Identifying what animal or rodent is causing damage to your back yard is the first step to take. In this way, it will be easier to find the best deterrent for it. Most of the time an animal or rodent etc. is attracted to an area because there is a food source there. It could even be a certain kind of plant or shrub that you have in your yard. If you find this is the case, it might be wise to remove the food source completely to eliminate the appeal.
A barrier is another method you can try, one that is designed for keeping out wildlife. It could also take the form of a visual deterrent or a sound that scares the creature away.
Perhaps, after trying these or other methods, you find that they have not worked. A last resort measure to take is to capture the animal and relocate it. Ask the advice of your local animal control center or wildlife management agent first though, as they will be able to offer advise on what you should do.