Dispersal is a crucial characteristic for animal adaptation to their environment, but it can be influenced by various biological and environmental factors. In the case of the reed voles (Microtus fortis), which lives in family groups with male offspring predominantly responsible for dispersal, the question arises as to whether individual members with smaller body size, lower aggression, and timidity disperse earlier due to competition for territorial food and spatial resources. To test this hypothesis, an observation device was constructed to record the dispersal behavior of reed voles. This device consisted of three densely packed and homogeneous food patches made of fresh crabgrass (Digitaria sanguinalis) leaves. Surrounding each food patch, we placed transparent glass observation boxes, and transparent plastic tubes connected the three food patches, serving as channels for animal dispersal. We released offspring members of reed vole families into the food patches, which were scented with their own family odor. The experimental approach involved the implementation of clipped fur markings and video recording techniques, as well as post-experimental slow-motion video replay. We measured the foraging behavior sequence and parameters of individual members on the food patches, as well as the behavioral processes and parameters related to dispersal to other food patches. Additionally, we calculated the ratio of body weight, aggressiveness, and boldness of the first individuals to disperse compared to the total number of families in the group. This allowed us to assess the impact of individual body weight, aggression, and boldness on dispersal. The results showed that individuals with smaller body size, lower aggressive, and timidity exhibited a significantly longer delay in foraging initiation compared to individuals with larger body size, higher aggressive, and boldness. Surprisingly, the rate of initial dispersal among the smaller, less aggressive, and timid individuals was significantly higher than that of the larger, more aggressive, and bold individuals. However, the smaller individuals also had a significantly or extremely significantly longer dispersal start time compared to their larger counterparts. The results suggest that as reed vole family members age and face increased competition for food and spatial resources, individuals with larger body size, higher aggression, and boldness force the smaller, less aggressive, and timid individuals to disperse earlier. This finding highlights the influence of individual characteristics and resource competition on the dispersal behavior within the family group. In conclusion, our study reveals the dynamics of dispersal behavior in reed vole family groups. As individuals grow older and competition for food and spatial resources intensifies, larger, higher aggression and boldness individuals tend to exert pressure on smaller, less aggressive, and timid individuals to disperse earlier. These findings enhance our understanding of the factors shaping dispersal behavior in animal populations and contribute to the study of animal adaptation and population dynamics.