Despite the fact that harp seals are considered a northern species, dependent upon pack ice habitats for pupping, sightings of juveniles in the southern Gulf of Maine have increased in the last decade, during the winter months. Sightings of adults are less common but increasing. . When inflated, it forms a black, oval hood. Further, they can inflate the red, inner lining of the nose out of one nostril. This spectacular display may be used to reduce actual fighting during conflicts with other seals.
Adults are silvery blue or white with irregular dark brown patches.
In this area, hooded seals are a rare sight. Young are nursed for a mere four days and may double their birth weight by weaning. Most sightings locally are of the young of the year. Males and females differ little and their mass changes radically throughout the year, especially during the molt when animals are unable to feed. They are generally dark gray above and cream below with a constellation of light rings scattered across the head and back.