Dogs gone wild: habitat use and ecological impacts of feral dogs in sub-Antarctic Chile

Feral dogs (Canis familiaris) are an emerging threat to biodiversity on Navarino Island, Chile, where they have become apex predators in the absence of natural carnivores. This study evaluated the spatial distribution of feral dogs and their impacts on native species, including guanacos (Lama guanicoe), upland geese (Chloephaga picta), and flightless steamer ducks (Tachyeres pteneres). Presence-only data collected during two field expeditions were analysed using species distribution models (MaxEnt) to predict habitat suitability for feral dogs and guanacos. Habitat connectivity analyses identified at least two potentially isolated feral dog populations. Using generalised linear and non-linear models, we assessed the ecological impacts of feral dogs, finding significant habitat overlap with guanacos, particularly in central areas of the island. This overlap corresponded to a reduced likelihood of guanaco occurrence, suggesting behavioural adaptations to disturbance and predation pressure. Upland geese exhibited a negative association with both actual and predicted feral dog presence, while flightless steamer ducks appeared unaffected. Furthermore, NDVI changes observed on Navarino Island compared to Torres del Paine, where no invasive species are present, are likely linked to the spread of invasive species and the decline of guanacos in the Magellanic forest, highlighting the cascading ecological consequences of feral dog invasion. Our findings emphasise the urgent need for feral dog management to protect vulnerable species and maintain ecosystem health, particularly in fragile environments where invasive predators can have disproportionate impacts. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=115 SRC="FIGDIR/small/652634v2_ufig1.gif" ALT="Figure 1"> View larger version (46K): org.highwire.dtl.DTLVardef@8a746borg.highwire.dtl.DTLVardef@1e12027org.highwire.dtl.DTLVardef@10617c6org.highwire.dtl.DTLVardef@102ccca_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIInvasive species presence leads to environmental changes and potential tipping points C_LIO_LIFeral dogs pose major harm as an invasive species C_LIO_LIEndemic wildlife adapts their behaviour such as habitat use to avoid dog predation C_LIO_LISpecies diversity and population stability are higher in areas with no feral dogs C_LIO_LIDogs in general should be removed from the wild C_LI