Trophic ecology is a very important component of the overall ecological niche of populations and a central theme in their studies. As many other marine organisms, seabirds must cope with unpredictable and patchily distributed marine resources and they need to find food (most often mobile prey, such as fish) within their limited movements in the water column. Recently, modern techniques to study trophic ecology and diets of seabirds have become available, allowing enormous developments in their study. The temporal and spatial limitation of conventional methods have been surpassed. Here, an updated synthesis to guide the application of modern approaches, discussing the pros and cons of each method, and providing a case study focused on a small and elusive seabird group, the storm petrels has been provided. This review summarizes the most recent progress in the application of the most common and important techniques to date, including the stable isotope method, lipids as trophic markers and DNA metabarcoding and taking into consideration conventional diet analyses, a central technique in the study of seabird populations. No method is free of bias, and a complementary approach using at least two different methods could be chosen appropriately to correctly identify and quantify diet items is advisable.