Rats often nest in gardens and yards, especially if there is plenty to eat like fruits, vegetables and composted meats. It is essential that you get rid of the rats before they take haven in your home; however, in the meantime, make sure you have covered any holes or possible entrance ways into your home. You can take several courses of action to get rid of the rats yourself before you call in the professionals.
Clean up your garden. Pick up any dropped fruits or rotting vegetables everyday.
Don't use compost with fish, meat, chicken or anything that rats eat. They basically eat what we eat, so you may want to only compost leaves and other yard debris.
Place sheet metal around isolated trees. It should be a couple feet tall so that rats cannot jump over it. This will help if the rats are eating fruit or nuts right off your trees.
Use a commercial rodent repellent. Several on the market are suitable for your garden and are organic and safe to use around children and pets. Rat repellents are usually shaken around your yard or garden. They use scent, like fox, to deter rats from coming into the area. People can not smell the scent, but the rat's sensitive olfactory glands can.