Meeting Abstract
Animals must regularly negotiate complex 3D terrain in trees. They are able to accommodate large changes in substrate compliance, height, and gap distance without falling to the ground, which would result in exposing them to potential predators. The discontinuous arrangement of substrates in arboreal habitats continuously challenges animals to make choices about which substrates to move over and which to avoid. However, by avoiding some subset of the available substrates, due to branch diameter, compliance, or other properties, animals must make longer paths through the trees or to the ground, which will incur an additional locomotor cost. Therefore the goals of this study are to determine substrate use and path lengths of squirrels (Sciurus carolinenesis) in the field to examine if trade-offs occur between safety and economy. On average, paths were approximately sixty percent longer than the shortest, straight-line path between starting and ending points. Further, because squirrels spent much time on the ground, and climbed to and from the ground on large stiff branches, both the diameter and stiffness of branches was higher than estimates of average branch properties from transects through the study area. Our data suggest that there is a trade-off between branch selectivity and locomotor cost and that squirrels in our study prioritized safety over economy.
