Long-term monitoring for conservation: closing the distribution gap of Arctocephalus australis in central Chile

Objectives Here, we present the first record of stable colonies of the South American fur seal (Arctocephalus australis), in an area where their presence has never been documented (hereafter distribution gap), as well as an update of the current distribution range of the species in central Chile. Results A national synoptic aerial census of pinnipeds was performed during the austral summer of 2019 on the Chilean coast. An additional aerial census was conducted in the same area during the austral spring of 2019 as well as a maritime census during the austral summer of 2020. The data showed the presence of South American fur seals in central Chile within their well-known distribution gap. The total abundance was registered in three colonies where fur seals were sighted: one non-breeding colony, Punta Topocalma (summer 2019: mean = 46 +/- 3; spring 2019: mean = 9 +/- 1); and two breeding colonies, Punta Curaumilla (summer 2019: mean = 595 +/- 7; spring 2019: mean = 45 +/- 4; summer 2020: mean = 744 +/- 5) and Isla Santa Maria (summer 2019: mean = 246 +/- 6). Specifically, we suggest that it is crucial to elucidate the origin of the described settled colonies, and to determine whether there has been an augment in the distribution range from either the northern population, the southern population, or both simultaneously.

Automated summary

This study presents the first record of stable colonies of the South American fur seal in central Chile and updates the current distribution range of this species in the region. Aerial and maritime surveys conducted in 2019 and 2020 confirmed the presence of fur seals in the well-known distribution gap. The study suggests the need to investigate the origin of these established colonies and determine whether there has been an increase in the distribution range from the northern, southern, or both populations simultaneously.