FASTFACTS

AREA COVERED:

Up to 164 feet (50 meters)

HABITAT:

Tropical regions of Central and South America.

PREDATORS:

The ground cuckoo and other birds.

INDIVIDUAL HERD POPULATION:

Each colony includes from 300,000 to 700,000 ants.

ANTS IN-DEPTH

More from NationalGeographic.com

ARMY ANT (Eciton burchellii)

There are three genera of nomadic, swarming army ant species--Aenictinae and Dorylinae, which are found in the Eastern hemisphere, and the Western Hemisphere’s Ecitoninae, to which Eciton burchellii belongs. Army ants live primarily upon small creatures such as wasps, cockroaches, crickets and beetles, which they can subdue and carry back to their camp. They also may attack snakes, lizards and even nestling birds. Dozens of bird species, including the ground cuckoo, will steal army ants’ booty and sometimes eat them as well.

Unlike other migratory creatures who only travel once or twice annually, an army ant colony will migrate multiple times in a year in search of prey. They will build central nests and conduct foraging raids around them for two to three weeks, working in a starburst pattern to avoid covering the same ground twice. But after they exhaust their local hunting grounds, the colony’s population will abruptly pick up and go on a hunting march through new territory for another two or three weeks, moving in enormous columns 12 yards wide and the length of a soccer field. Along the way, the colony will create a series of bivouacs, or temporary shelters, fashioned by worker ants which stack their own bodies into a structure.

Despite being blind, army ants manage to move efficiently in such huge groups because of an intricate natural traffic management system. The ants form three lanes—a center lane moving toward the food source and two outer lanes moving back to the base. The ants’ behavior in the lanes follows what might appear to be a curious form of ant etiquette. Ants that are carrying pieces of food move in a straight line forward. When they bump into ants coming from the base who do not yet have food, those ants instinctively step out of the way.

Army ants’ hunting helps feed other species in the ecosystem. Beetles and mites live symbiotically in army ant colonies, and also live off the prey captured by army ants. The ants’ foraging missions also disturb small animals and cause them to flee their hiding places, which enables birds to catch and eat them.