Ever wonder why some birds hop and some birds walk? Of course, there are many different kinds of birds, and we can't make a generalized statement like: small birds hop and big birds walk. Say something like that and the phone will ring right away.
Sand darters, for example, are pretty small, but they run instead of hop. Starlings are also small, but they walk. Notice, however, that no one is mentioning large birds that hop. Can you think of any? No? Well, that tells us something right there! Sure, large birds may hop a few paces, or hop while flapping their wings.
But unless you have a body like a kangaroo, the amount of energy needed to hop regularly when your mass is above a certain amount will be more than you can afford. Try hopping to work tomorrow instead of walking and see how long you can manage it. To put it bluntly, smaller birds have a choice that larger ones don't. But why hop in the first place? Tune in next time for the answer!