Understanding Avian Habitat Availability and Use After Barrier Island Restoration in Coastal Louisiana

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Using ecological and geographical data, WARC researchers and their partners are analyzing avian and benthic sampling on Whiskey Island and Caminda Headland to compare pre- and post-restoration aspects of habitat occupancy, habitat availability, habitat use, and kernal density estimation.

Whiskey Island and Caminada Headland

Whiskey Island prior to restoration (a; imagery from the U.S. Geological Survey [USGS], 2016) and post-restoration (b; imagery from the Louisiana Coastal Protection and Restoration Authority, 2018). Caminada Headland prior to restoration (c; imagery from the USGS, 2012) and post-restoration (d; imagery from the USGS, 2018). Location of the two sites in coastal Louisiana (e).

The Science Issue and Relevance: Barrier islands provide resources and ecological services that are integral to economic and environmental interests, such as protection of coastal infrastructure and providing habitat for wildlife. Therefore, it is imperative that barrier island systems are managed in a way that ensures these systems remain resilient and continue providing ecosystem goods and services, such as sustaining critical wildlife populations over time. However, evaluation of how management actions, such as restoration, and subsequent natural ecological processes impact species of conservation concern is a daunting challenge. This information would allow land managers to target restoration activities that produce the best outcome for multiple stakeholders, including enhancing island sustainability and preserving habitat availability, especially habitat needed by species of conservation concern. We are investigating habitat occupancy and use/function for several focal species on Whiskey Island and Caminada Headland in Louisiana to determine how patterns of distribution, abundance, and behavior change before, during, and after restoration. We also aim to identify how restoration activities influence habitat availability for birds throughout the annual cycle that includes the migratory, wintering, and nesting seasons.

Methodology for Addressing the Issue: Analyses will largely center around several focal bird species surveyed on Whiskey Island and Caminada Headland, which include: piping plover (Charadrius melodus), snowy plover (Charadrius nivosus), Wilson’s plover (Charadrius wilsonia), red knot (Calidris canutus), and American oystercatcher (Haematopus palliatus). On Whiskey Island, avian surveys began in 2012 and concluded in 2020, providing data on bird distribution and abundance before (2012–2017), during (2017–2018), and after the restoration period (2018–2020). Benthic sampling was performed on Whiskey Island from 2013–2015 and in 2019-2020. For more information about the Whiskey Island restoration project, please see: https://cims.coastal.louisiana.gov/outreach/projects/ProjectView?projID=TE-0100. At Caminada Headland, avian surveys began in 2012 and finished in 2018, providing data on bird distribution and abundance before (2012–2013), during (2013–2016), and after the restoration period (2016–2018). Benthic sampling was performed at Caminada Headland from 2013–2016 and 2018–2019. For more information about the Caminada Headland restoration project, please see: https://coastal.la.gov/project/caminada-headland-beach-and-dune-restoration/. We will characterize barrier island habitat using existing high-resolution orthophotography, cloud-free satellite imagery, available elevation data from light detection and ranging (LiDAR) and real time kinematic (RTK) project as-built information to produce habitat maps using the Louisiana Barrier Island Comprehensive Monitoring Program (BICM) classification scheme and methodology. Using ecological and geographical data, we will compare pre- and post-restoration aspects of habitat occupancy, habitat availability, habitat use, and kernel density estimation.

Future Steps: After completing the habitat maps and analyses described above, we will be working to share this information with our partners at the Coastal Protection and Restoration Authority (CPRA), other coastal managers (e.g., U.S. Fish and Wildlife Service, Louisiana Department of Wildlife and Fisheries), and the overall scientific community through presentations, reports, and journal articles. The analytical results and GIS products we produce will be critical to the future restoration and management of coastal habitats in Louisiana and the overall northern coast of the Gulf of Mexico given the amount of current and anticipated restoration projects in the region.

Avian occupancy on Whiskey Island

Avian occupancy on Whiskey Island

Potential change in Wilson’s plover occupancy and habitat use, indicated by circles, on Whiskey Island (above) before (5/16/2017) and (below) after (6/30/2018) restoration. Circle diameter scales with number of individuals.