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:
“The blind conviction that we have to do something about other people’s reproductive behaviour, and that we may have to do it whether they like it or not, derives from the assumption that the world belongs to us, who have so expertly depleted its resources, rather than to them, who have not.”
—Germaine Greer (b. 1939)
“In abnormal times like our own, when institutions are changing rapidly in several directions at once and the traditional framework of society has broken down, it becomes more and more difficult to measure any type of behavior against any other.”
—John Dos Passos (1896–1970)
“One idea is enough to organize a life and project it
Into unusual but viable forms, but many ideas merely
Lead one thither into a morass of their own good intentions.”
—John Ashbery (b. 1927)
“It may be well to remember that the highest level of moral aspiration recorded in history was reached by a few ancient Jews—Micah, Isaiah, and the rest—who took no count whatever of what might not happen to them after death. It is not obvious to me why the same point should not by and by be reached by the Gentiles.”
—Thomas Henry Huxley (1825–95)