'Given that hummingbirds are naturally attracted to the color red, many birdwatchers purchase or make red-dyed nectar mixtures,' says Marc Parnell, the author of The Birding Pro's Field Guides.
However, artificial dyes may carry a health risk, he says, and the same hummingbird-attracting result can be achieved by using clear nectar or sugar water with a red-colored hummingbird feeder.