 Some animals ' colours and patterns resemble a particular natural background . This is an important component of camouflage in all environments . For instance , tree @-@ dwelling parakeets are mainly green ; woodcocks of the forest floor are brown and speckled ; reedbed bitterns are streaked brown and buff ; in each case the animal 's coloration matches the hues of its habitat . Similarly , desert animals are almost all desert coloured in tones of sand , buff , ochre , and brownish grey , whether they are mammals like the gerbil or fennec fox , birds such as the desert lark or sandgrouse , or reptiles like the skink or horned viper . Military uniforms , too , generally resemble their backgrounds ; for example khaki uniforms are a muddy or dusty colour , originally chosen for service in South Asia . Many moths show industrial melanism , including the peppered moth which has coloration that blends in with tree bark . The coloration of these insects evolved between 1860 and 1940 to match the changing colour of the tree trunks on which they rest , from pale and mottled to almost black in polluted areas . This is taken by zoologists as evidence that camouflage is influenced by natural selection , as well as demonstrating that it changes where necessary to resemble the local background . 
