Using eDNA and Habitat Suitability Modeling to Better Understand the Range and Habitat Requirements of the Eastern Black Rail

ECU Author/Contributor (non-ECU co-authors, if there are any, appear on document)

Amberly Neice (Creator)

Institution

East Carolina University (ECU )

Web Site: http://www.ecu.edu/lib/

Abstract: The Black Rail (Laterallus jamaicensis) is a marsh bird that is globally listed as Near Threatened and is being considered for listing under the federal Endangered Species Act. This species has experienced concerning population declines throughout its range. Black Rails are difficult to detect due to their small size, concealing habitat, and cryptic behavior. The most common survey method for rails uses audio callback but does not detect unresponsive individuals, is constrained seasonally as well as temporally, and requires significant personnel effort. New methods are needed to provide information on the distribution and habitat requirements for this threatened species. Here, I describe a novel detection method for Black Rail using environmental DNA (eDNA) and an ecological niche model identifying areas and characteristics of suitable habitat for this species. To detect Black Rail eDNA I developed a qPCR assay that targets a 219-bp region of the cytochrome c oxidase subunit 1 gene (COI) and uses a fluorescent reporter probe to increase specificity. The assay reliably produces a signal when sufficient copies of Black Rail template are present, and does not produce signal when tested for cross-species amplification using genomic DNA from sympatric rail species. The assay successfully amplified Black Rail eDNA from environmental samples taken from locations with positive detections. I tested statistically whether various environmental factors, as well as sampling and handling variables, affected eDNA detectability. Among the factors tested for their influence on amplification success (time between collection and DNA extraction, storage temperature before filtering, field detection method (audio, visual, camera trap, none), time between detection and sample collection, water salinity, and air temperature), only water depth was found to have a significant effect. I also created a habitat suitability model for the Eastern Black Rail focusing on the Atlantic coastal plain using eBird data contributed by citizen scientists and environmental variable data from the Esri databank using a maximum entropy model framework. The map generated by the MaxEnt model indicated habitat suitability in areas known for Black Rail occupation. The environmental factors that best predicted Black Rail presence were flooded areas of shrub and herbaceous vegetation, proximity to water, and flat plains. These environmental variable associations were congruent with other habitat association studies conducted in other parts of the species" range that focused on smaller areas and used presence data collected through surveys. My habitat suitability model had comparable statistical parameters to other MaxEnt models created for birds. Correlation with known areas of Black Rail occupation and previous habitat associations confirms the validity of the model and importance of high marsh habitat for the species. The uses of eDNA adds a novel tool to the avian conservation toolbox that can be improved and adapted for other species of concern. The habitat suability model provides a starting point for land management and habitat restoration efforts for Black Rail now and in the future. The information gained using these two techniques can add much needed insight into the range and ecological needs of this imperiled species.

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Language: English

Date: 2020

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