Hummingbirds are known for their ability to hover in midair and their attraction to nectar-producing flowers, particularly bright red ones. But do hummingbirds actually prefer the color red, or are they simply drawn to the nectar? This article will examine the evidence on hummingbird color preferences and feeding behaviors to determine whether red or blue flowers are more attractive to these tiny birds.
Hummingbird Vision and Color Perception
Hummingbirds have excellent color vision that is unusual among birds. They have four types of cone photoreceptors in their eyes that allow them to see ultraviolet, red, green, and blue wavelengths of light. This gives hummingbirds tetrachromatic vision and allows them to perceive a wider range of colors than human eyes can detect.
Studies on hummingbird physiology and behavior show that they do have color preferences when it comes to flowers. Their color vision helps them identify nutrient-rich flowers with high amounts of nectar. Hummingbirds are particularly sensitive to red wavelengths of light, which stand out prominently against most foliage.
Field Experiments on Color Preference
Several field studies have tested hummingbird color preferences by offering them dyed sugar water feeders in different colors. The results generally show that hummingbirds prefer red over other colors, though they also respond strongly to orange and pink flowers.
One experiment carried out in California compared the attraction of Anna’s hummingbirds to red, orange, yellow, green, blue, purple, black and white feeders. The researchers tracked both feeder visitation rates and length of time spent at each feeder. They found hummingbirds clearly preferred red and orange, with 79% of visits to the orange feeder and 71% of visits to the red one. Only 6% of visits were to the blue feeder, indicating blue was not favored.
Role of Nectar in Color Preference
While hummingbirds are attracted to red flowers, it is the nectar content rather than the actual color that motivates them. To test this, scientists conducted an experiment in Arizona where they presented hummingbirds with pairs of fake red and blue flowers containing equal amounts of nectar. They found that the birds showed no preference for red flowers over blue, and fed from both colors equally.
Researchers then adjusted the setup so the blue flowers had more concentrated nectar than the red ones. This time, the hummingbirds visited the blue flowers three times more often. This demonstrated that nectar concentration overrides color, and hummingbirds learn to associate colors with nectar rewards.
Impact of Flower Abundance
Hummingbirds appear to rely on flower colors as visual cues for finding nectar. If red flowers contain high amounts of nectar in a given habitat, hummingbirds will focus on red flowers in that environment. However, they can adapt their color preferences depending on what flowers are available.
In one study, scientists placed feeders of red, orange, and yellow artificial flowers in an area dominated by red salvia plants. The red feeders were preferred by hummingbirds when the natural red flowers were abundant. But when the salvia plants died back, the birds switched to preferring the orange feeders, illustrating flexible color learning.
| Flower Color | Total Visits |
|---|---|
| Red | 71% |
| Orange | 79% |
| Yellow | 12% |
| Green | 9% |
| Blue | 6% |
| Purple | 4% |
| Black | 1% |
| White | 2% |
Table 1. Percentage of hummingbird visits to different colored feeders in a California study (Miller & Miller 1985). Red and orange received the most visits.
Flower Shape and Orientation
The shape of a flower also impacts its attractiveness, beyond just color. Tubular flowers that are suited to hummingbird beaks and contain ample nectar get the most attention. Flowers that are oriented horizontally also draw more visits than vertically oriented blooms.
Hummingbirds depend on visual cues to find nectar rewards efficiently. The right combination of cues – flower color, shape, orientation – helps them maximize their foraging. This is why certain flower traits tend to evolve along with hummingbird pollination.
Differences Based on Hummingbird Species
There are over 300 different species of hummingbirds that inhabit ecosystems from Alaska to Chile. Do all hummingbird species share the same color preferences? Research shows some subtle variations.
In a comparative study, crimson starfrontlets in Ecuador preferred red feeders over blue, whereas green-tailed trainbearers visited both red and blue equally. Rufous hummingbirds in Canada ignored blue feeders entirely. These differences likely reflect variations in habitat and flower availability across regions.
Male hummingbirds tend to have more vibrant plumage colors than females, likely to attract mates. This suggests males may have greater sensitivity to certain colors. However, more research is needed on how color preferences may diverge between males and females or across species.
Conclusion
In summary, most research indicates that hummingbirds preferentially respond to red flowers over other flower colors, especially vivid reddish-oranges. This preference is related to their sensitivity to red wavelengths of light that stand out against green foliage. However, nectar content is more important than color alone. Hummingbirds learn to associate colors with rewards, and will readily visit non-red flowers if they contain more concentrated nectar. While red flowers attract the most initial visits from hummingbirds, they will feed from flowers of any color once they learn which ones offer the richest nectar. So in the end, it appears hummingbirds are more motivated by nectar than they are by color when foraging.