 Nearly 5 @,@ 000 species of louse have been identified , about 4 @,@ 000 being parasitic on birds and 800 on mammals . Lice are present on every continent in all the habitats that their host animals and birds occupy . They are found even in the Antarctic , where penguins carry 15 species of lice ( in the genera <unk> and <unk> ) . 
