The colony of southern elephant seals ( Mirounga leonina ) at Península Valdés (Argentina) grew by 0.9% from 2000 to 2022, reaching a population of 18,000 reproductive females. In 2023, an epidemic of the High Pathogenicity Avian Influenza H5N1 virus led to the death of almost all pups and an unknown number of adults. We tested five scenarios that included complete pup mortality along with varying levels of adult mortality and...

Direct measures of body mass of marine mammals are logistically complicated to obtain even for pinnipeds. An alternative method for mass estimation based on 3D imaging technology and automated processing algorithms, was tested in southern elephant seals ( Mirounga leonina ). Two models of artificial neural networks (ANN)—nonlinear neural network and self‐organizing maps—were trained to compute the volume and to estimate the ma...

Elephant seals, Mirounga spp., are highly dimorphic, having different energetic requirements according to age and sex, and foraging in various ecological and oceanographic contexts. Resource partitioning has been shown for the sub‐Antarctic populations of southern elephant seals, M. leonina , where colonies are surrounded by narrow shelves that deepen abruptly. In contrast, seals from Península Valdés (Argentina), in the north...

The only large mainland colony of southern elephant seals ( Mirounga leonina ) is on Península Valdés, at 42°S, in Argentine Patagonia. Censuses of pups have been carried out regularly there since 1970, and the population grew five‐fold by 2010. Here we use Bayesian modeling tools to make rigorous estimates of the rate of population growth, r , and to estimate survival and recruitment parameters that could account for the grow...

Southern elephant seals breed at Península Valdés (PV, Argentina) along 200 km of coastline. Annual pup counts at peak breeding season for the entire colony increased from 12,113 in 1995 to 14,350 in 2006. Two demographic subunits were identified in the North and South of PV with different trends in births numbers, sex ratios and harem sizes. Birth numbers increased in the South, but decreased sharply in the North. To explain...

A bstract Blood samples were collected from 156 free‐ranging southern elephant seals ( Mirounga leonina ) from Peninsula Valdes to study the variation in blood parameters related to ontogeny and the annual cycle. Samples ranged from newborn pups to adults. Interactions between age and sex showed different trends in ontogenetic changes of blood parameters (MANOVA, Wilkis' Lamb‐da 12,243 = 0.75, P vs . 20.3 g/dl) to adulthood (1...