Animal Communication

It would be difficult to imagine how dull, quiet and simply plain the world would be if animals did not communicate. The night sounds we remember from forest, field or pond; the colors by which we identify many animals; and the striking and sometimes bizarre movements and morphological features of courting animals –the peacock's train, the antlers of deer and elk, and the single greatly enlarged claw of male fiddler crabs—all are signals. In addition to the signals we can see or hear there are very many others that we cannot begin to perceive without special equipment to enhance our senses. These include the extraordinarily diverse chemical signals that insects (especially social insects) use to navigate and to regulate their societies; the electrical signals that some aquatic animals use to detect prey and communicate in dark and murky waters; and diverse and largely unstudied vibration or seismic signals used by animals as small as treehoppers and as large as elephants.

For over 70 years STRI researchers have been studying animal signals, their effects on receivers, and how patterns of communication govern the development and maintenance of animal social systems. Two of the stronger research traditions in animal communication at STRI are the study of animal courtship –including male auditory, visual and tactile signals and female responses to them—and the study of the signals insects use to establish social and reproductive dominance.

Perhaps because STRI researchers typically study animals in their natural habitats, they appreciate the profound effects the environment has on signaling systems. For example, the most sexually attractive calls that some male frogs produce also are most attractive to frog-eating bats. Competition among males for females has favored males who continue to use the attractive signal, but who fall mute on the slightest indication that a bat is foraging near by.

Predation also has shaped the courtship signaling of fiddler crabs. Males of some species make sand structures by their burrows where females come to mate. To find a suitable male and mating burrow, females must leave the safety of their own hole and expose themselves to attacks by shorebirds. Females are very attracted by the structures males build because they show the location of the burrow and allow them to run quickly and safely to it, even though they cannot see the burrow opening until they are very close. These examples show how predators, part of the "external" environment, influence animal communication.

STRI researchers working on social insects have discovered the critically important role of the social environment, including the prevailing signals, in determining the behavior of young as they grow and also their physical form (phenotype). The recognition that the phenotype both responds to and creates the environment that shapes it is one of the most fundamental results of STRI research in this field, with far-reaching consequences for the understanding of evolution.

 

Staff scientists researching Animal Communication