I Love Birds, All Birds

I think birds are beautiful. I am amazed at how they survive at all. Where I live some of the birds are with us all year. Like sparrows and blackbirds and robins. And buzzards and red kites. Some I hear and never see like the owls. Recently I have seen a yellow wagtail every time I get to the road at the end of the farm track. Then we have summer visitors, especially the martens but they have gone back to Africe. How does such a small creature fly that far?