Sauer studies the Common Loon and migratory songbirds as wildlife indicator species to assess the effects of mercury deposition on Adirondack ecosystems. She has also designed and implemented studies to evaluate mercury bioaccumulation in Adirondack food webs, including conducting laboratory analysis of songbird tissues, soils, and invertebrate samples to determine their mercury concentrations. 

Her doctoral research focuses on the transfer of mercury through terrestrial food webs to songbird communities inhabiting northern hardwood forests, montane boreal forests, and Sphagnum bog habitats in the Adirondack Park. In addition to field work, she gives public and scientific presentations; prepares reports, publications, and newsletters; and develops and presents school curricula.