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Illinois Department of Natural Resources
February 2022
February 1, 2022
Photo by Patty Gillespie.

Wildlife-driven Conservation Practices Benefit Grassland Birds

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By Kathy Andrews Wright
A close-up of a pink flower with a small bee in its center. In the background is lush green vegetation.
Photo by Patty Gillespie.

Scattered within the summertime sea of big bluestem, Indiangrass and switchgrass, pollinators nectar on wild bergamot, common milkweed, marsh blazingstar and mountain mint. Bright-yellow blossoms of partridge pea attract an assortment of the long-tongued bees responsible for cross-pollinating plants, which will soon be laden with nut-brown seed pods. A grasshopper sparrow makes a sudden appearance, nabbing a grasshopper for a hungry clutch of nestlings hidden in a domed nest at the base of a grass clump. Scratching and pecking on bare patches within vegetation, a hen bobwhite and her brood hunt for protein-rich beetles, ants and crickets. Goldenrods and New England aster show promise of future blossoms that will provide critical late summer and fall foods for butterflies and bees.

This grassy strip lies between an agricultural field and a woodland edge and provides food, cover and shelter for a host of organisms. This habitat buffer exists as a result of a Conservation Reserve Program practice known as a CP33.

A small blue bird perches on a stem. In the background is a yellow flower.
Photo by Jim Hudgins, USFWS.

Implemented by the USDA-Farm Service Agency in 2004, the Habitat Buffers for Upland Birds (CP33) practice was the first federal practice to target species-specific populations under the Continuous Conservation Reserve Program (CRP). The initial program entailed enrollment and management of 250,000 acres across 35 states for a 10-year period. 

CP33 entails establishing 20- to 160-foot vegetative borders, or habitat buffers, around agricultural fields. Buffers of native grasses and legumes provide habitat for northern bobwhite, ring-necked pheasant and other grassland-dependent birds, many of which are experiencing significant population declines. Buffer strips also are beneficial in reducing soil erosion and improving water quality by trapping sediments and nutrients. 

A chart indicating the increase in grassland birds in buffer strips along agricultural fields from 2006 to 2009.
Bird abundance and richness on established habitat buffers in Illinois during the initial CP33 monitoring effort.

CP33 is a continuous, 10- to 15-year sign-up program, meaning farmers can join at any time. As of October 2021, 45,000 acres were enrolled in CP33 in Illinois, spanning all corners of the state.

“Illinois leads the nation in terms of participation, followed by Texas,” noted Wade Louis, Illinois Department of Natural Resources (IDNR) Habitat Team Program Manager and Acting Agricultural and Grassland Program Manager. “With 27 million acres of agricultural land in Illinois, or 75 percent of our total land base, it makes sense that Illinois is leading in participation in a program that encourages farmers to put habitat strips along what often is marginal ground adjacent to fencerows, waterways, woodlands and other cover types.”

A graphic with text providing information about the first wildlife-driven USDA program that was so well received that two additional programs were developed. At the top of the graphic is a photo of a green combine harvesting along an agricultural field. In the foreground is a group of purple flowers.
Photo by Patty Gillespie.

“State participation in the program initially required monitoring grassland bird responses over a 3-year period,” Louis explained. “In Illinois, monitoring was coordinated by former Agricultural and Grassland Program Manager John Cole, with IDNR District Biologists conducting counts within their district. During the spring breeding season, biologists conducted designated point counts, stopping and recording all birds seen and heard over a set amount of time.”

The result of these inventories assessed bird abundance and richness on established habitat buffers (see graph). 

One species benefitting from CP33 buffer strips is the northern bobwhite, an upland game bird whose population has steadily declined since the 1930s due to habitat loss, degradation, fragmentation, and in Illinois, changes to land use due to more intensive agricultural practices. In the August 1, 2019 OutdoorIlinois Journal article Bobwhites Hanging on in Southern Illinois, authors Caleb S. Crawford and Michael W. Eichholz noted that “across their range bobwhites have experienced declines of 4.2 percent per year. In Illinois specifically, bobwhites have been declining at a rate of 3.3 percent per year based on the North American Breeding Bird Survey.”

A summary of the national CP33 bobwhite and upland songbird monitoring efforts was published in December 2009. Researchers noted a “substantively greater density of breeding male bobwhites and fall bobwhite coveys on CP33 fields compared to unbuffered fields in each year from 2006 to 2008” and that “overall bobwhite density was 70 to 75 percent higher on CP33 fields compared to unbuffered fields.” As far as the response of upland songbirds, dickcissels, field sparrows and indigo buntings showed a strong overall response in at least two of the years sampled. Vesper sparrows, eastern meadowlarks, grasshopper sparrows and eastern kingbirds showed variable to no annual response.

A small brown, tan, and black bird stands in a dusty spot in an agricultural field.
Photo by Dave Menke, USFWS.

A report on the final results of the nationwide CP33 grassland bird monitoring effort (Conservation Reserve Program CP33 – Final Report 2006-2011) noted that “The observed response validates an underlying assumption of the National Bobwhite Conservation Initiative (NBCI), that a relatively small (5-15 percent) change in primary land use in agricultural landscapes can disproportionately influence population response in some regions. Presuming greater densities on buffered fields represent net population increases rather than redistribution of existing populations from the surrounding landscape, CP33 may have the capacity to affect large-scale population changes in some declining bird species. However variable response to CP33 by species and across regions highlights the need for an understanding of ecological processes underlying observed differences in density.”

A songbird with a yellow bib and brown wings is in mid-song while perching on a stem of a yellow flowering plant. In the background is green vegetation.
Photo by Michael Jeffords.

“Overall, CP33 has proven to be an excellent program with regards to soil conservation, water quality protection and wildlife habitat enhancement,” Louis said. “Multiple studies have shown that wider strips result in the greatest wildlife diversity and species abundance, and that such strips are more beneficial to farmers by removing marginal land from production. Buffer strips are a win-win program, benefiting both the farmer and wildlife.”


Kathy Andrews Wright is retired from the Illinois Department of Natural Resources where she was editor of Outdoor Illinois magazine. She is currently the editor of Outdoor Illinois Wildlife Journal and Illinois Audubon magazine.

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