True Seals: Phocidae

Physical characteristics: Adult Hawaiian monk seals have short, silvery gray coats, which turn lighter on their undersides. As a seal ages, its coat turns a deep brown with each molt. Females, at about 7.5 feet (2.3 meters) and 528 pounds (270 kilograms), are larger than males. Males measure about 6.9 feet (2.1 meters) long and weigh 385 pounds (175 kilograms).

Geographic range: Hawaiian monk seals are found in the United States.

Habitat: Hawaiian monk seals inhabit the Pacific Ocean waters surrounding the northwestern Hawaiian islands. They breed, rest, and molt on coral reef islands. A small number are found on the main

Hawaiian monk seals live in the Pacific Ocean waters surrounding the northwestern Hawaiian islands. They breed, rest, and molt on coral reef islands. (© Frans Lanting/Photo Researchers, Inc. Reproduced by permission.)

Hawaiian Islands. Cows choose breeding areas with a coral shelf that affords protection from the sun and sharks.

Diet: Hawaiian monk seals feed on deep-water fish and other fish found in the coral reefs. They also eat squid, octopuses, and lobsters.

Behavior and reproduction: Hawaiian monk seals are solitary, living alone, except during the breeding season. Females give birth to a single pup that they nurse for four to six weeks. A cow sometimes nurses another cow's pup. Females mate soon after they leave their pups, typically in the water. Bulls are believed to have several partners. In areas where males outnumber females, mobbing occurs, in which a group of adult males attempt to mate at once with an adult or an immature female, sometimes fatally injuring that individual.

These seals are active at night, sleeping during the heat of day. They do not migrate, but may spend many days foraging at sea before going ashore to sleep. They do not tolerant humans. When disturbed, they either do not go ashore to breed or give birth in a less preferred site. Pups usually do not survive under these conditions.

Hawaiian monk seals and people: Hawaiian monk seals have recently inhabited the main Hawaiian islands. Since they are listed as Endangered and, therefore, legally protected, their appearance on tourist beaches has prompted restrictions or closure that may turn people against them.

Conservation status: The U.S. Fish and Wildlife Service and IUCN lists the Hawaiian monk seal as Endangered due to habitat loss to human expansion, lack of young females for mating, male mobbing of females, reduced prey, and entanglement in ocean debris and commercial fishing gear. ∎