The Arctic Coastal Plain (ACP) in northern Alaska provides denning habitat for polar bears and has several oil and gas fields currently in development or extraction phases (the National Petroleum Reserve, Alaska). To assure that wintertime exploration and development activities do not disrupt denning or threaten survival of cubs, managers need to know the distribution of the landscape features where polar bears are most likely to dig maternal dens. Maps of potential den habitat were developed for the central and eastern portions of the ACP using standard photogrammatic techniques. The map below was developed using a fine-grain digital elevation model, derived from Interferometric Synthetic Aperture Radar (IfSAR). It shows snow-catching landscape features suitable for polar bear denning within the petroleum reserve. The final map identified 82 percent of actual den habitat estimated to be within the reserve. Mapping denning habitat with IfSAR data compared favorably with the photogrammetric methods used for other regions of the ACP. Photogrammetric methods are labor-intensive and results depend on subjective interpretation, whereas mapping with IfSAR relies on objective criteria, has greater flexibility, requires less manual labor, and IfSAR data can be interrogated quickly and consistently with standard GIS tools. Using IfSAR data to identify polar bear maternal denning habitats is a useful management tool in the National Petroleum Reserve.
Example of IfSAR data in the National Petroleum Reserve – Alaska
with hillshading to increase the visibility of terrain changes. Abrupt changes in landscape are indicated by extreme dark or extreme light shading. Potential polar bear den habitat
identified with black lines highlighted with a white border, occurred mostly along stream banks and lakeshores.