Minnesota farmers have withdrawn hundreds of thousands of acres from the government's biggest conservation program in the last decade, shifting land that was set aside for grasses and wildflowers back into corn, soybeans and other crops.

As a result, the state has lost about 1,200 square miles of protected land — an area the size of Rhode Island — that was key habitat for Minnesota's prized pheasants, ducks, jack rabbits and a variety of pollinators.

The state's wildlife populations have declined in tandem with that shift and are unlikely to recover unless habitat is restored, said Tim Lyons, an upland game research scientist at the Minnesota Department of Natural Resources.

"This is kind of what we expect now, given how habitat and farming practices have changed," he said.

Enrollment in the Conservation Reserve Program (CRP), which was created under the federal farm bill in the 1980s, peaked nationwide and in Minnesota in 2007. That year Minnesota farmers enrolled more than 1.8 million acres. But as demand for corn and soybeans grew over the past decade, farmers pulled land out of conservation leases and Minnesota enrollment has fallen steadily, to just over 1 million acres last year.

The state's pheasant population has fallen in lockstep with it — as hunters are likely to notice this weekend with the opening of the fall pheasant season.

"It's a simple equation," said Jared Wiklund, spokesman for Pheasants Forever, a prominent supporter of the CRP. "When you have more grasslands, and average weather, pheasants will respond."

The CRP pays farmers a fee per acre to retire underperforming or marginal land for a certain number of years and plant it with native grasses and wildflowers. In addition to providing prime wildlife habitat, the restored land cuts carbon emissions, prevents soil erosion and protects the state's lakes, streams and rivers from chemical runoff.

The protections, however, are temporary by the program's very structure. The federal government typically leases the retired land for a 10-year period. Once that lease is up, farmers are free to return the land to production.

As a result, CRP enrollment has typically swung with crop prices, said Ferd Hoefner, senior strategic adviser for the National Sustainable Agriculture Coalition. When commodity prices are low, farmers set aside some of their worst land because the CRP gives them a guaranteed income on it. But when prices rebound, even marginal cropland yields a better return than the government's conservation payment.

"A fundamental problem in the Dakotas and Minnesota is that the farming economy got real hot for a while with the ethanol standards [which raised demand for corn] and a lot of farmers wanted to get out of CRP," Hoefner said. "Now maybe they're regretting that choice, with prices in the toilet and all these years of flooding."

Across Minnesota, DNR biologists, game wardens and volunteers have been traveling down the same gravel roads and quiet routes every August since 1955 to survey a key environmental indicator: pheasant populations.

Their findings this year were bleak.

In Cottonwood County, where spotters counted more than 200 pheasants a decade ago along the roadsides and fringes the birds seem to love, the surveyors found just over a dozen this year. To the west in Pipestone County, where about 120 pheasants were seen every year in the mid-2000s, the researchers are now lucky to spot 25.

Altogether, Minnesota's pheasant population is estimated to have dropped 60% from its long-term average.

The primary reason is habitat loss, Lyons said. Pheasants and other grassland birds and prairie species prefer dense, grassy fields that give them cover for nesting and lots of insects for feeding. With so many of those acres converted to weed-free rows of corn, hunters may find dramatically fewer birds than in years past.

While many wildlife and conservation groups have pressed to expand the CRP, some environmental groups have been more guarded. They worry about the sheer cost of the program — some $2 billion in recent years — for habitat gains that, while significant, are only temporary.

"This is a completely predictable tragedy," said Trevor Russell, water program director of the Friends of the Mississippi River, of the recent decline in CRP acres.

Politicians, too, have noticed the program's cost. As demand for the CRP fell in the last decade, Congress reduced the cap on nationwide enrollment, cutting it from 37 million acres to a low of 24 million in 2014. The latest farm bill, passed in 2018, raised the cap slightly, to 27 million acres in coming years. The U.S. Department of Agriculture is expected to hold a general enrollment period in December.

Russell said it would be impossible to significantly ramp up the program now, because while crop prices may fluctuate, land has continued to get more expensive and farmers need to earn a return on it. More significant and permanent gains for water quality, soil health and habitat at some point need to be market-driven, he said.

"CRP is a tool, and it's a good tool, but to really get the environmental outcomes we want, we would need to convert millions of acres in Minnesota," Russell said.

Idling that much land would be "too much for our economy to handle," he added. "So what we need is to transition to a market that demands more continuous vegetation [such as cover crops and perennials] on the landscape, which can get us water quality benefits while farmers are making money."

The saving grace for pheasants in Minnesota is that while fewer acres are enrolled, the CRP has been updated, so that the land restoration will be of better quality, Wiklund said.

"As it has evolved, it's requiring more diversity and flowering plants and grasses," he said. "It's much more resilient land, with more insects, which feed more chicks. If we can just get slow and steady increases to CRP and even average weather, the pheasants will be fine. The glory days aren't behind us."