These tiniest creatures on planets need to be extra careful in the cruel world out there. Like any other bird, they need to build a nest, survey their surroundings for any threats, mate, etc.
Given their small size they need to have some ability that could give them a competitive edge over their rivals. A recent study, “Wild hummingbirds discriminate nonspectral colors” suggests that broad-tailed hummingbirds are capable of visualizing colors that are beyond the visible spectrum of humans.
Cones and rods cells in an eye are capable of taking in and processing the light to form a visual in the brain. Rods are concerned with the intensity of light while cones are responsible for differentiating between the colors. There are three different kinds of cones in a human eye, each responsible for recognizing each of the three primary colors, blue, red, and green.
While humans only have three cones in their eyes, birds possess four of them. This makes them capable of intercepting colors that lie outside the visible spectrum.
An experiment was conducted on Selasphorus platycercus to see if they could distinguish between spectral colors and spectral colors combined with UV. Humans are unable to see the UV light. If the birds were successful in differentiating between the two lights, they were rewarded with sugar treats. It was seen that the birds were able to distinguish between two kinds of lights making them capable of visualizing colors that lie outside the visible light spectrum.
While humans don’t need to see colors lying outside the visible light spectrum, the extra cones in the birds’ eyes are quite useful as certain plants reflect the light off unusual pigments.
Another experiment was conducted using the plant samples that these birds land on. It was seen that 35% of those plant colors could not be seen by humans.
Hence its proven that the hummingbirds found in the backyards are seeing a totally different world than humans.
The study, “Wild hummingbirds discriminate nonspectral colors”, was authored by Mary C. Stoddard, Harold N. Eyster, Benedict G. Hogan, Dylan H. Morris, Edward R. Soucy, and David W. Inouye