痕迹拍照方法（以足印为主）Best Practices for track and sign photography (with a focus on tracks)
总结：足印标准照—视角在足印正上方，水平面放参照物（尺最佳，物品/手其次）
大多时候，除了一些特征明显的痕迹，在现场进行辨识远比通过几张照片判断有优势。这篇贴子向大家分享一些能将重要判断依据体现出来的拍照方法，以便帮助辨识。
1) 在图中放一个参照物。
尺子永远是最佳的参照物，尤其对于尺寸很小的足印来说。没有尺子的情况下，在痕迹旁放一个手边的物品/手/脚是次佳选择。待之后有测量条件时，在观察记录中备注一下物品/手/脚的尺寸，或附一张物品/手/脚和尺子的照片。
无论选择哪一种参照物，和痕迹放在同一个平面，得出的尺寸才最准确。因此，对于陷入雪地，泥地较深的足印，可以将参照物向下压到水平面上再进行拍摄。
2) 拍照视角：足印正上方。
足印的判断需要考虑形状，长宽等等，因此一般而言，拍照的视角与足印保持水平最能够体现出所有特征。
1，2例子：https://www.inaturalist.org/observations/166185666
3) 痕迹特写+环境照。
微环境往往对痕迹判断很重要，比如犬科和鼬科动物喜欢将粪便排在明显位置来形成视觉与气味标记（道路中间，石头上…）；而一些猫科动物更喜欢在树下排便，或有埋粪的习惯。在痕迹照片以外，以文字描述或照片形式提供充分的环境信息对判断会有很大帮助：水边，山脊上，密林中，树下，石头上，落木上，洞中……
例子：https://www.inaturalist.org/observations/189675900
4) 成组的足印，足迹链。
许多科级或种级的动物有他们的“自然节奏”，即常用的步态。在单个足印特征不明显的情况下，成组的足印或足迹链往往也能够帮助缩小可能物种的范围。比如这条观察中犬科惯用的side trot（https://www.inaturalist.org/observations/125600239）， 以及这条中松鼠常用的bounding步态（https://www.inaturalist.org/observations/148617894）。
欢迎大家在评论区交流，补充，提出问题或其他想了解的内容！
Quick summary: Standard track photo – angle directly above the track, placing a scale reference on the same plane (ruler is best, an object or your hand works too)
Most of time, other than signs with obvious features, identifying a sign on site has much more advantage than trying to do so through a few photos. This post shares some photo practices that showcase important id points to help with identification.
1) Include a scale reference in the photo.
A ruler is always the best reference, especially when it comes to very small tracks. When you don’t have one, placing an object on hand or your hand or foot next to the sign would be the next best option. When there’s the opportunity to measure, make a note of that object/hand/foot’s size in the observation, or include a photo of the object/hand/foot with a ruler.
Whichever reference you use, putting it on the same plane as the sign allows for most accurate measurements. Thus, when a track is deep in snow or mud, consider pressing the reference down to the same plane to take a photo.
2) Angle of photo: directly above the track.
Track identification takes into consideration the shape, length and width, etc. Thus, a photo took from right above is often best at showing all the features.
Example for 1 and 2: https://www.inaturalist.org/observations/166185666
3) Close-up of the sign + environment photo.
Micro-environment is often critical in sign identification. For example, canids and mustelids like to defecate in conspicuous places to form visual and scent markings (middle of a trail, on top of a rock…), while some felids prefer to defecate under a tree or have the habit of burying scats. Other than photos of signs, recording environmental clues through textual description of photos will be immensely helpful in identification: next to water, along mountain ridge, among dense woods, under a tree, on top of a rock, on a fallen log, in a den……
example: https://www.inaturalist.org/observations/189675900
4) Sets of tracks, trail.
Many families or species of animals have a “natural rhythm” – a common gait their use. When a sign track doesn’t show clear features, sets of tracks or a trail can help narrow down the possibilities. For example, the side trot that canids like to use (https://www.inaturalist.org/observations/125600239), and the bounding gait squirrels is often seen with (https://www.inaturalist.org/observations/148617894).
Please feel welcomed to chat, add on, ask questions or write down other contents you’d like to know in the comments!
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