Large-scale assessment of the presence of Darwin's fox across its newly discovered range

Abstract

The Darwin's fox is one of the most threatened carnivores worldwide and was thought to occur in only two isolated areas. Recently this canid was found in the Valdivian Coastal Range, between the previously known populations, but other than their presence, little is known about these populations. Here we report the results of camera trap surveys conducted between 2012 and 2016 (18,872 camera days), including surveys in 30 different sites—distributed along c. 400 km—and monitoring in two contiguous protected areas. Darwin's fox detection rate was higher when forest cover was higher or when domestic dog (Canis familiaris) detection rate was lower. Given confirmed presence, the detection rate was higher for sites in Chiloé Island, than in the mainland's Coastal Range. In mainland, we found evidence of dogs’ presence in most of the sites we detected Darwin's foxes. In the protected areas monitored, Darwin's foxes were found to use 12% and 15% of the area sampled in 2015 and 2016 respectively, although there was high uncertainty in the 2016 estimates due to low probability of detection. We did not detect Darwin's foxes in forestry plantations. Our findings provide support for a continuous distribution along the mainland's Coastal Range and Chiloé Island but we hypothesize—based on the major differences observed in detection rates between these areas—that local densities are lower in mainland than in Chiloé Island. Finally, Darwin's fox appears to be sensitive to human disturbance and these disturbances, especially dogs, are ubiquitous within its newly discovered range.