Or indeed, any other animal for that matter? I may sound insane, but it seems like great fun to me to sneek up on unsuspecting NPC's as a wild crocodile, or soar through the air as a bald eagle. Infact, as you can see from the video below, that's a really great way to explore the game's jaw-dropping environments.
Well, it's all possible thanks to a new mod which allows you to swap out Arthur's model for any other animal in the game, and interestingly, you're even able to take on that animal's quirks and abilities, such as being able to fly if you change the model out for a bird.
There was a similar, albiet official, feature in Grand Theft Auto V, so I wonder if the ability to do this is somehow a hang-over from that game. Regardless, it's great fun to do, although it does come with a few caviats.
Don't try and go online with this, or indeed any, mod installed. Apparently it can end badly, with the Rockstar Games Launcher warning that "unexpected files" have been found and that trying to use unofficial modifications may result in "being banned form online content"
The other prudent move is to back up any saves, as they may very well corrupt after doing this. The game autosaves all the time, so I highly recommend backing up before using any mod.
If you're aware of the risks though, you can download the mod here, there's a bit of setup involved, and it works as a trainer, meaning it's a seperate executable that has to run while the game does so it can manipulate the game in active memory. It features other functions you'd expect from a trainer, including teleportation and health / ammo cheats.
Oh yeah, and be careful up there...