The Wild Bird Shop of Cannon Beach, Oregon publishes a recipe for hummingbird syrup on its website at WildBirdShop.com. The recipe mimics flower nectar and consists of just table sugar and water. The sugar water mixture is heated to dissolve the sugar, remove chlorine, and kill mold and yeast spores.
To make hummingbird syrup, mix 4 parts water to 1 part table sugar in a pan. Use only cane sugar. Do not use honey, Jell-O, raw sugar, corn syrup or brown sugar. Also, do not use turbinado sugar or molasses. Avoid using red food coloring as it is not necessary and is potentially harmful to hummingbirds.
Bring the sugar water to a boil, and take the pot off the heat. Stir until all the sugar is dissolved. Don't boil for too long as the ratio of water to sugar changes as water evaporates. Boiling the syrup rids the water of chlorine and kills any bacteria that could spoil the syrup and harm hummingbirds. Boiling the syrup also improves its shelf life.
Before filling a bird feeder or storage container with the syrup, cover the pot, and allow the syrup to cool down. Extra syrup can be stored in a refrigerator.