Could more private land conservation reverse bird declines?

Throughout rural Illinois, more than 140,000 acres of farmland have been conserved for wildlife. That’s about as much as one-third the acreage of public land in the state. Like similar programs in other states using federal Conservation Reserve Program dollars outlined in the Farm Bill, Illinois’s program compensates farmers for taking some of their fields out of production to aid wildlife.

“The program is benefiting a wide variety of species,” said Bryan Reiley, avian ecologist with the Illinois Natural History Survey. But when he looked deeper, he found Illinois’s Conservation Reserve Enhancement Program was benefiting some declining bird species more than others. Could CREP lands be harnessed, he wondered, to provide more benefits to more species?

“Based on the numbers we see and other nesting ecology data we have, we know that habitat created through these programs is pretty decent habitat for avian species and many other taxa,” he said. “We just need a lot more of it.”

Field sparrows have increased in abundance in Illinois, but researchers found they lack sufficient habitat to reach state population goals.
©Michael Jeffords and Sue Post

In a study published in Ecosphere, Reiley and his colleagues looked at four bird species to see how well their populations responded to the creation of CREP lands. All four had seen their populations fall by more than 50 percent since 1966. Only two, they found, were close to being recovered: Bell’s vireo (Vireo bellii bellii) and the willow flycatcher (Empidonax trailli trailli).

Two other species — the field sparrow (Spizella pusilla) and northern bobwhite (Colinus virginianus) — were not recovering, despite the conserved landscapes.

In Illinois, CREP seems to work best for birds that prefer successional forest landscapes, the researchers found. Since the conserved lands are often marginal terrain where farmers can’t easily raise crops, they tend to be shrublands that benefit birds like Bell’s vireo and the willow flycatcher, Reiley said.

By increasing restored lands by just 5 percent, the researchers estimated, the willow flycatcher could return to historic levels. The northern bobwhite, on the other hand, would need a 598 percent boost in landscape.

That sounds like a lot, yet given all the agriculture in the state, Reiley said, if just 1 percent of it were converted to CREP, it would likely allow all those species — and probably many more — to return to their historic levels.

That level of protection may not be reachable, he said, but it underscores the important role these agriculture conservation lands can play.

“We need more habitat on the landscape,” he said. “It’s not just bird species. There are a lot of species that have been declining. With more habitat, we’ll have higher populations.”

Read TWS’ technical review on Fish and Wildlife Responses to Farm Bill Conservation Practices.

Header Image: Preserving agricultural land has helped wildlife, but some species have benefited more than others.
©Bryan Reiley