How do you find out what animals eat? Well, one way is to collect their poop. What goes in must come out, in one form or another. Before the rise of DNA techniques, the only way to analyze feces was by digging through it for recognizable bits of prey. Now all you need is for some DNA to make it through the digestive system and you can amplify it, compare it to a gene library, and figure out what species your animal of interest has been munching on.
Yesterday for ScienceNOW I wrote about a study on dolphin diet. The researchers compared DNA data from poop to data on the stomach contents of dead dolphins that were picked up through the Florida Marine Mammal Stranding Network. Find out what they learned.