This project investigated the social ecology and baseline behavior of long-finned pilot whales as part of a broad multi-investigator research program that seeks to understand how cetaceans are affected by mid-frequency sonar and other sources of anthropogenic noise. The study of how noise affects large delphinids is important since results so far have suggested that they have different responses to anthropogenic noise sources compared to beaked whales. However, studies have been hindered by high inherent variability in acoustic and diving behavior and a lack of understanding of the underlying factors shaping this variation. Our goal is to develop new field and analytical methods for studying the baseline behavior and effects of noise on group-living cetaceans, where social responses to noise such as changes in group cohesion likely constitute important predictors of disturbance. We aim to gather data to design, conduct and interpret controlled exposure experiments to social delphinids such as pilot whales, with the ultimate goal of understanding responses to naval sonar and improving Navy environmental analyses.