depends on the bird
hawks eagles crows storks owls ducks geese woodpeckers pelicans penguins parrots parakeets canaries swans sea gulls pigeons blue jays puffins humming birds chickadees egrets finches sugar birds bee...
Because all birds live in different environments and weather conditions. ------------------------------------------------------------------------------------- Birds feathers have evolved to serve a...
eagle hawk woodpecker thrush raven robin starling crow sparrow dove pigeon penguin heron flamingo toucan blackbird wood pigeon falcon parrot puffin budgie canary magpie sparrow pheasant hornbill owl...
swine flu
Because, there are different types of birds and generations that look different depending on what family the bird comes from.