There are variations in coat color in harbor seals. Coat color can range from nearly white with dark spots, to black or dark brown with white rings. This red coloration of the coat results from iron oxide precipitates deposited on the hair. Allen et al.
Harbor seals are highly opportunistic feeders.
Their diet reflects regional and seasonal variations in prey availability, and include a variety of fishes, cephalopods, mollusks and crustaceans. Seals haul out for a number of reasons, including resting, thermoregulating, giving birth, nursing, molting, and facilitating digestion. Haul out sites are generally characterized by environmental features such as easy access to the water, low profile substrate, low human disturbance, and proximity to abundant prey sources. Diurnal cycles, tide state and height, and disturbance levels all appear to play a role in the number of seals present on the haul out. While some haul outs are used mainly for resting, certain haul outs are important rookeries for harbor seals.