The primary objectives for this contract are to continue supporting ongoing contributions to the regions knowledge on the impacts of avian predation on juvenile salmonids in the Columbia River basin (CRB) by: (1) assessing the distribution and size of piscivorous waterbird colonies and (2) determining the colony-specific and cumulative, system-wide impacts of colonial waterbirds on juvenile salmonid survival in the CRB. As part of these objectives we will (a) locate and estimate colony size (with cost sharing, as appropriate and available) at all piscivorous waterbird colonies within foraging range of juvenile salmonids in CRB, including information on any new or incipient colonies; (b) estimate colony-specific predation rates (with cost sharing, as available and appropriate of piscivorous waterbirds; (c) measure reach-specific and cumulative predation impacts by multiple avian predator species and survival rates of multiple salmonid ESUs/DPSs; (d) estimate the additive effects of avian predation on smolt survival and smolt-to-adult survival; and (e) investigate the biotic and abiotic factors that influence smolt susceptibility to avian predation, with a focus on management-relevant factors.