The bright red color of hummingbird feeders is based on a complex mix of biological fact and evolutionary history. This article explores why these tiny birds are drawn to red and how that preference is incorporated into feeder design. It also addresses a common mistake regarding the safety of the liquid nectar.
How Hummingbirds Perceive Color
The intense attraction hummingbirds show toward red is rooted in their biology, specifically their vision. Unlike humans, who have three types of color-sensitive cone cells, hummingbirds are tetrachromatic, possessing four types of cones. This extra cone is sensitive to ultraviolet (UV) light, which vastly expands their color perception beyond the human visible spectrum.
This unique visual system allows them to see colors humans cannot, including combinations like ultraviolet-plus-red and ultraviolet-plus-green. The dense concentration of cones in their retina gives them a heightened sensitivity to the warmer end of the spectrum. This makes saturated colors like red and yellow stand out vividly, helping them efficiently spot high-energy food sources against green foliage.
The red coloration on a feeder is intensely conspicuous to a hummingbird, serving as a powerful visual cue. This biological wiring means a bright red object immediately registers as a potential source of the high-octane fuel they constantly need. Hummingbirds are fast learners and quickly associate a specific color with a nectar reward, reinforcing their focus on highly visible, sweet sources.
The Design Link to Natural Nectar Sources
The strong visual preference for red is a result of millions of years of co-evolution between hummingbirds and certain flowering plants. Numerous plant species rely on hummingbirds for pollination and have evolved specific traits to attract only them. These bird-pollinated flowers, known as ornithophilous flowers, are often red or orange and tubular in shape.
This coloration serves a dual purpose in nature. It acts as an unmistakable signal to hummingbirds while simultaneously discouraging most insect pollinators, such as bees, which struggle to perceive true red. By using red, the plant ensures the hummingbird, an effective pollinator, receives the nectar reward and carries the pollen to the next flower.
The red plastic and accents on modern feeders mimic this successful natural strategy. Feeder manufacturers leverage the bird’s innate and learned association that red signals a generous, high-energy nectar source. This mimicry effectively catches the attention of a passing bird and guides it to the artificial food supply.
Why Red Dye Should Be Avoided
While the red structural parts of the feeder are a safe attractant, adding red dye to the liquid nectar itself is unnecessary and potentially harmful. The red plastic is sufficient to draw the birds in, as they quickly learn that the clear liquid inside provides the sugar reward.
Commercial nectars often contain artificial coloring agents like Red Dye No. 40, a petroleum-based substance. Although approved for human consumption, a hummingbird’s tiny body size and extremely high metabolism mean they consume it in highly concentrated doses. A small hummingbird can ingest the dye at levels up to 17 times the recommended acceptable daily intake for a human, relative to body weight.
There is no definitive scientific study proving the dye’s toxicity specifically to hummingbirds. However, wildlife rehabilitators report anecdotal concerns regarding higher mortality and tumors in birds fed dyed nectar. Because the dye offers no nutritional value, the best practice is to offer a simple solution of one part refined white sugar mixed with four parts water.