I would come down strongly on the side of being quite conservative as to what counts as evidence. As a general rule, we should presume honesty when considering evidence, but we should be very cautious if making any presumptions as to human error or the lack thereof.
So:
- spectrogram of a bat call
is fine, no different from an audio recording.
- a link to or observation field with DNA sampling info
is probably fine, provided that the possibility that the association between the observation and the DNA is mistaken is considered (i.e. how likely is it that contamination or human error has resulted in the DNA tested is not from the specimen in question).
- an illustration
can maybe be fine. But human fallibility needs to be accounted for very carefully. Presume honesty, but don’t presume that illustrations are accurate in every detail. It’s very easy to draw what you think you saw, or what you think you should have seen, rather than what you actually saw. Illustrations should not really be used for difficult identifications, especially where shape/structure features are important.
- an attached description or comment by the observer describing a sound or feature not depicted in the photo
Need to be very careful. After all, if something isn’t identifiable from the photo, but we give research grade from the description, how is that any different from giving research grade to an excellent description with no photo at all? I don’t think anyone here would advocate for that?
Again, presuming honesty seems reasonable. But don’t presume that someone isn’t fallible. If something is very straightforward and objective (e.g. “wintergreen scent to twigs”, “measured diameter at breast height of 72 cm”), that seems likely reasonable to use as evidence. But typically things are less so (e.g. “identified by call”, “appeared to be about a foot tall”). And at that point I don’t think it’s really evidence, it’s just affirming that somebody else’s identification process is probably right.