When I moved our wooden garden bridge, I discovered that some creature has been making it a home. I'd like to keep the bridge in the garden, but I don't want to attract pests. (We had a rattle snake visit last summer, and I'm trying to get rid of any hiding places for snakes and snake food.) Anyone have ideas for what I can place under the bridge?
Many animals like being under structures, be it decks, houses or ornate bridges. Just a random pile of lumber is an invitation to pests.
1) Eliminate these habitats whenever possible.
2) Make these habitats less inviting. Many pests like a hiding place that is just large enough for their own body. By making the opening too large, too open, and the 'enclosure' or 'cave' less of a cave it is not so inviting. For example, do not stack firewood next to the house. Disturb the habitats often enough that critters will not move in, or are encouraged to move out. CAUTION! Poisonous snakes can be quick to move in, and dangerous to you when you disturb their resting place.
3) Fence or screen off all openings that lead to hiding places. Most of my clients have such screening around low decks to keep out skunks, 'possoms, raccoons, cats, and many other critters. Snakes are harder to exclude since they can enter through much smaller holes. Most larger animals can be kept out with 2" x 4" welded wire mesh. It is strong enough to do the job, but open enough for plenty of ventilation. You can add aviary mesh (smaller holes than chicken wire) to the 2 x 4 welded wire mesh for the strength of the wire, and the finer openings of the aviary mesh, and exclude smaller animals. Debris tends to build up against this mesh, though, and can invite rot and insects as it piles up and contacts wood like a deck, or the walls of the house.
4) If you are worried about digging or burrowing animals the screening needs to extend into the soil the right depth for the pest you are dealing with. Any burrowing animal can open a path which is later used by snakes, so excluding things like gophers and voles is a good idea.
5) Animals that climb are pretty much impossible to keep out. They will climb fences, trees, downspouts, and use all sorts of paths to get to the house or wherever they want. Excluding them by blocking all the entry holes is the best you can do.
6) Many animals are looking for food. Rotting wood, leaves, wood in contact with the soil, and many other things will encourage many types of bugs and worms. Then animals will come, hunting for the worms etc. Stop the animals by elimination the hiding places used by the bugs.
Specifically the bridge:
Make the bridge out of stone, brick or concrete so there is no wood to rot or come in contact with the soil.
Make the bridge high enough and small enough so you are not making a cave.
Screen the area under the bridge that might represent a cave to some animal.
I also learned a lot more about snakes from a client.
His area had TONS of voles.
Voles do not dig deep tunnels, but prefer to 'tunnel' under the leaves and thatch but on top of the soil, or just a little bit under the soil where it is still soft from many years of decomposing leaves etc.
Then snakes (rattle snakes and others) will follow those tunnels, hoping, I am sure, for a vole to eat.
However, the fencing plans for his yard had to include 6" minimum imbed with fine mesh to keep the voles out. This in turn kept the snakes out. He had very shallow soil, and hit bedrock very quickly, so 6" deep was pretty much all the soil he had!
Some pests will tunnel a lot deeper. Gophers, for example. (Except through bedrock)
Many pests will walk/jump/crawl across the surface.
So, a big part of the answer is knowing your local pests, and customizing the ideas to specifically exclude the local problem animals.