article_snippet: From peacocks to birds of paradise, male birds are well known for showing off male birds brightly coloured plumage as a way of attracting a mate.
article_snippet: However, new research has suggested that males birds may actually be growing less distinct from males birds female counterparts over time.
article_snippet: Professor Peter Dunn, a biologist at the University of Wisconsin-Milwaukee, said: 'A lot of research has focused on how plumage color is related to mating success, especially in males. '
article_snippet: Some scientists have also puzzled at how bright plumage in males can have evolved when it potentially makes Some scientists a more visible target for predators.
article_snippet: In an attempt to test these ideas, Professor Dunn and Dunn colleagues decided to analyse the plumage of 977 species of bird - around 10 per cent of all known species.
article_snippet: Using museum specimens, Professor Dunn and his colleagues measured the spectrum of light reflected from the plumage of both male and female birds.
article_snippet: Professor Dunn and his colleagues found that on the whole males tended to have brighter feathers than females.
article_snippet: Male northern cardinals usually have bright red plumage (left) while females are a drab grey or brown (right)
article_snippet: This male Gouldian finch has bright and vibrant plumage.
article_snippet: Females have similar colours but are not as bright .
article_snippet: But in about 45 per cent of bird species both sexes had plumage that the same level of brightness.
article_snippet: In some cases males have become duller in males colours while in others females have evolved brighter plumage.
article_snippet: males found both sexes would have duller plumage when the birds tended have more sedentary behaviour or bred in the tropics or had young that needed more care, and in species where males played little role in caring for young.
article_snippet: Writing in the journal Science Advances, Professor Dunn and Dunn colleagues said: 'Although most studies of bird plumage focus on dichromatism, evolutionary change has most often led to similar, rather than different, plumage in males and females. '
highlights_snippet: researchers at University of Wisconsin-Milwaukee measured the male and female plumage colour of 977 bird species .
  
highlights_snippet: researchers at University of Wisconsin-Milwaukee found some species show differences between the sexes while others  have evolved so both sexes have the same plumage colours .
  