Strata boundaries for nesting Wedge-tailed Shearwater (Ardenna pacifica) surveys at Kīlauea Point National Wildlife Refuge, Kauaʻi, in 2019

We used a stratified-random sampling approach to estimate the total abundance of Wedge-tailed Shearwater (Ardenna pacifica) nest sites across Kīlauea Point National Wildlife Refuge (KPNWR), Kauaʻi, during 1-7 July 2019. We first identified strata as unique geographic areas of the refuge to account for potential differences in nesting habitat and non-uniform nest site clustering. We then sub-divided strata where we expected high, low, minimal, or no nest site abundance. These distinctions were based on knowledge of shearwater nesting distribution gained while performing extensive ground-searching for tropicbirds across the entire refuge in April and May 2019. We delineated strata boundaries using recent satellite imagery in ArcGIS (version 10.7) and, based on direct observations in the field, refined in order to remove large contiguous areas lacking shearwater presence or nesting habitat. Planar area of each polygon was automatically calculated by ArcGIS. To calculate surface area in each stratum, we obtained a 1/3 arc-second (10-m resolution) digital elevation model from the National Elevation Dataset (USGS 2013). This elevation raster was projected to Universal Transverse Mercator projection (Zone 4 North, North American Datum 1983) and converted to a surface area raster using the raster and sp packages in R (Hijmans 2019; Pebesma & Bivand 2005). We calculated stratum-specific surface area by summing the surface area values of raster cells in each stratum using XToolsPro (version 18; Zonal Statistics tool) in ArcMap (version 10.7). Hijmans RJ. 2019. raster: Geographic Data Analysis and Modeling. R package version 3.0-7. https://CRAN.R-project.org/package=raster Pebesma EJ, Bivand RS. 2005. Classes and methods for spatial data in R. R News 5(2):9-13. U.S. Geological Survey. 2013. USGS NED n23w160 1/3 arc-second 2013 1 x 1 degree ArcGrid: U.S. Geological Survey. Accessed at https://www.sciencebase.gov/catalog/item/581d21dae4b08da350d53be2

Data and Resources

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metadata_created 2025-11-20T22:25:27.862997
metadata_modified 2025-11-20T22:25:27.863002
notes We used a stratified-random sampling approach to estimate the total abundance of Wedge-tailed Shearwater (Ardenna pacifica) nest sites across Kīlauea Point National Wildlife Refuge (KPNWR), Kauaʻi, during 1-7 July 2019. We first identified strata as unique geographic areas of the refuge to account for potential differences in nesting habitat and non-uniform nest site clustering. We then sub-divided strata where we expected high, low, minimal, or no nest site abundance. These distinctions were based on knowledge of shearwater nesting distribution gained while performing extensive ground-searching for tropicbirds across the entire refuge in April and May 2019. We delineated strata boundaries using recent satellite imagery in ArcGIS (version 10.7) and, based on direct observations in the field, refined in order to remove large contiguous areas lacking shearwater presence or nesting habitat. Planar area of each polygon was automatically calculated by ArcGIS. To calculate surface area in each stratum, we obtained a 1/3 arc-second (10-m resolution) digital elevation model from the National Elevation Dataset (USGS 2013). This elevation raster was projected to Universal Transverse Mercator projection (Zone 4 North, North American Datum 1983) and converted to a surface area raster using the raster and sp packages in R (Hijmans 2019; Pebesma & Bivand 2005). We calculated stratum-specific surface area by summing the surface area values of raster cells in each stratum using XToolsPro (version 18; Zonal Statistics tool) in ArcMap (version 10.7). Hijmans RJ. 2019. raster: Geographic Data Analysis and Modeling. R package version 3.0-7. https://CRAN.R-project.org/package=raster Pebesma EJ, Bivand RS. 2005. Classes and methods for spatial data in R. R News 5(2):9-13. U.S. Geological Survey. 2013. USGS NED n23w160 1/3 arc-second 2013 1 x 1 degree ArcGrid: U.S. Geological Survey. Accessed at https://www.sciencebase.gov/catalog/item/581d21dae4b08da350d53be2
num_resources 2
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title Strata boundaries for nesting Wedge-tailed Shearwater (Ardenna pacifica) surveys at Kīlauea Point National Wildlife Refuge, Kauaʻi, in 2019