Doctoral Dissertations

Date of Award

5-2025

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Natural Resources

Major Professor

Patrick D. Keyser

Committee Members

Joseph Clark, David Buehler, James Martin

Abstract

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 2nd-order scale. This was corroborated by 3rd-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.

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