Reproductive Behavior and Life History
Reproductively mature male sea lions aggregate in May on traditional, well-defined reproductive rookeries, usually on beaches on isolated islands. The larger, older males establish and defend distinct territories on the rookery. A week or so later, adult females arrive, accompanied occasionally by sexually immature offspring, and form fluid aggregations throughout the rookery. Like all other otariids, Steller sea lions are polygynous. However, unlike some other species, they do not coerce individual females into harems but control spatial territories among which females freely move about. Steller sea lions have used three types of territories; aquatic, semiaquatic and terrestrial. Males with semiaquatic territories have the most success in defending them. The boundaries of territories are defined by natural features, such as rocks, faults or ridges in rocks. Territories can remain stable for 60 days.
Pregnant females give birth soon after arriving on a rookery, and copulation generally occurs one to two weeks after giving birth, but the fertilized egg does not become implanted in the uterus until the fall. Twins are rare. After a week or so of nursing without leaving the rookery, females begin to take progressively longer and more frequent foraging trips, leaving their pups behind, until at some point in late summer the mother and pup both leave the rookery. Reproductive males fast throughout the reproductive season, often without entering the water once from mid-May until August, at which point the structure of the reproductive rookeries begins to fall apart and most animals leave for the open seas and disperse throughout their range.
The age at weaning is highly variable; pups may remain with their mothers for as long as four years. Incidents of mothers feeding daughters who are simultaneously feeding their own newborn pups have been documented, an extremely rare occurrence among mammals.
Read more about this topic: Steller Sea Lion
Famous quotes containing the words reproductive, behavior, life and/or history:
“In the nineteenth century ... explanations of who and what women were focused primarily on reproductive events—marriage, children, the empty nest, menopause. You could explain what was happening in a woman’s life, it was believed, if you knew where she was in this reproductive cycle.”
—Grace Baruch (20th century)
“No one is without Christianity, if we agree on what we mean by that word. It is every individual’s individual code of behavior by means of which he makes himself a better human being than his nature wants to be, if he followed his nature only. Whatever its symbol—cross or crescent or whatever—that symbol is man’s reminder of his duty inside the human race.”
—William Faulkner (1897–1962)
“There is nothing so noble and so right as to play our human life well and fitly, nor anything so difficult to learn as how to live this life well and according to Nature.”
—Michel de Montaigne (1533–1592)
“The history of the world is the record of the weakness, frailty and death of public opinion.”
—Samuel Butler (1835–1902)