Why do hummingbirds prefer red flowers? June 03 2014
We've all been trained to think of red flowers and feeders to attract hummingbirds. The reason that hummingbirds tend to feed from red flowers is two-fold (at least), and another amazing example of how nature provides different things to different plants, animals, and insects.
Hummingbirds can see all colors, and can actually see near UV (meaning beyond violet in the spectrum of light, remember your "ROY G BIV" from school with the order of the light spectrum colors?). So this is why the colors on the ends of the spectrum like red, orange, and violet stand out more to hummingbirds than other animals.
Another contributing factor to hummingbird's preference for these colors is that they are hard for bees and other pollinating insects to see. Bees, wasps, and other pollinating insects prefer yellow flowers. Thus they may contain more nectar due to a lack of competition as a food resource. If you have a hummingbird feeder with yellow feeding ports or yellow on them, either remove the yellow or paint them red to help keep the bees away. And if the bees have learned that your hummingbird feeder is a great source for nectar (regardless of color), consider using bee-proof ports (like the bee-proof Flower Feeding Tubes for Parasol feeders).
Additionally, hummingbirds prefer nectar that is 15-25% sucrose that is typically produced by hummingbird-pollinated flowers versus those that are bee- and insect-pollinated, which contain nectar made from fructose and glucose (sugars preferred by insects). This is why the ingredients for hummingbird nectar are water and sugar in a 4:1 ratio (for approximately 21% sucrose content).