ARTICLES ON HAWAIIAN
BIRDS AND BIRDWATCHING AND OTHER
The Hawaiian Monk Seal (Monachus schaninslandi)
The Hawaiian Monk Seal (Monachus schaninslandi) is the most endangered Seal species in the United States with an estimated 1,300 remaining. It is one of only two extant Monk Seal species - the Mediterranean Monk Seal is found only in the Mediterranean Sea and adjacent North African Coast and numbers less than 500 individuals and the Caribbean Monk Seal has not been seen since 1952, and is presumed extinct. It is classed as an ENDANGERED species. The Hawaiian name for the Monk Seal is 'Ilio holo kai which means "the Dog that runs in the sea". The Hawaiian monk seal was officially designated endangered November 23, 1976 and is protected by the Endangered Species Act and the Marine Mammal Protection Act.
Between 1958 and 1996, mean beach counts of the main reproductive populations declined by 60%. Current population estimates range from 1300-1400 animals and the population continues to decline; from 1985 to 1996 the rate of decline was about 4% per year. While different island subpopulations exist, they are all managed as a single stock by the US National Marine Fisheries Service (NMFS).
"The three species of monk seal are part of the family Phocidae. Monachus is the genus, and it contains
the most primitive of all seals. Monk seal ancestors originated in the North Atlantic Ocean at a very early date.
The Hawaiian monk seal became separated from the Atlantic-Caribbean members of the genus as early as 15 million
years ago. The Hawaiian Monk Seal probably got its common name from the fact that it lives a monk-like or solitary
existence. Hawaiian monk seals are pinnipeds, which is the order of marine mammals including seals, sea lions and
walruses. There are believed to be about 34 different species of pinnipeds. All are characterized by having large
eyes, prominent snouts, streamlined shapes and four swimming flippers which typify the order. In fact, the word
pinniped means "feather-" or "fin-footed" in Latin. Although they have successfully adapted
to life in the sea, pinnipeds are thought to have evolved from terrestrial mammals about 20 million years ago and
continue to retain strong ties to land. Their closest modern day terrestrial ancestors are the bear and the dog.
Some biologists consider the pinnipeds to be so closely related to these species as to include them as members
of order carnivora which includes the dogs, bears, wolves, raccoons and others. Whichever classification scheme
you choose, the pinnipeds can be divided into three distinct families; 1) the Phocidae which are the "true,"
or earless seals 2) the Otariidae, the eared seals and sea lions, and 3) the Odobenidae, which includes only the
The three families differ mainly with respect to the possession of external ears and their means of locomotion. The Otariidae or eared seals, have external ears as their name implies. In addition, they have long front flippers that measure up to one-third of their body length which they use to propel themselves through the water. In the water, their hind flippers serve mainly as a rudder or as an aid in steering. On land, the hind flippers are able to turn under the seal's body and provide support, enabling them to make four-footed movements. Eared seals are fairly mobile on land as well as in the water. In contrast, the Phocidae, or true seals, lack external ears and hear through small holes on either side of their head. In the water, their hind flippers propel them when swimming while their front flippers act as rudders or stabilizers . On land, the hind flippers are not able to turn under the animal and provide support. This makes travel on land rather difficult for the true seals, reducing it to somewhat of a wiggle.
The walrus, lone member of the Odobenidae, seems to combine features of both the eared and the true seals. Walruses essentially lack external ears. At sea, they paddle mainly with their front flippers, similarly to eared seals, although their front flippers are not nearly as large, and their rear flippers move in lateral movements similar to true seals. On land, walruses are able to turn their rear flippers under their bodies for support, and make four-footed movements".
The Hawaiian monk seal is considered to be a Phocid, or true seal, meaning it has no external ears and swims by using its hind flippers for propulsion and its front flippers as stabilizers.
"In contrast to the Mediterranean monk seal, for which recorded history dates back more than 2,500 years, nothing is known of the Hawaiian monk seal in antiquity. Written reports began with the Russian explorer Lisianski, who in 1805 observed seals on the island that now bears his name. Records from voyages of the Aiona in 1824 and the Gambia in 1859 suggest that the species' distribution and abundance were reduced by unregulated seal hunts in the early to mid-1800s. The Gambia, for example, reportedly returned to Honolulu with 1,500 skins (although the authenticity of this report has been questioned). The seals were killed not only for pelts and oil; they were also killed for food by ship-wrecked sailors and by guano and feather hunters."
There are breeding populations at six islands in the North West Hawaiian Islands and occasionally Seals will pup on the Main Islands, most notably on Kaua'i and Ni'ihau. Monk Seals prefer sandy beaches and lava benches where they can haul themselves out of the water and rest and digest their food. Prey items which they like to feed on include bottom and reef fishes, lobsters and eels and most foraging occurs in water less than 90 meters deep, but has been recorded at a depth of 500m! Monk Seals are often faithful to their birth site and may return year upon year to give birth or feed and rest. Monk Seals are protected by law and should not be disturbed or approached within 100feet. Disturbance may cause a Seal to re-enter the sea before it is ready and may result in ill-health or even death.
"The Hawaiian Monk Seal grows to about seven or eight feet in length with females growing slightly longer than males. The adult female may weigh up to 600 pounds (range 400-600) and males weigh up to 400 pounds (range 300-400). New born pups weigh just 30 or 40 pounds. Monk Seals can live for as long as 30 years, although many only live 20 to 30 years.
Adults have a brownish pelage (coat); juvenile pelages are silvery gray on the back and sides and creamy white
on the belly, chest and throat; pup coats at birth are black and woolly, with fuzzy, short hair. Newborn pups display
a jet-black coat.
Monk seals are brownish when mature. They typically have scars both from sharks (such as tigers, gray reef and white-tips) and from being entangled in fishing gear. Mature females may also bear scars from aggressive males encountered during mating.
During the first molt (shedding of outer covering) after birth, the pelage hairs individually fall out. During successive annual molts, the epidermis peels off with the old hair to reveal the bright new pelage underneath. This epidermal molt is like the snake's shedding of skin. The only other seal known to molt like this is the elephant seal. The thickness of monk seal blubber is comparable to that of seals living in frigid climates. Monk seals keep cool on hot, windless days by lying on damp sand with light ventral pelage exposed at the water's edge and by making wallows into cool sand layers.
Monk seals normally don't stay on dry, hot, upper beach levels except during cool, windy or cloudy weather. Seals are also very inactive when ashore. Their respiration includes long periods of breath-holding, and the heart ratio that accompanies holding their breath is low. These behaviors result in low levels of metabolic heat production and are excellent natural adaptations to heat exposure. These disturbances may cause increased deaths among Hawaiian monk seal pups. Monk seals are solitary, both in the water and onshore. When loose groups form on beaches, they gather because the local environment conditions are favorable. Except for mothers with pups, resting seals avoid bodily contact with each other.
Monk seals vocalize from when they are young into adulthood. Pups utter "mwaa, mwaa, mwaa" and, when disturbed, an explosive "aaah" or "gaah". An alarmed adult sound consists of a "bubbling" that originates deep in the throat (with the mouth either open or closed). The bubbling resembles that of water from a jug.
Adult males constantly cruise along their favorite beaches in spring and summer, searching for receptive females. Monk seals give birth between mid-December and mid-August, with the peak breeding season occurring in May. The gestation period (from fertilization until birth) is about one year. Mothers usually give birth (called pupping) to small black fuzzy pups on sandy, coral beaches that are backed by shrubs; utilizing the shrubs for shelter during the night. Successful pupping also occurs on beaches where sheltering vegetation does not exist and, in recent years, pups have been born on rocky beaches. Apparently, however, when human activity forces pregnant females to desert their traditional pupping beaches to bear pups, pup survival is greatly reduced.
Mothers do not feed while nursing. Mothers nurse their pups for five to six weeks, and subsist entirely on energy stored in their blubber. A mother may lose up to half her body weight during the nursing period. At weaning, pups are enormously fat. Their weight has quadrupled since birth, to about 140 pounds. The body length, however, shows little change. After weaning, while the young seal learns to fend for itself, it steadily loses weight. At one year of age, juveniles weigh about 100 pounds.
Hawaiian monk seals are normally found on the leeward (southwest) sides of the northwestern Hawaiian islands, and occasionally sighted in the main Hawaiian islands. In June 1997, the first birth on Maui was recorded.
Monk seals feed on fishes and invertebrates both within atoll lagoons and in deeper water offshore. Common foods for monk seals are spiny lobster, eels (except conger and moray), flatfish, small reef fish, larval fish and octopus. Monk seals are also assumed to prey on pelagic (open ocean) species, but only because the monk seal is known to travel long distances in the open ocean. Monk seals may eat as much as ten percent of their body weight in a day. They sometimes spend many days at sea before returning to the islands where they sleep and digest their food.
Monk seal species have shown alarming population declines in recent years due to the rapid spread of human activity to even the most remote and isolated areas. Many monk seals were clubbed to death for meat, oil and their skin. In Hawaii, these factors have contributed to the seal's decline: death from predation by sharks lower pup survival as the result of human disturbances ciguartera intoxication entanglement in fishing nets and debris
Significant breeding areas for Hawaiian monk seals are mostly under the protection of the Hawaiian Islands National Wildlife Refuge, which is administered by the U.S. Fish and Wildlife Service."
Passages above in quotations from: © Copyright 1999 - 2001 Pacific Whale Foundation; and adapted from Marine Mammal Fact Sheet Series: Mediterranean Monk Seal © 1999 monachus.org, IMMA Inc.
In May-July 1997 there was a mass mortality of Mediterranean monk seals at the important colony on the Cap Blanc
Peninsula, Mauritania/Western Sahara, claiming the lives of over 70% of the population, mostly adults and sub-adults,
and reducing numbers at the colony from an estimated 310 to less than 90. There have been conflicting opinions
as to whether the cause of the mortality was a toxic "red tide" or a newly-found virus that was found
in some of the dead seals. This mass mortality could have a profound effect on the species' survival since the
Cap Blanc colony was the largest population of Mediterranean monk seals and the only one to possess the actual
social and numerical structure of a colony.
The Mediterranean monk seal is listed as critically endangered by the International Union for the Conservation of Nature and Natural Resources (IUCN). This species is also listed on Appendix I of the Convention on International Trade in Endangered Species (CITES). Extremely sensitive to human disturbance, today the Mediterranean monk seal numbers between 300- 500 animals."
Passages above in quotations from adapted from Marine Mammal Fact Sheet Series: Mediterranean
© 1999 monachus.org, IMMA Inc.
The Caribbean monk seal was formally declared extinct in the 1996 IUCN Red List of Threatened Animals. The last reported sighting in 1952 was from Seranilla Bank between Jamaica and Honduras, where a small colony was known to have lived. The Caribbean monk seal was documented as being easily approachable and not aggressive and they were easily killed during directed hunts in the 17th and 18th centuries. It is also known that sailors, whalers, and fishers opportunistically killed the seals they encountered. As well, Caribbean monk seals were killed by museum collectors and displayed in zoos. All monk seal species appear to be sensitive to disturbance, and early habitat exclusion by humans throughout their range may have exacerbated their decline. In response to recent unconfirmed Caribbean monk seal sightings in areas within their historical range, surveys have been carried out as late as 1993.
Very little scientific information was gathered before the Caribbean monk seal disappeared. Males are thought
to have reached a length of 2.1 to 2.4 m; females may have been slightly smaller. The backs of adult seals were
brown with a grey tinge; the underside was pale yellow, as was the muzzle. The fur of newborns was long and dark.
Evidence suggests that the pups were born in December weighing between 16 and 18 kg, and measuring up to 1 m in
Passages in quotations above from adapted passages from Marine Mammal Fact Sheet Series: Caribbean Monk Seal
© 1999 monachus.org, IMMA Inc.
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