactly what we didn’t need at a time when we humans were dealing with our own pandemic.

“It’s like ‘The Stand’ or something,” said Dan Rauch, fisheries and wildlife biologist in the District’s Department of Energy and Environment, referencing Stephen King’s post-apocalyptic novel. “You see three or four dead grackles on the street, it starts to add up. It’s not everyone’s inclination when they see a dead bird to run and pick that up. In the days of covid, you’re not even sure you’re supposed to open the door.”

But people did pick them up. Birds — dead ones, blind ones, primarily fledglings suffering from the unknown ailment — were brought to animal rehabilitators, veterinarians, and state and local wildlife officials. Agencies large and small — from the U.S. Geological Survey to City Wildlife in the District — shared information.

“It was amazing that all these labs could collaborate, all these states, all these citizen scientists, all these wildlife rehabilitation groups,” Rauch said.

These strong networks will help the next time there’s a bird die-off. That’s good. What’s not so good is that there may be a next time. Experts still aren’t sure what happened this time.

“It’s probably a virus, but we don’t know what it is,” said Bruce Beehler, a research associate in the division of birds at the Smithsonian’s National Museum of Natural History. “It’s been sent to a bunch of labs and yet they can’t isolate it.”

Debi Klein runs the Backyard Naturalist in Olney, Md., where she sells bird feeders, birdhouses, seed, suet and other bird-related stuff. Due to the feeding moratorium, business was understandably down this summer. She has some thoughts on the disease’s origins.

“It started with the cicadas and ended with the cicadas,” she said. “It’s hard to believe there’s no correlation.”

Klein can’t help but wonder if people who sprayed their bushes with pesticides to kill Brood X cicadas wound up poisoning birds.

Fledgling season is largely behind us. Since it was mainly fledglings that were affected, that may be why mortality is down and it’s safe to sound the all-clear.

“Will it come back next spring?” asked Beehler. “We don’t know. That’s the worry.”

For now at least, we can hang our feeders again. We just have to make sure they’re clean and that we keep them that way.

The Maryland Department of Natural Resources recommends cleaning feeders and birdbaths at least once a week with soap and water, disinfecting with a 10 percent bleach solution, rinsing well with water and then air-drying. Wear disposable gloves and wash your hands when finished.

The seed itself should be clean, too. Make sure it’s stored in a cool, dry place.

“Now is the time of year when mold builds up, with all the rain and humidity,” Klein said. “You’ve got to be very careful about that.”

The seasons are about to change. Songbirds are getting busy. The last of the nesters — goldfinches, bluebirds — are seeing off their offspring. Hummingbirds who summer in the north are passing through on their way south. Our hummingbirds are filling their bellies and packing on weight for their journey. (Put out those nectar feeders, too.)

Said Klein: “With the loss of habitat all over the country, our backyard mini-habitats become sanctuaries, particularly during nesting season and during cold weather, when nothing else is available.”

Even though Beehler has studied birds all over the world, he still enjoys seeing them in his backyard in Bethesda, Md.

“The joy that birds bring us is real,” he said. “When you lose that connection, as we did in the last couple of months, it’s sort of hurtful. I’m happy to be back with the birds. I know for lots of people, birds provided a new sense of relief from the pandemic. I think that made it doubly troubling to be cut off from that source of joy.”

About 40 minutes after I put up my bird feeder on Tuesday morning, a male cardinal alighted on the bottom perch and started enjoying beakfuls of seed.

Welcome back, my friend.

Twitter: @johnkelly

For previous columns, visit washingtonpost.com/john-kelly.