Two different questions get answered as one every winter, and they have different answers. The first is whether birds need open water in freezing weather. The second is how to keep a bath liquid if you decide to provide it.
We are going to take them in that order, because the two most authoritative sources in American backyard birding do not agree on the first one, and that is worth knowing before you buy anything.
Do birds actually need it
The Cornell Lab of Ornithology is the more cautious of the two: "Birds will come to birdbaths year-round. Fortunately, keeping a birdbath ice-free in winter is not critical. Birds have several physiological mechanisms for conserving water, and can usually get what they need from snow or dripping icicles."
The National Audubon Society reads differently. Their winter guidance states plainly that "many kinds of birds bathe in and drink from open water in frigid weather," and goes on to recommend buying a heated bath or converting an existing one, with no equivalent caveat. University of Nebraska Lincoln Extension is firmer still: "A fresh, unfrozen water source is as important to birds in the fall and winter as other seasons."
That is not a factual contradiction so much as a difference in framing, and we would rather show it than pick one. Our own reading is that winter water is a good thing to provide and not a rescue mission. If you enjoy the birds it brings, run it. If you are away for three weeks in January, Cornell is telling you that the birds will be fine.
The part with no disagreement at all: put nothing in the water
Every source lines up here, and the wording is unusually blunt for organizations that normally hedge.
- Antifreeze
- Cornell says to "never add antifreeze to a birdbath" and states that it "is poisonous to all animals, including birds." This is the one that kills.
- Glycerin
- the folk remedy that circulates every December. Cornell: "Don't use glycerin, either: it can saturate and mat a bird's feathers leaving it susceptible to hypothermia." Project FeederWatch adds a second mechanism: "Glycerin is a low-level toxin and has a sweet taste. Ingesting large amounts of glycerin elevates the blood sugar level of a bird, which can be harmful or even fatal."
- Salt
- we looked for a bird organization or extension service that addresses salt in bath water specifically and did not find one. What we found instead was guidance about salting walkways, which is a different question. So we cannot cite anyone on this. We would not do it, on the general principle that a bath is drinking water, but that is our position rather than a sourced one.
Read the glycerin warnings together, because they are the interesting pair. One is about ingestion and one is about the feathers. A bird that gets glycerin in its plumage loses the insulation that keeps it alive at the exact temperature you were trying to help it survive. The remedy makes the problem worse in the specific case it was meant for.
Choose a suitable bird bath heater
If you want to provide water during freezing weather, use a heated bird bath or a de-icer confirmed as suitable for the basin material, size and water depth. Check the required water level and operating instructions. Do not assume every plastic or resin bowl, or every floating de-icer, is suitable.
Estimate the running cost
Running cost depends on the heater’s wattage, operating time and your electricity rate. Estimate it as: watts ÷ 1,000 × operating hours × price per kWh. A thermostat may reduce operating time, but the heater can run for long periods in sustained cold. Use your own electricity rate rather than a fixed seasonal estimate.
Power connection and handling
Use a suitable outdoor outlet with GFCI protection. Follow the heater’s cord requirements; some models prohibit extension cords. Do not use an extension cord as permanent wiring. Keep electrical connections dry and protected from weather, and unplug the heater before handling it or cleaning the bath.
Protect our concrete bird baths during hard freezes
Winter care depends on freezing conditions in your area. Before hard freezes, we recommend draining and drying our concrete bird baths and storing them in a sheltered, dry place. If the bath stays outside, prevent rain and snow from collecting in it. A heater may keep water open, but it does not guarantee protection against freeze damage.
Drain and clean the bath, then let it dry before storage. Move a removable bowl only if it can be handled safely. Do not turn a bowl upside down on its pedestal unless it is designed to sit securely that way. If the bath remains outdoors, secure a suitable cover, prevent water from pooling on it and check underneath after rain or snow.
Our winter care guide for concrete bird baths covers seasonal care. Read more about preventing freeze damage and cleaning a concrete bird bath.
Browse our concrete bird baths and plan winter care for your local conditions.
Provide water without electricity
Without electricity, we recommend offering fresh water in a separate shallow dish that you can bring indoors when ice forms. Sun and shelter may delay freezing, but a floating ball, dark stones or moving water cannot reliably prevent freezing during sustained cold. Check the dish regularly rather than relying on a once-a-day refill.
If a concrete bowl has frozen
If our concrete bird bath freezes, do not hit the ice or pour hot water into the frozen bowl. Let it thaw gradually, then drain and dry it. While you wait, provide fresh water in a separate shallow dish.
Things that do not change in winter
- Depth
- no source we found gives a different winter figure. Cornell's 1 inch at the edges and 2 inches maximum in the middle is stated as general guidance and repeats in winter contexts. If depth is new to you, it is check one in our guide to why birds are not using a bird bath.
- Placement near cover
- Audubon: "Make sure there's ample water near protective shrubs." The same trade between open sightlines and escape cover applies in January.
- Cleaning
- a frozen bath still accumulates droppings and debris between thaws. The routine is in our guide to keeping bird bath water fresh.
One thing we could not answer
People ask whether a de-icer warms the water or merely stops it freezing, and whether warm water is bad for birds in cold weather. We could not find a statement on either question from any source we would cite. Thermostatically controlled is the phrase Cornell uses, which implies the unit is holding a set point rather than heating without limit, but that is us reading a word rather than a source answering the question. If you know of a published answer we would like to see it.
Frequently asked questions
How do I keep my bird bath from freezing?
If you want to provide water during freezing weather, use a heated bird bath or a de-icer confirmed as suitable for the basin material, size and water depth. Check the required water level and operating instructions. Do not assume every plastic or resin bowl, or every floating de-icer, is suitable. Without electricity, offer water in a separate shallow dish and bring it indoors when ice forms.
Can I put antifreeze or glycerin in a bird bath?
No. Cornell says to never add antifreeze and states it is poisonous to all animals including birds, and warns that glycerin "can saturate and mat a bird's feathers leaving it susceptible to hypothermia." Project FeederWatch adds that ingesting glycerin raises a bird's blood sugar and can be fatal.
Do birds need water in winter?
The sources differ in emphasis. Cornell says keeping a bath ice-free in winter "is not critical" because birds can usually get what they need from snow or dripping icicles. Audubon says many kinds of birds bathe in and drink from open water in frigid weather, and recommends a heated bath. Both are worth reading before you decide.
Can I leave a concrete bird bath out in winter with a heater?
Winter care depends on freezing conditions in your area. Before hard freezes, we recommend draining and drying our concrete bird baths and storing them in a sheltered, dry place. If the bath stays outside, prevent rain and snow from collecting in it. A heater may keep water open, but it does not guarantee protection against freeze damage.
How much does a bird bath heater cost to run?
Running cost depends on the heater’s wattage, operating time and your electricity rate. Estimate it as: watts ÷ 1,000 × operating hours × price per kWh. A thermostat may reduce operating time, but the heater can run for long periods in sustained cold. Use your own electricity rate rather than a fixed seasonal estimate.
Is an extension cord safe for a bird bath heater?
Use a suitable outdoor outlet with GFCI protection. Follow the heater’s cord requirements; some models prohibit extension cords. Do not use an extension cord as permanent wiring. Keep electrical connections dry and protected from weather, and unplug the heater before handling it or cleaning the bath.
References
- Reference: Attract Birds With Birdbaths | The Cornell Lab of Ornithology, All About Birds
- Reference: Providing Water for Birds | Project FeederWatch, The Cornell Lab of Ornithology
- Reference: Winterize Your Yard for Birds | National Audubon Society
- Reference: How to Provide Water for Birds and Butterflies | Audubon Rockies
- Reference: Feeding Birds in Winter | University of Nebraska Lincoln Extension, Lancaster County
- Reference: Electrical Safety | National Fire Protection Association
- Reference: Extension Cords | United States Consumer Product Safety Commission
- Reference: Electricity Monthly Update, End Use | United States Energy Information Administration