a couple of relevant threads:
- https://forum.inaturalist.org/t/observations-of-absence-vs-presence/1298
- https://forum.inaturalist.org/t/can-i-upload-older-photos-as-observations/3259
in a nutshell, there aren’t great standard ways in the system to record absence, but loading old photos as observations can be quite valuable.
https://forum.inaturalist.org/t/photos-of-animals-shot-during-hunting-ok/16261