Andy’s reply is spot on, both regarding powering options and long cable techniques. I know Chris Watson uses 200m cables on occasion and he says he hasn’t noticed any issues stemming from this. If you go this route make sure you cover your XLR connectors and possibly hide the cables around your mics so that wildlife doesn’t think it’s snakes or the like.
I do a lot of drop and leave overnight recordings, and on top of what Andy mentioned I also use a Cinela blimp that keeps my mics dry even in heavy rain. I also leave my recorder bag in a dry bag and tie it to a tree or big rock. The biggest problem with unattended recording is that you never know what you’ve recorded. More pedantic recordists will never do it, but I’m fond of it and I love listening back to hours of overnight recordings (sort of like opening presents, youy never know what you get!).
I’ve always been wary of wildlife interfering with my rig, but so far I haven’t had any problems. I have recordings of boars coming really close and baboons bumping into the tripod, but it seems like my rig was never that interesting for them. One thing I always avoided is keeping food in my recorder bag, since it would definitely make them curious.
One other thing I should mention is you don’t need a really expensive rig for long recordings. On occasion I will leave my Sony D100 out overnight as well, and I think it can easily do a 20-hour session on 4 Eneloop 2500 mAh batteries. It also sounds quite good for a small handheld.
There are a bunch of different ways, and yes, battery power is necessary for them all.
One popular method is drop-and-retrieve, where you leave the gear (recorder and mics) secured in a location overnight. This allows you to put the most distance between yourself and any potential wildlife that will come around. This also allows for the most compact possible instance, easy for hiking-in and hiking-out. Just be aware that many animals are curious and will investigate your equipment. It’s a good idea to keep anything possible (i.e. the recorder itself) inside some sort of indestructible case that rodent teeth, large carnivore jaws, and curious primate hands can’t get through.
I’m fond of long mic cables myself as I like to listen while I record. My standard setup uses 90 meter cables, long enough to get away from my tent to where most wildlife in my area won’t be too skittish. I know folks using CAT-6 extenders that reach 225+ meters. I use this method with a Sound Devices MP6 (formally a Zaxcom MAXX) and external batteries. With a single high capacity USB-C powerbank (Anker 26800) the MP6 will power 3 mics and record well over 12 hours (close to 20 if it’s not cold).
If you need AC for your particular piece of equipment, you can try a dedicated product like an EnergyBar or Anker’s PowerStation, or you could even rig your own for lower cost by using a common 12V battery and a power inverter. Be careful not leave the power inverter out all night near your microphones, though, as most have tiny fans that will create noise.
Depending on your gear, you can get batteries that will easily run 14-20 hours or even far longer. For instance, you could use a Core battery with a P-Tap adaptor or an NP-1-style battery with either a cup adaptor or P-Tap if available for your particular piece of gear.