How to Identify Seal in Maine

Harbor Seals are smaller, typically 4.5 to 6 feet long, with a rounded head and a dog-like face. They have a mottled brown, tan, or grey coat with scattered dark spots or rings. Their nostrils point downward in a V-shape. Grey Seals are significantly larger, reaching 7 to 9 feet in length, with a longer, more rectangular head and a more prominent snout. They are usually darker, ranging from grey to brown to nearly black, often with fewer markings than harbor seals. Their nostrils are farther apart and point more forward. If you see a large, dark seal with a long face, it is likely a Grey Seal; a smaller, spotted seal with a rounder head is almost certainly a Harbor Seal.

Harp Seals are rare in Maine and appear only during winter months, typically December through March. They are medium-sized, averaging 5.5 to 6.5 feet long, with a silvery-grey or yellowish coat. Newborns and juveniles often show a distinctive dark face mask, and older animals may display a harp-shaped dark marking on their back, which gives the species its name. Most sightings in Maine are of younger animals that have drifted south from Arctic breeding grounds. If you see a seal in Maine between April and November, it is not a Harp Seal.

Harbor Seals are curious and often haul out on rocks and ledges in small groups. They bob vertically in the water with just their head and sometimes shoulders visible, a posture called 'bottling.' They are generally cautious and will slip into the water if approached on land. Grey Seals are more robust swimmers and often remain in the water longer. Harp Seals, when present, tend to stay near ice or in deeper offshore waters and are less commonly spotted from shore. If you see a seal hauled out on a Maine coastal rock during summer, it is almost certainly a Harbor Seal.

On land, look at the overall size and proportions first. Harbor Seals have a compact body, small flippers positioned somewhat forward, and a short neck. Their movements on rocks are undulating, similar to an inchworm. Grey Seals have longer flippers positioned further back on their body, giving them a more powerful appearance on shore. They can rotate their rear flippers forward, which Harbor Seals cannot do easily. Harp Seals, if seen, would show that distinctive face mask or back marking. Coloring alone is not reliable for identification, as both harbor and grey seal coats vary widely.

Harbor Seals are relatively quiet on land but make distinctive underwater vocalizations including chirps, clicks, and bell-like tones. Grey Seals produce deeper, more powerful underwater sounds and are generally louder. Both species can be heard while diving or hunting underwater if you are quiet and listening from a vantage point near the water. Harp Seals produce a repertoire of grunts, knocks, and roars, though these are most commonly heard in their Arctic breeding colonies rather than in Maine waters. Sound identification requires practice and usually works best when combined with visual observation.

Harbor Seal heads are rounded and often described as 'dog-like,' with a relatively short muzzle and a gentle slope from the forehead to the nose. The eyes are large and positioned on the sides of the head. Grey Seal heads are distinctly more elongated, with a longer, flatter profile and a more prominent snout that protrudes further forward. This is one of the most reliable ways to distinguish the two species from the side view. Practice noticing the profile when viewing photographs or field guides, as this single feature will help you identify most seals you encounter.

Harbor Seals haul out on exposed rocks, ledges, and small islands throughout Maine's coast, from Casco Bay north to the Canadian border. They favor areas with rocky substrate and access to fish-rich waters. Grey Seals prefer more exposed offshore rocks and islands and can be found in the same general regions but less frequently close to shore. Peak season for harbor seals is June through August, when sightings exceed 450 observations per month. Grey seals are present year-round but are least common during winter. Harp seals, if encountered, are confined to deepwater areas and are extremely rare.

Yes, whisker patterns and nose markings are unique to each seal, much like human fingerprints. Researchers use these features to identify and track individual seals over time. The pattern of darker pigmentation around the nose and the arrangement of whiskers are distinctive and stable throughout an animal's life. While this level of detail requires close observation and experience, amateur naturalists can use these patterns to recognize the same seal if encountered multiple times at the same haul-out site. This practice deepens your connection to local seal populations and contributes to community science when recorded and shared with iNaturalist.

Harbor Seals have short, dense fur that lies flat against their body and repels water effectively. The fur appears smooth and can show clear spotting or mottling patterns. Grey Seals have coarser, somewhat longer fur that also lies flat but often appears less sleek than harbor seal fur. Both species have a thick layer of blubber beneath the fur, which is what keeps them warm in cold Maine waters. The differences in coat texture are subtle and best observed when the seal is hauled out and dry. Juvenile seals of both species are often lighter in color than adults.