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This paper reports on sightings and dispersion of individual southern elephant seals (Mirounga leonina) along the Atlantic and Pacific coasts of South America based on reports of tagged/marked seals from Patagonia and of animals of unknown origin. From 154 sightings, encompassing at least 354 individuals, we found that individuals dispersed to subequatorial latitudes on both sides of the continent, and to more temperate sites, in the Magellanic region of Tierra del Fuego. Nineteen sites were visited by tagged seals from the established colony of Peninsula Valdés (PV, Argentina). PV and the smaller seal population of the Falklands/Malvinas were regularly connected by adults of both sexes. There were more sightings of males than females. No incipient new breeding colonies were found along the Atlantic coast of South America. Some observations coincided with places where elephant seals had been recorded or exploited in the seventeenth and eighteenth centuries. A shortage of suitable habitat for expansion and proximity to predictable food could act as a stabilizing process preventing colonization of new areas from PV. Dispersion data, coherent with population genetics, support a Patagonian elephant seal stock. [ABSTRACT FROM AUTHOR]

The study describes the annual cycle of southern elephant seals for the increasing colony of Peninsula Valdés, and compares it to the haul-out pattern reported for stable or decreasing sub-Antarctic colonies of the species. Data were collected during censuses of the entire colony (nine breeding seasons, two moulting seasons and one autumn--winter haul-out), monthly surveys of coastline and mark-recapture of pups. Pup production during the study period grew from 12 113 to 14 621 animals (1995-2003). Most relevant events of the cycle were similar for all colonies studied, independent of the geographical location, size or population trend. Compared with other locations where southern elephant seals breed and moult, distinct features for Peninsula Valdés were: i) breeding occurs earlier in the spring, and ii) most adult females reproduce and moult in the same colony. The increasing number of animals ashore was correlated with the expansion in pup production. Population trends and stability of demographic events could be related to a consistent physical environment (ocean fronts) during foraging phases of the annual cycle. [ABSTRACT FROM AUTHOR]