Right now the northern states are blanketed in snow, and stepping outside can be hazardous. Winter temperatures can dip below zero degrees Farenheit, and the wind chill pushes far below that. We can throw on layers or stay inside, but what do the birds do? How can 
we help birds brave the winter onslaught of freezing temperatures and battering snow?
Birds can make it through the winter without our help, but many people provide their bird visitors with a heated bird bath. Open water is hard to find in winter, and by providing birds with a constant source of water you will attract more birds to your yard. Some birds (not all) will eat snow, but the amount of energy it takes to process this snow into water is high.
So, you can make life easier for your backyard visitors with a watering dish that does not freeze over. You don’t need to buy a brand new bird bath – you can buy a small heater that you leave inside your current bird bath with an extension cord. But, it is a good idea to use some caution when using a heated bird bath as well. When temperatures drop too far, a bird’s feathers can freeze after taking a bath or even from the steam that comes up from the birdbath. This can be dangerous for the bird, even resulting in death.
Laura Erickson of the Cornell Lab of Ornithology has some good recommendations on how to deal with this problem. Here is a link to an article on her new book, “The Bird Watching Answer Book, Everything You Need to Know to Enjoy Birds in Your Backyard and Beyond“.
Here is the paragraph specifically regarding heated bird baths:
In a section titled “Birds Don’t Need Hot Tubs,” Erickson states: “I would never use a heated bath when temperatures were below about 20 degrees to prevent steam from coating feathers.” She recommends placing a grill made of wooden dowel rods over a heated bath to prevent bathing while allowing access for drinking. If the bird bath is frozen, Laura sets out a small plastic container of water near the bird food in the morning and brings it in when it freezes.
So, while a heated bird bath can make your backyard a winter birding bonanza, you also must keep the safety of your feathered friends in mind. Cornell has some suggestions on setting up a birdbath which can help both you and make the winter a better time for year for your backyard visitors.