Most published studies in wireless passive acoustic monitoring (PAM) report an audio acquisition duration that is relatively short, from a few hours to a few months. That's what one would get by deploying an off-the-shelf battery-powered solution like AudioMoth or SongMeter.
I am curious about wireless PAM surveys that lasted for over one year on remote (off-grid) sites. What were the benefits and the challenges encountered?
I'm trying to establish a general state of the art, so feel free to bring up studies about any taxon: birds, bats, cetaceans, fish, land mammals, you name it. But i'm only interested in wireless sensors operating autonomously off the grid, as opposed to short periodic surveys or wire-powered devices. Towing a hydrophone to a boat would be off-topic for this question.
Specifically, it would be helpful to know if the recordings were made continuously or intermittently, with what source of power, and what connectivity. How often did humans physically access those PAM devices, if at all.
(edited on August 8th to clarify that my question is about wireless autonomous sensors)