When large rivers discharge their water into the sea, this creates a plume of freshwater that is highly variable. A new study that attached tiny satellite tags to seabirds now shows that both shearwaters and murres prefer to forage in plumes created by the massive Columbia River. In particular, they prefer the boundary areas between freshwater and sea water, since this area is where zooplankton and prey fish species are most concentrated. The seabirds shift where they forage as the plume area expands and contracts in size, and moves north and south of the mouth of the Columbia River. The new paper by SAFS PhD student Elizabeth Phillips, SAFS professor John Horne, and their coauthors, appears in Marine Ecology Progress Series.