I saw the same video in YouTube. It is amazing to see a congregation of Ruby Throated hummy at the coast before migrating over the Gulf of Mexico to SA. I am not sure what geological factors limit only one species of hummy found east of the Rocky whereas multiple species are found throughout the west.
Another interesting fact is that humming bird are found only in the new world, whereas biologically equivalent Sun Bird that share the same diet, habitat and body design are found throughout the old world with no overlapping. Attached is a video I took in the Hong Kong Bird market in which the first cage bird is a sun bird that looks remarkably like a hummy. The second bird is a South American finch, Green Singer, that sings like House Finch in my backyard. I am not sure what species of birds are in the third and forth video clips except that they are SE Asian bird.
