Direct species interactions are the main connectors between species in a community, but their effects on the species involved are not always obvious. In this figure set, students use a study by Wrege et al. (2005) to examine the relationship between the army ant Eciton burchellii and birds that follow foraging swarms.

Army ant swarms are one of the most dramatic sights in tropical forests and observers are impressed by the array of species that follow these swarms. It has long been assumed that some bird species have a mutualistic relationship with army ants because these birds often follow swarms and catch animals escaping from the advancing ants. It was further assumed that the birds chased some escaping animals back toward the swarm. Like many apparent mutualisms, the true effects of the ant-following birds on the ants had never been closely examined.

In this issue, the students will design a hypothetical experiment to measure the effect of birds on army ant foraging success, interpret the results of a real experiment, and consider the consequences of the interaction on the ant colony and the forest community.

References

• Gotwald, W. H., Jr. 1995. Army Ants: The Biology of Social Predation. Cornell University Press, Ithaca, NY.
• Schneirla, T. C. 1971. Army Ants: A Study of Social Organization. W. H. Freeman and Company, San Francisco, CA.
• Willis, E. O., and Y. Oniki. 1978. Birds and Army Ants. Annual Review of Ecology and Systematics 9:243-263.
• Wrege, P. H., M. Wikelski, J. T. Mandel, T. Rassweiler, and I. D. Couzin. 2005. Antbirds parasitize foraging army ants. Ecology 86:555-559.