Frequent checks of live traps require enormous amounts of labor and add human scents associated with repeated monitoring, which may reduce capture efficiency. To reduce efforts and increase efficiency, we developed a trap-signaling device with long-distance reception, durability in adverse weather, and ease of transport, deployment, and use. Modifications from previous designs include a normally open magnetic switch and a mounting configuration to maximize reception. The system weighed <225 g, was effective ≤17.1 km, and failed in <1% of trap-nights. Employing this system, researchers and wildlife managers may reduce the amount of effort checking traps while improving the welfare of trapped animals.