During the months of February, March, and April, 2004, a haul-out site was observed on Prudence Island, RI, for harbor seal (Phoca vitulina) behavior with emphasis on nocturnal activity. Results showed an average of 22 seals hauled out during the day, with an average of 16 per night. The relationship between temperature and seal number was weak, r2 = 0.06, yet a slight trend revealed that seal numbers dropped as temperature increased. Wind speed had little effect with r2 = 0.02. Scanning behavior was divided into constant and semi-constant scanners with a ratio of 2–4 scanner seals in groups of 10–40, and individual scanners in groups of less than 7, for both day and night observations.