The Harbor seal does not migrate with the seasons. West Coast, San Franciso Bay has the resourses to support a year-round resident population which lives, feeds, and pups within the Bay's waters.
Seals take advantage of the warmer daylight hours to come ahore. The relatively warm air temperures on lond allow icreased blood flow to the skin, speeding healing of cuts and wounds, and nourishing hair growth during the seals' annual summer molt. Oh yeah, all seals have a multi-dimernsional layer of fat, called blubber. This keeps them warm in the cold weather. So they can stay in the ice waters or in snow for a longer period of time then most animals.
Harbor seals use a variety of "haul-out" sites for resting or pupping. A haul-out site is a shoreline region where seals congrete, primarliy to rest or to nurse their pups. Haul-out sites may be mudflats, sandflats, rocky outcoppings exposed only at low tide, or marshland covered with wetland vegetation, but they all share two key characteristics: isoltaion from predators or human and easy access to water.
Up to 40 percent of San Franciso Bay's resident seals devlop red-colored fun on their head, shoulders, or entire body. MAay of these "redcoat" seals, often those with the deepest red color, develop abnormally short vibrissae (whiskers). Vibrizzae are sensory organs used in feeding; they guide seals to fod by detecting the waves created by passing fish. In studies of captive seals, shortened vibrissae made it harder for seals to catch fish. The potential link between the redcoat phemeono and contaminants is currently under study.
Studies since 1986 have indicated a host of harmful effects on health of harbor seals living in the Wadden Sea, north of the Nertherlands. The Wadden Sea is polluted by Rhine River discharge containing a variety of toxic contaminants, including PCBs, dioxins, and furans. The effect of toxic pollution on harbor seal health is a primary focus of the Seal Project.
Harber seals insulating blubber renders harbor seals less prone to hyppothermia sshould oil coat their fur, but, like all mammals, they are susceptible to the toxic effects of ingesting oil while feeding. Pups nursing from oil-coated mother's body are subject to amplified risk due to ingestion of oil on the mother's body. Seals also suffer the toxic effects of oil spills by inhaling the fumes from slicks.