From what the iNat staff has described, the “Dead” annotation also for when something is dying, or dies shortly afterwards, as @abersbird pointed out.
See these posts:
https://forum.inaturalist.org/t/lets-talk-annotations/627/135 (" Dead - meaning that evidence shows the organism is dead or shows signs of imminent death.")
https://forum.inaturalist.org/t/lets-talk-annotations/627/139 (“within minutes or an hour or two at most”) - this was in response to a request for clarification of what time period qualified as “imminent” in the previous post.
That could absolutely apply to an audio recording.