I found an absolutely consistent fix thanks to people in the comments (for PS4 at least).

So after killing your first snake, take the carcass back to the camp and drop it there; then you will be teleported to the "covenient location" within the camp. Save the game and reload (exit then enter the game, not load a game), and go back to the hunting spot, and you will always find one. I don't know if bringing the carcass back to camp has something to do with it, but I did it as a joke; I wanted to give Micah a snake of his kind. Then, when I reloaded the game and went back to the hunting spot, I found another one. Rinse and repeat; I found all four snakes in more or less 20 minutes.

This really helped me finding the rainbow boa because I was about to give up on my 5th try until the snake bit my leg I nearly threw my controller across the room.

I don't know about your game but I never spawn anywhere near the snake spawn. This spot does generate a snake regularly but the only way to trigger a new snake appearing in my experience is to save, exit the game then load the save. Save and load alone doesn't do it you have to exit before loading. Once I did that I got a snake every time. I'm pretty sure this method will work with other spawns as well, like the bull moose near Colter, the cougar along the road in west Elizabeth near the trapper and the panther in bolger glade.

I was looking for snakes for 2 and a half hours before going on YouTube to hopefully get some tips and thanks to you I got the ones I was looking for in 15 mins!

Cheers for that, mate! The Fer de lance was doing my head in!

It would of been nice if they gave you more time to explore the island you can’t go very far because of the guards and if you start a mission they all play back to back then your off the island

Thanks so much! I only needed one snake and it worked like a charm. I found another one before arriving Aguasdulces, in the first zone in which animals start to spot just when you cross the border to arrive to Guarma through the glitch in Epilogue (when wild pigs are the first animals you see and hear).

Thank you so very much your strategy worked like a charm I am currently in chapter 5 I shot a snake waited 5 minutes came back and found the exact one I needed you earned yourself a brand-new subscriber thanks again

Took 6-7 tries but I finally got the fer-de-lance at Stillwater, I was never able to find one on Guarma. Thanks so much! :)

Thanks, finally found the red boa this way!

I glitched in to guarma and the very first animal I saw was the Fer de Lance! Thanks for this guide I hope to get everything now so when the story brings me I can just blaze through and be done with it.