Garter snakes give birth to live young rather from eggs. Be glad you have them since they will kill many things including other snakes that are dangerous such as rattlesnakes. Snakes of all kinds absorb moisture from the soil. Just so you know where it is you might let the vegetation grow up around the hole. That way you will not cut one when mowing as I have done. Snake lived but had a hard time sheding it's skin since everytime I saw after that extra pieces of skin were hanging from the cut.

Christie,

Yes, it sounds like a very typical garter snake den. You will tend to see the biggest numbers around this time in March when they start to emerge (one or two may even come out on warm days in January or February but they won't stray far from their holes then). They'll hang around the den for about two weeks and then disperse. Of course one or two might go to the den in August or some other time to escape the heat, but for the most part most will migrate away from dens later in March and return in mid to late October. The hole is probably relatively deep and probably holds many more than 5 snakes..maybe 30 or more. I have a den in my yard too and know of several in my residential neighborhood. It doesn't take much of a hole, a rock wall, or a stump for a garter snake den. Some of Missouri's other snakes require more extensive communal dens in deep cracks of bluffs. But garter snakes have pretty minimal den requirements. They don't need a back entrance although there could be one..but what you see could be their main, and maybe only, way in and out.

All of these are guesses based on the typical dens I am familiar with. Obviously there can be great variability.

You may see the snakes in mating balls this time of year near their dens. If you see 3 or 4 smaller snakes racing around and trying to get on a bigger one, you're most likely looking at a few frisky males trying to get with a female. Unlike humans, among garter snakes the females are usually larger than the males.

I'm glad to hear it's not typically a large hole. Being in the Ozarks, I was wondering if we might have a sink hole there waiting to cave in someday when I'm driving over it with our riding mower.
Paul - When I was looking for info on the web, I came across some articles about the garten snake dens around Manitoba. Sounds like something out of an Indiana Jones movie.
I've also seen a snake a couple times in the pipe from our sump pump. The pump has only kicked on about three times since we've lived here 20+ years. I would like to screen it off if I knew for sure that I wouldn't be trapping snakes inside the pipe. It drains at the back of our house but the pump is at the front of our house in our basement so the pipe is more than 30 feet long. I don't want that to be a snake den. This is the where the sump pump drains at the back of our house and not a garter snake. Maybe a baby black snake.

Paul - When I was looking for info on the web, I came across some articles about the garten snake dens around Manitoba. Sounds like something out of an Indiana Jones movie.

Here is a link that might be useful: Manitoba's Narcisse Snake Dens

HI I just want to know if I remove a snake from my pond and move it 1 mile away into a wheat field that is across a large irrigation ditch, flowing away from my 100 gallon pond or property, will the snake be able to find it's way back to my pond. I know they are good for mice etc., but I always hate when I see them eating my little pond fish. I've caught 3 Garter or field snakes in the last 2 days hanging around my pond and took them far away where I thought there would be a more adequate food supply for them. Thanks!

Moving almost any animal away from it's established habitat will result in it's death. We don't know all the complex details that make up a good living arrangement for a snake. And even if we put them somewhere that had everything they need, they might not find everything, or there might already be plenty of snakes living there, so an additional one will be chased away or might starve. If it doesn't find a den, it will become food for an owl the first night. If you don't want a particular animal on your property, then call animal control or dispose of it quickly and humanely yourself.