Måns Andersson, who directs the research team said, "More and more evidence indicates that the most changeable part of the environment consists of parasites, bacteria and viruses. All of these, especially viruses, evolve more rapidly than the hosts whose resources they live off of. The host will therefore always be in an important evolutionary race against its diseases. Thus it seems that the female uses the forehead spot as a health indicator. When she chooses males with a large forehead spots, she takes not only the healthiest males but also the ones with the best immune defence against future virus infections."
The male collared flycatcher can change the size of the forehead spot during the mating season and that males that unfurl their forehead spots most are those that produce the most antibodies informs the study.
So beauty is the secret to be safe from Bird flu.