Head up/down not reliable indicator for creatures this short or shorter
Head up/down is used as an indicator of the creature's alarm; if its head is down it is not alarmed and if it is up it is alarmed. The problem is that that only works for creatures whose height is greater than the altitude above the ground of the scent bag. Suppose you have a small coyote (or an opposum or a squirrel or anything lower than the bag) who is not alarmed but is interested in the bag. Its head will be up, sniffing the bag. In the case of this coyote, it is approaching the bag and looking at the bag and as a result it is head up (or neither to within a small margin of error), but it is not alarmed.
by mason_UWI scientist
This is very true, and this indicator may not be the best tool with every single species, but to be consistent it makes sense to collect it for everyone. With all of the data that this project is generating we should be able to get a 'signal through the noise' as not every coyote is small. I'm a little worried about opossum though, head up/head down stuff is quite difficult.
Additionally, feel free to be mark things as neither if you feel that there is not a clear head up or down in a particular photo.