Snakes and mice are the most common things I pull out of pumps. They can get in through the smallest openings. Where there are mice there are snakes and vice versa. I would put a little chlorine down that well.
Wells that are left open are just dead fall traps for all kinds of critters. I once bailed out an old well that had been left open in a field and it had 20' or so of rabbits stacked on top of each other. Nasty job. Lots of bones, hide, eyeballs, etc., all chopped up and mixed together. It took a lot of work but we did get that well cleaned out and usable believe it or not.
Also one time I forgot to check the 4" pipes that had been laid on the ground by the well overnight. Must have been a half dozen rabbits got in that pipe overnight. After I got the 600' of pipe put back in the well I couldn't get it to show any flow on the flow meter. After taken off the flow meter there was a glob of rabbit parts that looked like it had been in a pressure cooker. Could tell they were rabbits but couldn't identify one rabbit from another. Needless to say after that I always dropped a rod down the pipes as I was picking them up off the ground with the pump hoist. Every once in a while we would flush a rabbit out of the pipe when it went vertical. The rabbit would land right at our feet and bounce off us and the truck a few times before getting his bearings and making a getaway. Always good for a laugh. And saved the rabbits life.
Sorry. Couldn't resist. 5/8 just struck me funny.
