Washington, May 13 : Uppsala University researchers have found evidence that human vision is inadequate for research on bird vision.
The researchers insist that their finding means that the results of various studies that focussed on factors that influence sexual selection in birds need be re-evaluated.
"The results mean that many studies on sexual selection may need to be re-evaluated," says Anders Odeen, research assistant at the Department of Animal Ecology at the university, who carried out this study with his colleague Olle Hastad.
In a research article in the journal American Naturalist, the researchers say that the significance of birds' plumage-both in terms of richness of colour and particular signals-has been shown to be a major factor in birds' choice of partner.
However, they add, most studies are based on the hypothesis that human colour vision can be used to assess what birds see.
"It's a bit like a colour blind person describing the colours of clothes - it's often quite accurate but sometimes it can go badly wrong," says Odeen.
During the study, the Uppsala researchers used a mathematical model to investigate how bird and human retina work.
They combined the model with information on differences in the colour-sensitive cones of the eye, which enabled them to figure out how colour contrasts are perceived.
The researchers said that greater colour contrast could be translated as 'richness of colour' or more 'brightly coloured'.
"We show that the colours are perceived differently in over 39 percent of cases, which means that it is possible that more than one third of previous studies have been based on inaccurate information," they said.
According to the researchers, one of the reasons behind the differences was the fact that human vision cannot perceive UV light, while avian vision can.
The research team said that certain differences between how humans and birds perceive colours suggest that birds can clearly even those shades that are not perceived at all by humans.
Telling about the significance of their findings, the researchers said that they pointed towards the risk of making certain decisions on the basis of human vision, such as designing and legislating on lighting systems for domestic fowl.