This paper presents a small animal body sensing/tracking system for uninterrupted and long-term activity monitoring in standard homecages. The proposed scalable design, comprising a thin layer of multiple resonators, overcomes the limitations of the camera-based systems. The animal body tissue influences the electromagnetic properties of the resonators at frequencies >100 MHz and can be detected. The proposed sensing design is implemented, and the measured results verify its capability in detecting a small animal model. The experimental results show the sensitivity of the design to the animal body location over the array with significant and detectable changes in resonance frequencies.