They managed to track him down at the bottom of the cliff, where he had accidentally fallen, but the cliff was too steep for the climbers to go down.

track 作为动词时意思是"追踪、跟踪"，指通过线索或痕迹寻找某人或某物。 down 在这里是副词，表示"向下"的方向，与动词 track 搭配使用。 track down 是一个动词短语，意思是"追踪找到、追查发现"，强调通过持续努力最终找到目标。