Predation risk in tree squirrels: implications of the presence of free-ranging dogs

    A study shows that free-ranguing dogs can pose a serious problem for the conservation of tree squirrels and other potential prey species

    It is known that small mammals show variations in their activity patterns because of resource use and predation risk, however, for most species, such as squirrels, these activity rhythms and the factors that determine them are poorly studied.. Near urban areas, squirrels might have to deal with an extra anthropogenic element that would affect predation risk: the presence of free-ranging dogs.

    The domestic dog is the most abundant carnivore in the world, with an estimated population of more than 700 million. Although most of these dogs are owned, many live partially or free-ranging. These free-ranging dogs represent a threat to many wildlife species due to direct predation, disease transmission, competition for resources, or limited spatiotemporal use by other species.

    Scientists of the Research Group in Game Resources and Wildlife Management of the Instituto de Investigación en Recursos Cinegéticos (IREC – CSIC, UCLM, JCCM), the Universidad de Córdoba, the Universidad Autónoma del Estado de Hidalgo (Mexico), and TRAGSATEC, have used camera trapping to investigate the activity patterns of three different squirrel species of the genus Sciurus, two squirrel species from Mexico (Sciurus aerogaster y Sciurus oculatus) and one from the Iberian Peninsula (Sciurus vulgaris), in the use of resources found in the soil, comparing these patterns with the community of their most important predators (Mexico: gray fox, Urocyon cinereoargenteus; ringtail, Bassariscus astutus ; Opossum, Didelphis virginiana; Spain: red fox, Vulpes vulpes, martens, Martes sp.) and with the presence of free-ranging dogs (Canis lupus familiaris). The objective of this work was to evaluate the risk of predation by the carnivore community on the squirrels when they descend to the ground by studying their temporal overlap, and to observe whether squirrels have different rhythms of activity adapted to the carnivore community in each study area.


    Free-ranging dogs can pose a serious conservation problem for tree squirrels, such as the red squirrel (Sciurus vulgaris) in the Iberian Peninsula, and other potential prey species.

    The results show that the three species of squirrels always descend to the ground during the day, showing a maximum peak of variable activity between 8:00 and 12:00 hours, with a moderate-high overlap between them. The overlap of the three species with the carnivore community was low, the same as with the main predators. However, the overlap with free-ranging dogs was moderate-high in all three squirrel species.

    The species of the genus Sciurus have adjusted their activity patterns of ground use to reduce predation risk by wild predators but not with free-ranging dogs, something which can pose a serious conservation problem for these species. This suggests that there is probably a conservation problem for many prey species and mesocarnivores due to the high abundance of wild and free-ranging dogs in many areas of the world.

    Despite growing evidence of the adverse effects of free-ranging dogs on biodiversity, management actions to reduce their effects are lacking. For this reason, the authors of the study urge public administrations to create management plans for free-ranging dogs in areas of high biodiversity.

    The scientific publication of this research is available at: