Arctic Coastal Plain Aerial Survey Spectacled Eider Density Estimates, 2007-2023

This is an SQLite GeoPackage simple feature vector database of spectacled eider relative densities predicted from a generalized additive model across the Arctic Coastal Plain. These density are "relative" because year- or observer-specific detection is not incorporated. However, the estimation model include observer as a random effect and predictions are made after removing the effect of observer (i.e., at the average observer). Each year is a separate layer named by year. Predictions are gridded into cells 750m per side but are trimmed to the ACP survey area, so some cells are smaller. For each year, the variable 'fit' gives the expected density, 'se.fit' gives the standard error of the fit, 'Sample.Label' is an identifier for the cell, 'Grid.Area' is the area in km square of the grid cell, and 'geometry' is a Well Known Text representation of the cell polygon with coordinate reference system EPSG:3338. See the [GitHub site](https://github.com/USFWS/ACP-Mapping) for more information. This product was produced from the file write_map.R and objects within. Embedded within the database as the layer "Version" is a data table that contains the GitHub commit information identifying the code version used to create this product.