Walrus Facts and Walrus Information
1. Distribution - Walruses are circumpolar, but they are concentrated in several geographically separated areas, with little or no chance of interbreeding.
* Pacific walruses inhabit the Bering, Chukchi, and Laptev seas.
* Atlantic walruses inhabit coastal areas of north eastern Canada and Greenland.
* Walruses are generally found where the water is not more than about 80 m (262 ft.) deep. They prefer a habitat with a gravelly bottom.
2. Migration - The walruses' migration follows the extent of the pack ice. Throughout the year, they occur primarily in or near the southern periphery of the pack ice.
* Pacific walruses winter in the central and south Bering Sea and summer in the Chukchi Sea.
* Migration of the Canadian population is less well-known. They seem to remain in the same general vicinity all year.
* Walruses migrate primarily by swimming, but they may also ride ice floes. Some of them may migrate more than 3,000 km (1,863 mi.) each year.
3. Physical Characteristics - Walruses are characterized by their large size, and by their tusks and numerous vibrissae. The Pacific walrus is slightly larger than the Atlantic walrus.
* Male Pacific walruses weigh about 800 to 1,700 kg (1,764-3,748 lb.) and are about 2.7 to 3.6 m (9-12 ft.) long. Female Pacific walruses weigh about 400 to 1,250 kg (882-2,756 lb.) and are about 2.3 to 3.1 m (7.5-10 ft.) long.
* Atlantic walruses are slightly smaller: males weigh about 908 kg (2,000 lb.) and reach lengths of 2.9 m (9.5 ft.). Females weigh about 794 kg (1,750 lb.) and reach lengths of 2.4 m (8 ft.).
4. Behavior
A. Social structure.
* Walruses are among the most gregarious of animals. They exhibit social behavior all year and congregate by the hundreds. Walruses haul out in herds; they seldom haul out alone.
* Males and females form separate herds.
* Social dominance is well established in herds and subgroups. Dominance within herds is established by tusk size, body size, and aggressiveness. The largest walruses with the longest tusks are the most aggressive and threatening. Animals that are smaller or those with small or broken tusks have a lower social ranking.
B. Social behavior.
* The role of tusks is primarily social. Walruses use them in dominance displays, and they are only secondarily used as weapons.
* A male will fight if another male intrudes upon him during a courtship display. These fights often result in physical injury. The frequent scars and lacerations seen on the necks and shoulders of adult males after the breeding season are evidence of tusking.
* Individuals frequently compete for the most favorable haul-out sites.
* Vocalizations are an important part of a male's courtship display for females
* Adult walruses occasionally trample walrus calves, but this is generally acciden
tal rather than aggressive behavior.
5. Food preferences and resources
* Walruses prefer molluscs, mainly bivalves such as clams. They suck bivalve animals from the shells. Walruses also eat many other kinds of benthic invertebrates including worms, gastropods, cephalopods, crustaceans, sea cucumbers, and other soft-bodied animals. Walruses may occasionally prey on fishes such as polar cod.
* Walruses may eat the remains of young seals when food is scarce.
* There are some rare but habitual seal-eating walruses. Their diet consists mainly of ringed and bearded seals. These are usually male walruses, recognizable because they are usually larger than other males with powerful shoulder and chest muscles. Their skin may become grease-stained from the blubber of the seals.
6. Reproduction - Most male walruses are sexually mature at about eight to ten years. Successful reproduction, however, probably doesn't occur until 15 years of age, when the male attains full physical growth and is able to compete for females. Most females are sexually mature at about five to six years. Successful reproduction probably begins at about ten years.
* Only a portion of the female population mates each year, as some are pregnant from the year before. Nonpregnant females may go into estrus some time between December and June, and most ovulate in February.
* In the Pacific, female herds meet male herds as they move south into the central and south Bering Sea in January. Estrous females gather at traditional places separate from pregnant females.
* Most mating probably occurs from December through March, when most sexually mature males produce viable sperm. Mating takes place off the pack ice, remote from shore; breeding locations are thus largely inaccessible for observation.
* Each herd of estrous females is attended to by one or more large adult males. According to one study, the ratio of males to females averaged 1 to 23.
* The males display visually and vocally from the water while the females rest. A display occurs both at and below the surface and lasts about two to three minutes. It includes teeth-clacking, clanging bell-like sounds, and whistles.
* Bulls either maintain a distance of about 7 to 10 m (23-33 ft.) or fight violently with each other.
* When displaying males are present, subadult males are scarce or absent. Those present remain on the fringes of the group and do not display.
* Females leave the ice to join a male in the water, where copulation takes place.
* After the mating season, mature bulls return to all-male herds.
7. Birth and Care of Young - Total gestation is 15 to 16 months. Gestation includes a period of delayed implantation: when the fertilized egg divides into a hollow ball of cells one layer thick (blastocyst), it stops growing and remains free-floating in the uterus for four to five months. The blastocyst then implants on the uterine wall and continues to develop. Delayed implantation ensures that the calf will be born when environmental conditions are optimal for its survival.
* Calves are born mid-April to mid-June, on the northward migration. They are usually born on the ice.
* Newborn calves weigh about 45 to 75 kg (99-165 lb.) and are about 95 to 123 cm (3-4 ft.) long.
* Calves are ashen gray to brown with dense, short soft fur. About two to three months before birth, the calf sheds a fine white layer of soft fetal hair called the lanugo.
* Within days or weeks, the calf becomes more robust. Its fur turns reddish-brown to tawny within one to two weeks. Calves shed and replace their natal coat when they are one or two months old. This first molt is usually completed by August. Calves then molt annually.
* By one month of age, calves are strong swimmers.
* A pregnant, near-term cow and her calf from the previous pregnancy usually separate in late April, just before the new calf is born. Mother and calf stay together two years or longer if the mother doesn't produce another calf. Young males may stay an additional two or three years before joining an all-male herd. Females tend to stay with the same herd.
More info: Did you know?
That the walrus has air sacs under their throats that they can fill like floatation bubbles and bob vertically in the water and sleep!
* That a walrus can move on land as fast as a man can run! Unlike seals, who have to drag their hind ends around, a walrus can walk on all fours!
* That the walrus has a special strategy to dig for clams -- the SQUIRT! A walrus squirts high-power jets of water out of their mouths! They use this talent like a water drill to get to clams under the mud!
* That the walrus has the best creature mustache! With as many as 700 hairs packed on their snout, a walrus has a nose for sniffing out food and nuzzle-kissing their friends! They love to sunbathe, and in the cold waters they swim in -- sometimes diving as deep as 300 feet -- a little sun must be nice and warm! Usually timid and shy, but easily provoked, the walrus has two massive tusks which it uses in three ways: to get girls, to get a grip when climbing out of the water onto ice, and to anchor themselves on the ocean bottom while digging for clams.
* That the biggest tusked bull has breeding rights.
* That the walrus dines on clams, snails, mussels, and 40 other kinds of invertebrates all found at the bottom of the sea. Walruses communicate to each other with knocks, bells, clacks, and whistles, and love to hang out in big piles on the beach of more than 100!
