Over a ledge off the 26th floor of one of St. Paul’s tallest buildings, a peregrine falcon swooped past her nest while her mate soared high above and called out to her.

Lori Naumann, with the Department of Natural Resources nongame wildlife program, was protected by a screen as she checked the nest for eggs and wiped a camera monitoring the pair. The falcons, the world’s fastest living things, continued to hover and dive in the biting wind, ready to fight for what might be the city’s finest nesting spot.

“I think if we were outside, we’d be injured by now,” Naumann said.

The nest would have been almost unimaginable a few decades ago, when there were no peregrines known to be left in the Minnesota wild. But now, the program largely responsible for helping them make a comeback is at risk as fewer and fewer taxpayers donate money to help keep it running, biologists say.

The state’s nongame wildlife fund, which also helped restore bald eagles and trumpeter swans from the brink of extinction in Minnesota, has been almost entirely funded through checkoff donations marked on tax returns since the 1980s. In the early years of the program, when wild swans hadn’t been seen near the metro for a century and eagle sightings were so rare as to be newsworthy, about 200,000 people a year would check the box on their state returns to give at least a few dollars to the program.

By 1995, half that number donated. In 2015 — the last year the state kept records on the donations — fewer than 50,000 people contributed. And that number has probably steadily decreased in the years since, Naumann said.

“We’re worried because as far as we can tell it’s the same people who are donating every year and as they get older they’re just not being replaced,” she said.

Minnesota is hardly alone. A total of 30 states set up similar tax donation-based programs in the 1970s and ’80s — known as the “chickadee checkoff.” Many, including Iowa, Indiana and Ohio, have seen sharp drops in donations over the past decade.

State Rep. Rick Hansen, DFL-South St. Paul, said it’s time to see if there are ways the state could better promote the program to taxpayers, or ensure that accountants or online tax programs are prompting people when they file. Hansen, who chairs the Legislature’s environment and natural resources finance division, said he plans to set up a hearing on program funding.

“We have to keep reengaging people and we have to keep promoting it,” Hansen said. “The problem with legacy programs like this is that people assume they’re chugging along when sometimes they need help.”

Checkoff donations may no longer make sense as more people file their income taxes online and possibly miss the prompt or click out of it like an unwelcome ad, said Don Arnosti, executive director of the Minnesota division of the Izaak Walton League.

“I still do my taxes by hand, but my millennial daughter did hers online and never even saw the checkoff,” Arnosti said. “The way the world functions has shifted.”

Arnosti said he fears there may also be another type of generational shift at work: Younger people may not know what they’re missing.

In the same way that there is no living memory of what it was like to once see a million passenger pigeons flock overhead, most Minnesotans today have probably never seen a redheaded woodpecker, or certain warblers. Even further down the food chain, the insects that feed young pheasants and are essential for migratory birds are diminishing, he said.

“I was on a long drive last summer, from South Dakota back to St. Paul, and I realized when I got home I never once had to stop to clear the bugs off my windshield,” Arnosti said. “Ask someone my age about that. When we were young, on a summer night, you had to stop every 50 miles to clean your windshield.”

There are two silver linings for the wildlife fund.

The first is that the taxpayers who are donating have been contributing more, which has kept funding relatively stable at about $1 million each year since 2007. Those donations are matched with funds raised from specialty wildlife license plate sales, giving the program roughly $2 million a year to operate.

The second is that people from across the country and beyond are falling in love with the program’s eagle cam, a live feed of a female bald eagle and her mate that have been struggling to hatch chicks each spring at the same nest in an undisclosed location.

The live feed, which has now drawn viewers from all 50 states and more than 160 countries, includes a donation link, providing the wildlife fund its first revenue source outside of tax season — about $50,000 a year, Naumann said.

Time will tell if public interest in the iconic raptors, whose near-extinction sparked the creation of the nongame program, can once again gin up enough support to fund restoration efforts for the loons, woodpeckers and migratory birds that now need it.