David Sloan Wilson

Tadpole Movie

Social foraging in American Toad (Bufo americanus) tadpoles

With my graduate student Charles Sontag and faculty colleague Stim Wilcox, I am studying social foraging in B. americanus tadpoles. These tadpoles rely heavily on information from other tadpoles to find food, as opposed to information from the food itself.

In this video clip, two food patches (fish food embedded in an agar-gelatin matrix) that differ in quality have been placed 15 cm apart on the right side of the screen. Within minutes tadpoles start streaming toward the patches and are differentially attracted to the better patch. They do not arrive from all directions but often in ‘columns’.

This video clip, which is played in fast motion, begins 23 minutes into the trial, after the best patch has been almost torn apart (and is therefore less distinct) than the worse patch. A column of tadpoles is streaming toward the patches along the shoreline (not all columns follow the shoreline). Notice that the tadpoles above the column are moving toward the column rather than directly toward the resource; this is especially apparent near the left edge of the screen.

About half way through the clip, the column becomes disorganized near the bottom center of the screen and the tadpoles to the left reverse their direction, heading away from the food patches. The fact that animals use each other to find food does not necessarily mean that they are cooperating.

The purpose of our research is to answer three major questions about social foraging:

1) The factors that determine the use of food information vs. social information

2) The factors that determine the degree of exploitation vs. cooperation

3) the factors that determine the use of cues (unavoidable byproducts of feeding behavior) vs. signals (designed to convey information) in social foraging.