In 1951, a batch of 24 young animals of both sexes of Chilla or Grey fox Lycalopex griseus from continental Magallanes region, Chile -and perhaps also from adjacent continental Argentina -were released at Onaisin (65 km ESE Porvenir town, 53°18′S) on Tierra del Fuego Island in southernmost South America, to control a European rabbit (Oryctolagus cuniculus) irruption that was considered detrimental to sheep (Ovis aries) ranching. Up to now, no attention has been paid to the temporal course of that introduction. Here we provide a historical account of the presence of foxes on the Tierra del Fuego Archipelago, starting with Charles Darwin account of 1839 until present. We also review the regulatory framework concerning hunting of those foxes and tally their culling for export of pelts. Finally, we provide estimates of the abundance of Chilla foxes on Tierra del Fuego Island for the period 1999-2007 and for 2021, and highlight their current spread. These translocated foxes have become an abundant and functional part of both steppe and forest ecosystems on the Fuegian archipelago, even though they are killed by hunters, without spatial, temporal, or numerical limits. We conclude that interesting scientific opportunities are being missed regarding the population genetics of a species that may have left founding effects and genetic bottlenecks in Tierra del Fuego, and perhaps some peculiar continental markers among the island population. We also raise the question whether this introduced native species may be deemed invasive, calling for research to determine its impact in its new environment.

Background Little is known about the California Quail (Callipepla californica) as an invader in Chile and Argentina. Our goal was to review the history of its introduction and to provide updated information on its spread and current geographic distribution in those two neighboring countries, together with information on its body measurements (weight, wing length, and tail length), diet (granivory, frugivory), parasitism (endo and ecto), and other interspecific interactions (competition and predation), including hunting by humans. Methods and result We conducted a selective review of the history of introduction, distributional records, and biological features of C. californica, as recorded in mainstream journals, landmark monographs and books, and internet sources. We also measured specimens collected in central Chile and analyzed their stomach contents. We report that the California Quail was first introduced to Chile in 1864, and it now spans ca. 2,800 km in the country. From stocks in Chile, this bird was back-introduced to California (USA), and also introduced to Argentina in the 1920s, now spanning ca. 1,400 km in the country. It is currently abundant and legally hunted in both countries. In Chile, its non-breeding diet is strongly granivorous. In Argentina it feeds similarly. In Chile, endoparasites are three species of nematodes, one of cestodes, and two of coccidian protozoans; ectoparasites are three species of hard ticks, one of mites, and two of chewing lice. No such data are available from Argentina. In Chile, combining autumn and winter samples we obtained mean weights of 194.4 (± 9.0 SD) g for 21 adult males and of 183.9 (± 14.3 SD) g for 10 adult females, figures similar to those reported for C. c. brunnescens in California (USA), which we suspect is the subspecies now spread over in Chile and Argentina. Discussion We propose that interesting scientific opportunities are being missed regarding the population genetics of a species with introductions and back-introductions that may have left founding effects and genetic bottlenecks in Chile and Argentina, and perhaps some peculiar “Chilean” genetic markers among California (USA) populations. We also raise the question whether this introduced species may be deemed invasive, calling for research to determine its impact in its new environment.