Some birds are completely dependent on ants for their survival. These groups of ants are known as army ants and as the name would suggest they move in large packs (sometimes millions). When the move, they cause many animals to scurry to get out of their way. This, in turn, causes birds to prey on these small animals trying to get out of the way of ants.
What's even more interesting is that birds can be further categorized by how often they follow these ants. The first is only a casual follower of ants, meaning they will follow the ants as long as they stay within their territory. The second, regular followers will follow the ants out of their territory toward food. However, these birds still hunt for food themselves. The third, and most interesting, are those that completely depend on ants for their food, following them all over.
As one would suspect, these birds are most susceptible to changes in the ecosystem. For example, with threats like global warming and deforestation, this could wipe out a whole army of ants, leaving these birds with no way of getting food. It is interesting to note however, that these ants have been aiding birds in finding food as far back as prehistoric times.
Army ants are most commonly found Central and South America, Australia, Africa and Asia, however, some are even found in the US. These creatures do function much like an army in the way they work together. When they move through the forest at high speeds, they take out tarantulas, scorpions, roaches, beetles, grasshoppers, as well as lizards, frogs, even some small snakes (basically any small creature that gets in their way)! At night, when they rest, they link together and their span can be 3 feet wide.
Some birds that follow these army ants are Kingfishers, grosbeaks, woodpeckers, antbirds, antthrushes, antpittas, antshrikes, tanagers, toucans and robins.
Another interesting note is that termites play an important role as well in the bird's survival. For example, in the rainforests of South America, some birds like to make their nests in the termites' home, eating termites as they dig out the nest chamber. Not only do they like the termites' nest site, but ants can also be found here. These ants emit a strong scent overpowering the bird's scent. This discourages nighttime predators from raiding their nests.
It is fascinating to understand the relationship between these creatures. And that ants, who to most humans are annoying creatures, could be so vital to the survival of another species.