The Arctic is warming nearly four times as rapidly as other regions of the planet, challenging the capacity of organisms to cope with shifting resources and maintain thermal balance. Tracking responses of free-living animals in dynamic environments can be challenging, but is increasingly enabled by advanced biologging approaches. We used data gathered from miniaturized bird-borne devices to demonstrate increases in energy expenditure with declining sea ice conditions and warming sea surface temperatures in a dove-sized seabird, the little auk (also named dovekie; Alle alle). This keystone species feeds on sea ice-associated copepods and inhabits large breeding colonies in the High Arctic.