Effects of social group odors on individual foraging behavior of family groups in reed voles ( Microtus fortis )

The effect of social group odors of family or non-family groups present in food patches on individual foraging behavior of family groups, and their intake rates is still unknown. To evaluate the effects of odors from family and non-family groups on the individual foraging behavior of family groups in reed voles(Microtus fortis), the foraging behavior and behavioral parameters of voles foraging in homogeneous food concentrated patches with bedding materials from family or non-family groups comprising fresh crabgrass(Digitaria sanguinalis) leaves were measured. The results showed that familiar social group odors significantly shortened the foraging decision time of individuals of family groups, the proportion of vigilance time of individuals of family groups for sniffing and upright scanning decreased, and the proportion of vigilance time for scanning, staring, and listening increased; therefore, the foraging interruption time of individuals of family groups was significantly reduced, and their intake rates increased significantly. However, unfamiliar social group odors dramatically increased the foraging decision time of individuals of family groups; the proportion of time for sniffing and scanning increased, and the proportion of time for upright scanning, staring, and listening in individuals of family groups dramatically decreased. Therefore, the foraging interruption time of individuals of family groups increased significantly, and their intake rates decreased. The results revealed that environments with familiar social group odors caused small herbivorous mammals to spend more energy on observing behavior and monitoring alarm signals of other members in family groups to avoid interfering competitions and risks. Meanwhile, in environments with unfamiliar social group odors, individuals of family groups adjusted their energy used for vigilance risks from depending on other members in family groups to self-reliance.