Are southern elephant seals re-invading mid-latitude grounds? New sightings and first birth records off the Chilean Coast

Abstract

The southern elephant seal (SES), Mirounga leonina, has an estimated abundance of 900,000 individuals and a nearly circumpolar distribution in the Southern Hemisphere. In Chile, the species inhabits three colonies in the Magallanes Region (54°24′S) and the northernmost sightings have been attributed to vagrant individuals. The aim of this study is to reassess the distribution of SES on the Pacific Coast. Censuses were conducted from 2004 to 2017, from 29°02′S to 29°16′S and from 38°22′S to 48°23′S. Data from social media and official landing records were also incorporated to complement the research sightings. A total of 72 SES were sighted in 40 haul-out sites; 42% of the animals were found in haul-out sites shared with the South American sea lion, 4% in wetland haul-out sites, and 54% in other haul-out sites. We recorded a parturition event in the Dallico wetland, at latitude 42°19′S, which establishes the northernmost location of breeding SES in the Pacific Coast. Our data show an increase in the number of adult and immature SESs sighted in middle latitudes during survey years with similar sampling effort (2007–2016). Interestingly, we corroborated the sighting of an adult female for 9 years in the Marine Protected Area Isla Chañaral (29°02′S), evidencing long-term fidelity to foraging regions in nonbreeding ranges of the species. The high productivity in the distribution area, where isolated and protected areas are located, makes these ideal places to find new foraging and resting grounds at middle–low latitude hotspots.