Birds see a totally different world from what we are familiar with, and now we can find a hint of what appears to be, thanks to the specially designed camera that simulates bird's eye view.
As well as being fascinating, the resulting images also explain why birds can orient themselves so precisely through dense foliage.
Behavioral biologist Cynthia Tedor, formerly from Lund University in Sweden, explains that the team wanted to look for patterns in nature, but scientists have not yet thought of looking.
They chose to study birds' vision because the birds are very visually oriented – they use their eyesight for feed and hunt for food ̵
To find out how these violet and UV-sensitive cones are translate visually, researchers are filming densely forest habitats in Sweden and Australia, a multi-spectral camera with specially designed filters to mimic what the bird can see.
 Normal photo, left. A photo that includes green light and UV colors. Multispectral images clearly show how UV sensitivity detects greater contrast between the top and bottom surfaces of the leaves, making the position and orientation of each sheet in a very clear, 3D way. "What appears to be a green mess for humans is clear leaflets for birds, and no one knew about this study," said biologist Dan-Eric Nilsson, also from Lund University. Both the top and bottom surfaces of the leaves reflect similar levels of ultraviolet light, so the researchers believe that the differences are due to how many UV rays reflect the transmission.
UV light reflects the leaves more than 25 times
By comparison, our eyes can not understand the difference because the green light is transmitted and reflects around the same amount, creating much less contrast when viewed through green frequencies.
[UV vision] probably helps birds fly and jump through dense foliage with greater flexibility, "said Tedor to ScienceAlert
" Many birds are looking for insects and spiders to hide the lower surfaces of the leaves and can quickly define these surfaces. Using computer modeling, Nilsson and Tedor also worked out that maximum leaf contrast is observed in short UV wavelengths in well-lit, open shadows and longer UV hs in closed low-light shadows. This may explain why the fourth color birds find varies.
Of course, what we see in the visualized UV images is just a bird's eye simulation because our eyes unfortunately do not fully fit the task. "Since the birds have four classes of cone (red, green, blue and UV) and we only have three (red, green, blue), we can only visualize three of the cone canals of the birds at the same time, Tedor. explains. "It is impossible for us to generate a realistic representation of how the four-cone channel could look."
But even if we can not see these extra colors on our own, we can still use super-colored birds
"The enhanced 3D structure in UV can be visualized by remote or autonomous vehicles to help them "They want to move in complex forest environments without entanglement in the leaves," says Tedor.
Seeing in four colors sounds, it probably comes with some flaws.
"One disadvantage of the fourth-class cone is that it occupies a place in the retina that could be occupied by more than the other three cone classes," Tedor says. "This may have a detrimental effect on resolution and sensitivity in low light conditions."
Tedor says the next step in understanding birds' vision will be to see how their sources of nutrients are displayed in UV. And they could also explore how birds see different species and environments.
"We may have the idea that what we see is a reality, but it is a very human reality, and other animals live in other realities, and we can now see through their eyes and reveal many secrets." The reality is in the eyes of the observer, "concludes Nilsson
Their document was published in Nature Communications