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

爪和老的足迹同样的计算老数量的方法。

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.

研人员这些照片来测量老的长度和宽度以及趾之间的角度，以及10种其他变量来确定不同老的“身份”。