We investigated whether domestic dogs (Canis lupus familiaris) influenced the use of space by chilla foxes (Lycalopex griseus) in southern Chile and tested the hypothesis that dogs interfere with chillas. We used scent stations and occurrence of scats within systematically placed plots to assess habitat use by both species and to test whether dogs were associated to the use of space by chillas. Activity data were obtained from captures for both species, and telemetry for foxes. Diet of both species was analysed in order to tease out the potential existence of exploitation competition.We found that, when active, chillas used prairies more and native forest less than expected according to availability, whereas inactive chillas (during the day) preferred native forest, the only habitat type that dogs did not use. The odds of dog occurrence increased at shorter distance to human houses, whereas the inverse pattern was observed for chillas. Poisson models showed that the number of chilla visits to scent stations was negatively correlated with the number of dog visits. We observed dogs persecuting and/or killing chillas which was also corroborated by local people that used dogs to prevent chilla-related poultry losses, supporting the idea that dogs harass foxes actively. The analysis of scats showed that dogs fed mainly on house food and domestic ruminant carcasses whereas foxes fed on hare, hens, mice and wild birds, thus suggesting that exploitation competition is not a strong alternative hypothesis as a proximate cause for the patterns observed. We conclude that dogs seem to constrain the use of space by wild carnivores via interference.
We assessed the importance of potential sources of mortality for the Vulnerable southern pudu Pudu puda in southern Chile using the clinical records of wildlife rehabilitation centres, necropsies of animals found in the field and a review of the diet of potential predators. To assess whether the identified mortality sources operate in nominally protected areas, we conducted a camera-trap survey in two areas to determine the presence of pudus and their potential predators. Predation by domestic dogs Canis lupus familiaris and car collisions were the commonest causes of pudu admissions to rehabilitation centres (35 of 44) and of deaths of animals encountered opportunistically in the field (seven of 14). Field data suggest that poaching could also be an important threat to pudus. Pudus were detected in both areas surveyed, accounting for 15.6% of mammal detections. Dogs accounted for 47.8% of all detections of potential predator species, followed by pumas Puma concolor (17.4%), guignas Leopardus guigna (17.4%) and chilla foxes Lycalopex griseus (17.4%). The literature survey implicated only pumas as important pudu predators among native carnivores. Our data suggest that, aside from forest loss, dogs, road kills and probably poaching are important concerns for pudu conservation. Our frequent detections of free-ranging dogs associated with roads within nominally protected areas suggest that long-term efforts to conserve pudu will require not only the protection of remnant native forest but also substantive environmental education to modify dog management near protected areas.
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