elephant seal tag-resight

Northern elephant seals recolonized central California in the 1950s and 1960s after being extirpated by hunters during the 19th century. Pupping began at Año Nuevo Island in 1961 and expanded to the adjacent mainland in 1975. Since 1967, researchers from the University of California, Santa Cruz, and the Smithsonian Institution have been placing numbered cattle ear tags in the flippers of pups born at Año Nuevo, allowing tracking of individuals over many years. Sightings of tagged individuals produce estimates of lifespan, movements between beaches and rookeries, and models of population growth. From 1967-2007, 16609 pups were tagged at Año Nuevo, and 1559 of these have been resighted. The oldest animal observed was a 21-years old female (born in 1984 and seen raising a pup in 2005), and two different females have been seen in 14 different years (both were still alive as of mid-2007). The main goal of the tag-resight project is to document survival and dispersal during the current population growth phase, to provide a baseline against which to compare future demography, after the population stabilizes or declines. It is part of a broader research effort covering many aspects of breeding behavior, physiology, foraging, and migration of elephant seals