To clean birdbaths, use 9 parts water to 1 part bleach. In the winter, when temperatures are cold, water in birdbaths will freeze. It is important to have thawed water for the birds. A heater or de-icer is a device that is placed into the bird bath to thaw the water. Some birdbaths come with built in heaters.
Birds also find dripping water appealing.
Birds that do not normally come to your feeder such as flycatchers and thrushes may be attracted into view with dripping water. You can provide dripping water with a dripper or by making your own. To make your own dripper, you will need a 10 quart pail. Drill a small hole at the lower edge of the pail. Fill the pail with water and suspend it approximately 2 feet above your bird bath.