| Emergenceof adult aquatic insectsdepends on watertemperatureand its timing influences thisephemeralbut often criticalresource for terrestrial insectivores. Spatial heterogeneity in timing of emergence and itsconsequences forterrestrial insectivores are poorly understood.We investigatedthe emergence phenology of the giant salmonfly (Pteronarcys californica)at three different scales in two Idaho river networks, and we studied the influence of tributary confluences on this timing, along with associated birdresponses. At the basin-scale,salmonfly emergence timing was patchy, whereas at the scale of a sub-drainage,emergence followed a downstream-to-upstream pattern. At the scaleof reachesthermal discontinuities created by tributary confluencescreated asynchrony in salmonflyemergence. Many bird species consumed salmonflies andsome captured large numbers of them. Emergence asynchrony created by tributarieswas associated with shiftsin bird abundance and distributionas they apparently tracked the availability of this pulsed prey resource.Key Wordsstreaminvertebrate, food webs, Pteronarcys, salmonfly, birds, tributary confluences, resource subsidies, resource waves |