Predation risk can influence small mammal movements, route selection, and foraging strategies. Several studies in North America and Europe have found that 50-90% of travel distance by rodents is on downed woody material. Many small mammal predator species in North America hunt using auditory cues. Rodents may travel on downed woody material to reduce rustling of leaves and detection by predators. The field site was located in Chiquibul National Park, Belize. Due to a diverse predator assemblage, I predicted that small mammals at the field site would use down woody material for travel and escape. Chiquibul is 500,000 ha of contiguous humid broadleaf forest. Small mammals were captured using Sherman live traps and locally constructed mesh traps. Captured individuals were coated with fluorescent powder and following release their trail followed using an ultraviolet light. Changes in direction along the fluorescent trail were marked with wire flags, and distance and direction between flags was recorded. The linear distance of all downed woody material > 5 cm diameter and within 1 m of the trail was measured.
Results/Conclusions
The big-eared climbing rat (Ototylomys phyllotis), forest spiny pocket mouse (Heteromys desmarestianus), mouse opossum (Marmosa sp.) comprised the vast majority of captures. Following release, movements of these species were significantly non-random, with a directional bias. Although downed woody material was common within 1 m of the florescent trails, none of these three species used the wood as runways. The management of Chiquibul National Park, along with extensive observations, suggest that pit vipers, particularly the jumping pit viper (Atropoides nummifer), a small mammal specialist, are common at the study site. The hunting strategies of these pit vipers include the use of vibrations transmitted through substrate such as logs. The abundance and prey cues of the vipers may explain the avoidance of downed woody material by the small mammals.
