Northern bobwhite and grassland-associated birds benefit from native-warm season grasses in a working landscape dominated by cool-season grasses

Most North American avian species populations have been declining since at least 1966. Grassland-associated species in the southeastern US have experienced some of the most drastic declines, primarily due to widespread loss of habitat. The northern bobwhite (Colinus virginianus; “bobwhite”) has also been affected by these changes and has declined by about 85% since 1966.

This loss has partly been attributed to the widespread conversion of native grassland to tall fescue (Lolium arundinaceum), a cool-season grass (CSG) native to Europe. In the Fescue Belt region of the southeastern US, about 14 million ha of tall fescue are managed as a forage for livestock as pastures and hayfields. Traditional pasture management creates a grassland that lacks many structural and compositional characteristics that native fauna are adapted to.

Biologists have recommended native warm-season grasses (NWSGs) as an alternative forage that may benefit both cattle and wildlife. However, few experiments have tested hypotheses about wildlife in a working-lands context, where there is a conservation benefit without a loss in agriculture. I conducted a study in eastern Kentucky, USA to evaluate resource selection and survival of bobwhites, and occupancy of bobwhites and grassland birds among NWSGs and CSGs in a working lands context. Between April 2019 and October 2022, I tracked bobwhites using radio telemetry and surveyed for avian breeding season occupancy.

Bobwhites selected traditionally managed CSG less than expected and NWSG more than expected at the 2^nd-order scale. This was corroborated by 3^rd-order selection of NWSGs, woody stems, and taller canopies, while avoiding high proportions of grass. Variation in breeding season and non-breeding survival was explained by an interaction of grazed NWSG and shrub interspersion-juxtaposition index (“iji”). Occupancy of bobwhites was greater in grazed NWSG than idle-burned NWSG and CSG-dominated areas. Henslow’s sparrow (Ammodramus henslowii) occupancy was greater with increasing grazed NWSG cover and decreasing shrub cover. The results of this study suggest NWSGs in a CSG-dominated landscape may contribute to conservation of bobwhites and other grassland birds. However, shrub cover and interspersion should be considered an important factor when planning species-specific conservation.