LAUSR

The foraging behavior of small mammalian herbivores is the outcome of adaption to specific habitats. It is unknown whether vision obstruction caused by plants surrounding food patches affects foraging vigilance in small mammalian herbivores, resulting in variations in their intake rates. To evaluate the effects of the height of surrounding obstructs on the behavior sequence and intake rate of voles (Microtus fortis), we devised concentrated food patches of fresh leaves of clover (Trifolium repens) that were obstructed by three heights of brown paper to imitate the vegetation obstruction to vole vision around the food patches. The sequence and parameters of vole foraging behavior were measured to examine the effect of vegetation heights on their intake rate. No significant difference was detected in the foraging subject with different heights of obstruction in foraging behavior. The dynamic analysis of variation in foraging behavior parameters showed that in each biting bout, individuals maintained the total foraging interruption time by modulating the frequency and duration of vigilance behavior in each foraging bout, thus maintaining a steady ingestion time. The results also indicated that the voles maintained their intake rates at different levels of vision obstruction via altering and optimizing their behavior. These results verified the instantaneously dynamic change of energy gain by measuring the actual foraging interruption time caused by vigilant behavior. The variation in vigilance intensity, i.e., vigilance frequency, in voles did not reflect the cost of decreasing food