Avian Monitoring and Ecological Restoration: A Comparison of Data Collection Methods

Abstract

Oak savanna and grassland prairie habitats are facing significant threats of ecological extinction in the Pacific Northwest. Previously prominent throughout Oregon under the stewardship of Indigenous communities and managed using prescribed fire, oak savannas and prairies experienced major declines after European settlement introduced fire suppression laws in the mid-19th century. As a result, native oak savanna and grassland prairie ecosystems were lost to encroaching conifer woodlands and agricultural development. Now, an estimated less than five percent of native oak savanna and prairie ecosystems remain, and associated bird species are among the most threatened avian populations in Oregon. For the conservation of these species, the restoration of oak savanna and grassland prairie habitats is of the greatest concern. The Howard Buford Recreation Area is a public recreational park managed by local organizations with the mission to restore native oak savanna and prairie ecosystems using traditional prescribed fire. Previous research conducted by the Environmental Leadership Program-sponsored Wildlife and Parks team at the University of Oregon evaluated the effects of park management methods on oak savanna and prairie bird behavior. This thesis expands on the Wildlife and Park team’s research and investigates the efficacy of different avian monitoring methods as an indicator of ecosystem restoration progress. This research compares the Wildlife and Park team’s five-minute point count methodology to data collected by an Autonomous Recording Unit (ARU). I evaluated the species detection of both by analyzing the richness of ARU species lists constructed using the same five-minute periods as the point counts. The mean number of species detected by the ARU (12, SE 2.7) was significantly higher than that of the Wildlife and Park team’s point count data (9, SE 1.0) (p = 0.054, n = 4, α = 0.1) during the designated pre- and post-treatment data collection periods. For three out of the four compared data collection periods, the ARU detected more species than the point counts; the only exception occurred on May 31st when both methods detected the same number of species. Additionally, during pre- and post-treatment periods, the ARU detected multiple oak savanna- and prairie-associated species relevant to the study that the point counts missed. Further, over the course of its total recorded hours, the ARU detected two important, at-risk oak savanna/grassland species previously missed in the Wildlife and Parks team’s point count data collection (Acorn Woodpecker and White-breasted Nuthatch) that are crucial to the evaluation of HBRA’s ecosystem restoration progress. This thesis concludes that ARUs are an accurate, efficient, and excellent source of avian data collection and can serve as useful tools in ecological restoration areas by detecting bird species that indicate oak savanna and grassland prairie habitat wellness. For maximum detectability and accuracy, I recommend using ARUs and point counts in tandem. Together, both methods provide a more holistic glimpse into avian populations and, therefore, ecosystem health. This thesis includes collaboratively produced work.