Some African birds follow nomadic ants to their next meal

COIMBATORE, India — To better understand Equatorial Guinea’s tropical birds, ornithologists Luke L. Powell and Patricia Rodrigues scan the ground rather than the trees. They are searching for nests of driver ants (Dorylus spp.). These voracious predators will march out of their underground nests and fan out into a meters-wide swarm, flushing out insects and worms from undergrowth. From the trees, birds swoop down to catch the fleeing insects. And where the ant swarms go, the birds follow.

Swarms make humming and “tick tick tick” sounds, says Powell, of the University of Porto in Portugal. It is the sound of the ants — and of animals scurrying in panic (SN: 8/12/02). “Then you hear the sounds of birds chirping at the edge [of the swarm], communicating.”