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Hawaiian Monk Seal

Monachus schauinslandi
Hawaiian monk seal

Adults are silvery-grey colored backs with lighter creamy coloration on their underside. The back of the animals may become darker with age, especially in males. Adult females are generally larger than males.

Seals undergo a complete molt each year, typically between April and December. The seals shed all of their hair and a layer of skin within approximately 7-10 days and usually remain on shore the majority of the time.

Females typically mature between 5-6 years of age and it is unknown when males mature. Males bite the back of females while mating and can rip skin and blubber. Mating takes place in the water and females tend not to give birth on beaches where there is much human activity. The gestation period is 10-11 months. Births can occur during any month, but most pups are born between late March and early April, but birthing has been recorded year round. Females nurse their pups for approximately 5-6 weeks. Seal milk is very rich which allows pups to gain weight rapidly with pups more than quadrupling their initial weight before weaning. The mother seal loses a tremendous amount of weight while nursing.

The Hawaiian monk seal is one of the rarest marine mammals in the world. Part of the "true seal" family, they are one of only two remaining monk seal species. The other is the Mediterranean monk seal, and a third monk seal species, the Caribbean monk seal, is extinct.

Endemic to the Hawaiian archipelago and found mostly in the Northwestern Hawaiian Islands, although sightings reported from main Hawaiian Islands are increasing. Less than 1,200 seals are scattered throughout the entire archipelago. About 60 individuals reside at Midway Atoll. Most seals remain at their birth atoll for life, but there is some inter-atoll movement. 

Primary natural factors affecting monk seal recovery include predation by sharks, aggression by adult male monk seals, reduction of habitat and prey associated with environmental change. Entanglement in marine debris such as fishing nets and lines, and plastic rings are other sources of mortality.

Monk seals haul out to rest or sleep, pup, and molt and should not be disturbed. If you see a seal on the beach, do not approach closer than 50 m (150 ft). Increase distance if seal is aware of you.

Facts About Hawaiian Monk Seal

Diet
Reef fish, squid, octopus, and crustaceans
Life Span
25-30 years
Size
Adult body length: 2.1-2.3 m (7-7.5 ft); weight: 170-205 kg (375-450 lbs). Pups are jet black, weigh 16 kg (35 lbs), and are 1 m (3 ft) at birth.
Page Photo Credits — USFWS
Last Updated: Sep 11, 2013
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