Here is a small selection of photographs showing various species of animals gather in some kind of swarms. There might be different reasons for that, from creating colonies to the familiar to all of us migration.
On these pictures you will see hundreds, thousands, and maybe even millions of living creatures that gather for migration in search of a new habitat or food. Or there might as well be pictures showing the birth of a new colony. Some of these gathering cannot be explained not only by photographer but by researchers also.