Foraging, Predation and Sociality in Maras (Dolichotis patagonum)
thesisposted on 13.12.2012, 00:00 by Moira S. Sombra
Dolichotis patagonum (Rodentia: Caviidae) inhabits the central and southern desertic plains of Argentina and can weigh up to 10 Kg as an adult. Commonly called mara or Patagonian cavy, this large rodent is a unique model to address foraging/predation questions. This study examines the foraging dynamics of maras, to begin to understand the role of predation risk on habitat selection and sociality in maras and took place in the Sierra de las Quijadas National Park, Central Argentina. Here, maras feed mainly on three habitats that vary in opportunities and challenges for vigilance, food availability, and cover from predators. I offered maras a set of artificial food patches with different levels of sight lines and examined maras’ habitat preference and response to vegetation structure in two ways: a) food patches in clearly distinguishable open or covered areas, and b) food patches as a grid with equal feeding opportunities at each station. In order to evidence the use of the patches by maras or other herbivores, motion sensor camera traps were installed at the different stations. The activity in front of these cameras was then analyzed as part of maras’ temporal habitat use section. Maras foraged significantly more in open than in covered bushy habitats when pumas are present in the area on the triplets experiment (P<0.001). Maras also displayed a complex set of behaviors regarding territory defense (marking, aggression) in response to artificial food patches at the microhabitat level. Data showed that not only maras prefer habitats with low vegetation cover and good sightlines but also visit artificial food patches during hours of light more often than during the night. These findings suggest that predation plays an important role on maras’ habitat selection and use. Individuals foraging in pares alternated foraging and vigilance such that one member of the pair was vigilante at all times. In addition, results on the landscape of fear for maras supported the species’ sensitivity to poor sightlines. There was a significant difference between food left behind in patches with a higher removal for patches with lower plant cover.