Two winters ago I posted some suggestions for helping hummingbirds through winter weather, including boosting the sugar content of the feeder solution, taking advantage of heat radiating from windows, creating shelters, and using heat lamps. A lot of people are dealing with frozen feeders already this season, so here are a few more suggestions gleaned from the winter hummingbird community:
- Make a “feeder cozy” to help fresh solution retain its warmth longer. It can be as fancy as you like—knitted, crocheted, quilted, down-filled—but pipe insulation (fiberglass wrap or foam tube) or a section cut from a discarded blanket or sweater will do the job. If it’s roomy enough, you may even be able to tuck handwarmer packs inside. [A commenter on BirdForum mentioned using stockings; if your feeder bottle is small enough, a heavy wool sock would make a quick and easy cozy.]
- Wrap your feeder in outdoor-rated incandescent Christmas lights (the old style, not energy-efficient LEDs). The bulbs should produce enough heat to keep the sugar water slightly above air temperature, especially if you add an outer layer of aluminum foil to reflect heat and block wind.
- Wrap your feeder in pipe heating tape under a layer of insulation. Thermostatically controlled models will save energy by turning on as necessary to keep the solution just above freezing.
- Invert your sugars. The freezing point of a solution depends on the number of molecules present. More solute (sugar) molecules make it harder for the solvent (water) molecules to link up. Inverting your sugar, which breaks each sucrose molecule into one of fructose and one of glucose, doubles the number of molecules and depresses the freezing point by a few additional degrees without adding additional sugar.
To invert ordinary table sugar, combine 2 cups sugar with 1 cup water, adding 1/2 teaspoon lemon juice or 1/4 teaspoon cream of tartar to speed up the reaction. Heat the solution to a low boil on the stovetop in a heavy saucepan, washing down the sides of the pan with a little additional water to dissolve any stray sugar crystals. Use a candy thermometer to monitor the temperature, which will rise above the boiling point of water as the water in it boils away. Once it reaches 230° F., remove the pan from the heat and allow the syrup to cool, then pour it into a clean jar, pop on the lid, and store in the refrigerator. Substitute invert syrup for no more than half of the sugar in your feeder solution and reduce the water slightly (by about 2 tablespoons per cup) to compensate for the water in the syrup.
Safety first! Lights and heating tape present fire and electrocution hazards. Use only products that are rated for outdoor use, including extension cords. Do not use electric heating pads outdoors! Don’t enclose Christmas lights inside a cozy or place a cozy-covered feeder too close to a heat lamp—it could start a fire. Heat lamps or Christmas lights may melt the flimsy plastic of discount-store feeders.