Harbor Seals

Identification of pups from aerial photographs is a challenge for estimating productivity of harbor seal populations, partly due to the presence of yearlings, which are similar to pups in size and appearance. To distinguish harbor seal pups from yearlings, researchers typically rely on visual assessments of relative size, proximity, and orientation to nearest neighbors, as well as pelage color. Since most of these criteria are spatial in nature, we used a GIS to quantify our identifications of pups in aerial photographs from biweekly surveys.