I have approx one acre and the yard is tore up with holes and what appears to be underground tunnels. As I walk across the yard I sink a few inches in the soil. I assume whatever the varmit is; mole,mouse,snake,or whatever, they move at night. Do I sit outside in my guille suit with a flashlight taped to a bb gun and start blasting what ever I see? If I could find out what they are maybe I cound get rid of their food source ,poison, traps I don't know. Any suggestions anyone?? Andrew

Before you start blasting away with your BB gun and setting out poison or traps of any kind, then you had better check your county by laws to see just what you can do. Best advise is hire a company who deals with this type of extermination. No, poison, no matter what you think, is not a good option. Think before you do anything that will harm other animals in the neighbourhood.

However, we do have some very good pest control people around here.

Tick

It's not likely a mouse or a snake, but it more than likely is a vole. Voles (Meadow Mice) Management Guidelines--UC IPM

Only a guess at this point.

Ours were voles. We got 23 of them by putting a regular mouse trap at their access hole, baited with peanut butter. Then put a bucket of some type (or big flower pot) over the trap to keep other animals away. It is also advisable to wear plastic gloves while handling the trap to keep human scent down. Believe it or not, the 23 we trapped came from an area about 15 by 15 feet.

It does sound like a vole or mole infestation. The primary difference between the two is diet. Here are links to controlling both.

Mole Control | Lawn Care | Garden Pests | Mole Control

Vole Control | Field Mice | Moles | Meadow Voles

If you live in North America, an additional consideration are gophers. Gophers are very common where I live - more common than moles or voles.

Voles live in burrows but will run on top of the ground over the same route, in areas where the vegetation will hide their runs. Their habitual use of these runs will create trails in the grass.
Voles (Meadow Mice) Management Guidelines--UC IPM

Do you have mounds of dirt on your lawn?

Moles live underground. They create two types of tunnels - one deep and one along the surface. The surface runs are more likely to be in your garden than in your lawn and are indicated by raised ridges. The mounds they create are often circular, volcano shaped in profile.
Moles Management Guidelines--UC IPM

Gophers are common lawn pests in the United States. They leave crescent shaped mounds in lawns and orchards. My bet is gophers.
Pocket Gophers Management Guidelines--UC IPM

Ground squirrels also live in burrows, and can tear up lawns leaving dirt all over the place. But they leave their burrows open, (whereas moles and gophers usually plug their holes.) And ground squirrels are diurnal and often seen scurrying about. Ground squirrels hibernate during the winter and wouldn't be seen at this time.
California Ground Squirrel Management Guidelines--UC IPM

When I re-read your question I note that your yard/lawn/property is one acre. If the damaged area is relatively unmanicured, voles could be the problem. Voles prefer cover to run through, they tend not to plug their burrow openings. Look for the trails in the grass. Besides other damage they gnaw on the bark of trees sometimes girdling the trunk.

Voles: UC IPM Photo

Gophers: UC IPM Photo

Moles: UC IPM Photo

Ground squirrels: UC IPM Photo

The yard is mowed regularly. The access points into the tunnels are holes that are left exposed. There are no large mounds of any sort and haven't been able to examine trails or any trapping because the weather here has not been good. I'm in the southeastern US and as soon as weather permits I will try everyone's suggestions and post my finding. Thank you all