September 25th, 2012
Natalie Angier on army ants and their parasites:
[Wherever...] there are army ants out on a hunting raid, peckish antbirds are almost sure to follow.
The birds are not foolish enough to try to eat them: Army ants are fiercely mandibled and militantly cohesive. Instead, they hope to skim off a percentage of the ants' labor, by snatching up any grasshoppers, beetles, spiders or small lizards that may jump to the side in a frantic attempt to elude the oncoming avalanche of predatory ants.
It's a gleeful reversal of the conventional notion of parasites as little, ticky things that plague large, poorly dressed hosts. Here the big vertebrates are the parasites, freeloading off insects a fraction of their size. [...]
Fun and frightening as the army ants are, the real stars are the birds. Angier explains that the antbirds' behaviour is in flux. Over time, as the populations of the various species of antbird fluctuate, scientists are observing how species are changing their behaviour in order to take advantage of the opportunities that open up. Fascinating stuff.
[Via The Awl]