As harmful algal blooms (HABs) increase in magnitude and duration worldwide, they are becoming an expanding threat to marine wildlife. Over the past decade, domoic acid (DA) and saxitoxin (STX) have been increasingly problematic bicoastally in the United States. We investigated pooled seabird mortality data from opportunistic sampling events between 2007-2018, across three states, to examine the patterns and role of DA and STX in seabird mortality events from the continental United States. Patterns in DA and STX levels and affected tissue type were reviewed, and two specific accounts of localized and pervasive event types were examined. There has been increased toxin detection with expanded tissue testing during large mortality events. Additionally, there is new evidence of metabolic processing of HAB toxins in seabirds, and the first known account of coincident HAB intoxication (DA and STX) in seabirds is documented. This report contributes qualitative insight into temporal trends and provides recommendations for future research.