Bird Energy, Land or water?

Question

Birds migrate every year , and they fly very long distances, now,Ornithologists believe that flying over water requires more engery, and Flying over land is less engery. now can anyone explain this alittle further, or even tell me why birds still fly over water still

Answer 1

Flying over land, allows a bird to stop and rest.  They cannot stop when flying over water so therefore they need to store up enough energy and fat to get them over oceans.  Flying over oceans is the most dangerous part of a birds migration...many die at sea.  Most birds will fly over the oceann at night when they will have a lesser chance of becoming dehydrated (during the heat of the day).  Many times flying over the ocean is the quickest way or the only way to their destination so they will not or cannot avoid it.

Answer 2

land tends to be less windy so its easier to fly.

flying a to b in a straight line is quicker, if that means over water then thats why the fly that way.