New records of invasive mammals from the sub-Antarctic Cape Horn Archipelago
The southernmost archipelago of the Americas is dominated by invasive mammals that outnumber their native counterparts. Despite the relatively low ability of most invasive mammals to cross cold sea water channels, invaders are apparently colonizing new islands. Our objective was to provide an assessment of the expansion of invasive mammals within these sub-Antarctic ecosystems, determine whether human-mediated movement of invasive species is a plausible dispersal mechanism, and identify areas likely to be colonized in the near future. We report a decade of fieldwork (2006–2017) in 44 sites on 13 islands within the Cape Horn Biosphere Reserve including opportunistic and systematic camera trapping, carnivore diet, questionnaires, small mammal trapping, and walks/transects. We found new records of invasive mammals on seven islands, particularly for American mink (Neovison vison) and American beaver (Castor canadensis). Interviews with fishermen showed that mink, dogs (Canis familiaris), and small rodents are likely passengers in vessels. Finally, species distribution models revealed that the putative invasive-free Cape Horn National Park (55°S) is suitable for several invasive species, suggesting a high risk of invasion if species are introduced. We conclude that it is urgent to implement barriers to dispersal to prevent further invasion. In the case of dogs and cats (Felis catus), the first step should be control actions that target pet owners. Finally, we highlight the need of systematic, long-term biodiversity monitoring and citizen science in the Cape Horn Archipelago and common conservation guidelines for the terrestrial sub-Antarctic ecosystems.
KeywordsAssisted dispersal Conservation Free-ranging domestic animals Islands Monitoring Range expansion Vertebrates
We are grateful to the local community and fishermen of the Cape Horn Biosphere Reserve, who shared their knowledge with us, to A Mansilla, and numerous volunteers who helped in the field. Our special thanks go to the Chilean navy for facilitating maritime transport to the navy posts. We would also like to thank the National Forest Corporation (CONAF) for their support, especially X Álvarez, A Silva, L Ramírez and M Lopetegui. N Ward, E Butikofer, A Pietrek, and two anonymous reviewers made valuable comments on an earlier version of the manuscript. The University of North Texas (UNT), the Institute of Ecology and Biodiversity (IEB), Pew Charitable Trusts, and Corporación de Fomento de la Producción (CORFO, 16BPER-67004) funded the study. E Schüttler and E Silva were supported by the Comisión Nacional de Investigación Científica y Tecnológica (PAI-CONICYT No. 79140024 and FONDECYT Iniciación No. 11171006), and R Rozzi by the Millennium Scientific Initiative (No. P05-002) and Basal-CONICYT (No. PFB-23).
Compliance with ethical standards
Conflict of interest
We have no conflict of interest to declare.
Permission to work in protected areas was provided by the National Forest Corporation (CONAF, Resolutions 711/2014 and 158/2017). The Agriculture and Livestock Service (SAG, Resolutions 6518/2013, 8547/2014, and 1728/2015) issued the permits for rodent trapping. The Scientific Ethical Committee of the University of Magallanes, Chile, certified ethical approval of the questionnaires with navy families (Certificate 25/05/2015), whereas the local Chilean navy authority provided a formal permission (Resolution 119/2015).
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