A bird can survive a night of subfreezing temperatures, but it still needs water the next morning. That’s a problem when every puddle, birdbath, and shallow stream in the neighborhood has frozen solid.
A shallow bowl of fresh water is enough to help. A winter birdbath just takes a little more care than a summer one, mostly around heaters and keeping birds from getting soaked in extreme cold.
Why birds need water even when it’s freezing
Birds lose water every time they breathe. The moist lining of their lungs evaporates a little with each breath, and they lose more through their skin and their waste. Small birds lose it faster for their size, for the same reason they lose heat faster: more surface area per ounce of body (here are the numbers).
Wild birds have workarounds. A seed-eater makes some water inside its own body when it burns food for energy, and insects carry water too. But those tricks cover only part of what a bird loses, so most of them still need a drink every day.
Open water isn’t critical in winter. Birds conserve water well and can get some from snow or icicles. A bath just makes drinking and bathing easier, especially where liquid water is scarce, and melting snow costs energy a bird could spend staying warm. Birds that do find open water tend to pile in and drink together.
Bathing matters in winter as well. Splashing around cleans feathers and clears out parasites, and clean feathers hold heat better than matted ones. An open bath saves some of that heat and helps them keep their insulation in shape.
What kind of birdbath works in winter
Start with the material. Ceramic cracks in the cold, and concrete does too and is hard to clean. Tough plastic is the safer pick, and you can skip the garden center entirely. A garbage can lid, a saucer sled, or an old frying pan all work.
Keep the water shallow: 1 inch at the edges and no more than 2 inches at the deepest point, with a gradual slope. Small birds need something to grip, so make the bottom rough with sand, a few rocks, or a branch sticking out.
The right setup also depends on your winters and on whether you can run power to the bath. The picker below narrows it down.
How to keep the water from freezing
If you have an outlet, heating is the easy route. A heated bath or a submersible heater needs power, and solar versions need sun. Thermostat-controlled de-icers turn on and off as needed, and many shut off if the bath goes dry.
No outlet? Use an unbreakable bowl. The routine is simple: put it out in the morning, bring it in when ice forms, and do it at the same time every day so birds learn when to show up.
Don’t add antifreeze or glycerin. To keep water liquid down to 15°F you’d need a 30 percent glycerin mix. It’s a low-level toxin, it raises a bird’s blood sugar, and it can mat feathers and cost them insulation.
If you use a heater, do the wiring right. Water and extension cords can electrocute someone, so put the heater on a GFCI circuit. The Electrical Safety Foundation calls a GFCI outdoors “a lifesaver, not a luxury”. A plug-in portable GFCI works if your outlet doesn’t have one. Use an outdoor-rated cord that matches the product, and call an electrician if you’re not sure.
Read the manual, too. K&H’s instructions for its de-icer say to use a grounded extension cord, keep the unit covered with water, and unplug it before you clean the bath.
Where to put it without endangering birds
A good rule of thumb: about 10 feet from the nearest shrub, in a spot that gets winter sun.
A bird at a bath is exposed, so it wants cover within a quick flight. But a shrub right next to the bath is where a cat waits. Advice runs from 10 to 15 feet from cover for a ground bath down to 5 to 10 feet from cat hiding spots, so about 10 feet lands in both ranges. If cats roam your yard, raise the bath 2 to 3 feet on a pedestal.
Sun keeps water liquid longer. Summer advice says shade, and in winter you want the reverse. Keep it out from under feeders too, where seed hulls and droppings land in the water.
Windows are the last piece, and feeder guidance conflicts. Bird Conservancy of the Rockies says within 3 feet of the glass or at least 30 feet away, while Birds Canada says within 10 feet. Go with the conservative version, and don’t count on any distance to prevent every collision. The real fix is marking the glass on the outside with decals.
Keeping birds safe and healthy
A winter birdbath adds a hazard the summer one doesn’t have. Wet feathers in freezing air can ice up, and a bird that can’t fly can’t dodge a cat or a hawk.
Plenty of birds bathe in frigid weather and shake off before the water freezes. Sometimes they don’t. There are reports of starlings dropping from the sky seconds after leaving heated baths, and mourning dove tails freezing to branches. A 2019 Star Tribune story tells of a Minnesota woman who found six cardinals in her yard that couldn’t fly. A wildlife rehabilitation center in Roseville told the paper bathing is dangerous in single digits or lower. None of that is a controlled study, but it’s reason enough not to leave a deep open pool out in a deep freeze.
The fix is to let birds drink without getting in. Lay a board, evergreen boughs, or wooden slats over part of the water, or use a nonmetallic grille with stones and sticks on top. Birds can reach the water with their bills, and they can’t soak.
Change the water daily if you can, and scrub the bath weekly with a stiff brush, mild soap, and water. Daily changes also stop mosquito larvae. In winter, dry air evaporates water fast, so top it off often, and clear algae when you see it.
If the water turns cloudy, moldy, or full of droppings, empty it and scrub. Then soak it in 1 part bleach to 9 parts water, rinse well, and let it dry. Dirty baths can spread diseases like trichomonosis and salmonella. Keep a dedicated brush, wear gloves, wash your hands afterward, and take baths down during an outbreak. Our piece on common backyard bird hazards has more.
What to do before the first freeze
- Swap ceramic or concrete for tough plastic, or use a lid, sled, or frying pan.
- Keep water 1 inch deep at the edges and 2 inches at most in the middle, with sand, rocks, or a branch for footing.
- Put it about 10 feet from the nearest shrub, in winter sun, and away from feeders.
- Plug a heater into a GFCI with an outdoor-rated cord, or plan the morning bowl swap.
- Add a board, grille, or stones if you get hard freezes.
- Wash the bath and set aside a brush for it. Use 1 part bleach to 9 parts water when it’s dirty.
Water is only one leg of winter survival. Birds also need food and cover, and Cornell’s K-12 program lists all three. Our guide to winter feeders makes the case for feeders, and the rest of our bird coverage is on the birds page.
Sources
- Penn State Extension, Water for Wildlife: Bird Baths and Backyard Ponds.
- Penn State Extension, Caring for Birds in the Winter.
- Cornell Lab of Ornithology and Project FeederWatch, Providing Water for Birds.
- Cornell Lab of Ornithology K-12, Bird Friendly Winter Gardens.
- Audubon, Winterize Your Yard for Birds.
- The Nature Conservancy, Should You Provide Birds Water in Winter?
- Star Tribune, Evidence that winter baths can be bad for birds, Val Cunningham, 2019.
- Stanford Birds, Drinking.
- Canadian Wildlife Health Cooperative, Backyard Birds health note.
- Birds Canada, Best Practices for Feeding Birds in North America.
- Electrical Safety Foundation, Outdoor Electrical Safety Check.
- K&H Pet Products, Super Ice Eliminator Bird Bath De-Icer.
- K&H Pet Products, Ice Eliminator instruction manual.