DIETARY ECOLOGY OF SEABIRDS: A CRITICAL REVIEW OF PATTERNS OF PREY USE, METHODOLOGICAL ADVANCES, AND RESPONSES TO ENVIRONMENTAL CHANGE

euphausiid krill to forage fish, mesopelagic fishes, cephalopods, crustaceans, carrion and, in some generalist species, terrestrial or anthropogenic food. Their diets are shaped by prey availability, body size, feeding morphology, diving capacity, habitat, season, breeding constraints and interactions with fisheries. This review synthesizes literature on seabird diet, emphasizing prey composition, dietary specialization and flexibility, spatial and temporal variation, methods of diet determination, and implications of dietary change for conservation. A systematic thematic approach was adapted from the methodology used in the accompanying methodological review, with recent literature emphasized for 2020-2025 and older studies retained when they established foundational methods, global patterns or long-term ecological context. The evidence indicates that no single seabird diet is representative of the group: penguins and several Procellariiformes may rely strongly on krill, myctophids, fish or squid; auks often target energy-rich forage fish and zooplankton; gannets, cormorants and many terns are predominantly piscivorous; whereas gulls and skuas display greater trophic plasticity and frequently incorporate carrion, discards and terrestrial resources. Conventional stomach, pellet and regurgitate analyses provide direct taxonomic information but are affected by digestion and sampling biases. Stable isotopes and fatty acids extend inference to assimilated diet and trophic niche, while DNA metabarcoding can substantially improve prey identification, although quantitative interpretation remains constrained by DNA degradation, primer bias and reference-database limitations. Collectively, the literature supports a complementary, multi-method approach to seabird diet research and demonstrates that diet is both an ecological trait and a sensitive indicator of marine ecosystem change.