http://www.signonsandiego.com/news/world/20050428-1231-explodingtoads.html

It would appear that the crows are the culprits. At least it is the best theory so far.

One German scientist studying the splattered amphibian remains has a theory: Hungry crows are pecking out their livers.

"The crows are clever," said Frank Mutschmann, a Berlin veterinarian who collected and tested specimens at the Hamburg pond. "They learn quickly from watching other crows how to get the livers."

Based on the wounds, Mutschmann said, it appears that a bird pecks into the toad with its beak between the amphibian's chest and abdominal cavity, and the toad puffs itself up as a natural defense mechanism.

But, because the liver is missing and there's a hole in the toad's body, the blood vessels and lungs burst and the other organs ooze out, he said.