Abstract A major problem in studying bird movement in many countries is data scarcity, precluding information about the spatial and temporal properties of avian distribution and dynamics as well as their consequences for human lives. We address this problem by proposing an innovative approach based on the relation between counts of signal attenuation of wireless communication to the presence of birds across or near wireless links of cellular backhaul networks. Wireless point-to-point communication links, on either ground level or earth-satellite links, cover the globe. We statistically relate between signal attenuation in terrestrial Commercial Microwave Links (CMLs) and bird migration. Because modern communication systems measure and often log signal levels routinely, we propose using existing signal level measurements of cellular and other wireless communication systems around the world as sensors for monitoring of bird movement. Using actual measurements from operational CMLs, we show that the daily cycle of signal attenuation during bird migration periods matched that of waterbird migration traffic rate recorded by nearby bird radar. This demonstrates the potential of the proposed method for opportunistic bird movement monitoring by CMLs across the globe, with no additional hardware installation, maintenance or communication costs.