Paw print, or pugmark, tracing is another common technique for counting tigers.

爪印和老虎足迹同样是常计算老虎数法。

The researchers then use the pictures to measure the length and width of each pugmark, the angle between toes, and 10 other variables to establish an ID.

研人员照片来测老虎脚印长度和宽度以及脚趾之间角度，以及10种其他变来确定不同老虎“身份”。