He says camera traps have identified 24 and the rest have been calculated using the unreliable pugmark method.
据他说，照相机拍摄到24只，而其余的则是依据足迹等不太可靠的方法计算得来。
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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.