Date of Award
8-1-2026
Degree Name
Master of Science
Department
Forestry
First Advisor
Pease, Brent
Second Advisor
Holzmueller, Eric
Abstract
The Chuck-will’s-widow (Antrostomus carolinensis) and Eastern Whip-poor-will (Antrostomus vociferus) are nightjar species that inhabit southern Illinois during the breeding season. Both species are thought to benefit from open woodlands which are often a result of natural disturbance or active forest management. However, due to a lack of significant disturbances and active management, this forest structure has become rare. Like many disturbance-dependent species, the Chuck-will’s-widow and Eastern Whip-poor-will have experienced range-wide declines over the past 50 years. Despite this, few studies have examined the impacts of forest management and the resulting forest structure on these species. We evaluated the impacts of burning and midstory thinning on nightjar abundance in upland forests during May–August 2025 in southern Illinois, USA. Fourteen of the 28 sites were managed with varying intensities of midstory thinning and prescribed burning while the remaining 14 sites were not actively managed. Overstory conditions were measured using variable radius plots with a 10BAF Cruz-All and 40m2 fixed radius plots were used for the midstory and understory. Nightjar surveys were conducted by deploying autonomous recording units on nights when lunar illumination was greater than 50%. Vocalizations were identified to species using BirdNET and abundance estimated using time-to-detection n-mixture models. There were no significant differences between basal area and overstory density on managed and unmanaged sites, but there were significant differences in midstory density and ground cover. Eastern Whip-poor-will were detected on 43% of the managed sites and 64% of unmanaged sites, while Chuck-will’s-widows were detected equally across management histories at 14%. Eastern Whip-poor-will abundance significantly declined as the percent of deciduous overstory increased while a non-significant positive trend with overstory density was documented. Due to low detections, models were not fit for Chuck-will's-widow. Ultimately, this study indicates that overstory conditions are likely more important than midstory and ground cover characteristics in territory selection for Eastern Whip-poor-will, and that, in the southern Midwest, Eastern Whip-poor-will may prefer mixed forests over pure deciduous stands.
Access
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