24 January 2006

(87) The Death Pool

Hungry crows fingered in enigma of exploding toads

Saturday, Apr 30, 2005

Why are toads puffing up and spontaneously exploding in northern Europe?

It began in a posh German neighbourhood and has spread across the border into Denmark. It has left onlookers baffled, but one German scientist studying the splattered amphibian remains now has a theory: Hungry crows may be 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."

So far, more than 1,000 toad corpses have been found at a pond in Hamburg and in Denmark. But the pond water in Hamburg has been tested, and its quality is no better or worse than elsewhere in the city. The remains have been checked for a virus or bacteria, but none has been found.

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 organs ooze out.

As gruesome as it sounds, it isn't actually that unusual, he said.

"It's not unique -- it's in a city area, and that makes it spectacular," he said. "Of course, it's something very dramatic."

There have also been reports of exploded toads in a pond near Laasby in Denmark.

Local environmental workers in Hamburg have described it as a scene out of a horror or science fiction movie, with the bloated frogs agonizing and twitching for several minutes, inflating like a balloon before suddenly bursting.

"It's horrible," biologist Heidi Mayerhoefer was quoted as telling the Hamburger Morgenpost daily. "The toads burst, the entrails slide out. But the animal isn't immediately dead -- they keep struggling for several minutes."

Hamburg's Institute for Hygiene and the Environment regularly tests water quality in the city, and found no evidence that the toads were diseased. The institute even ruled out that the toads were suffering because of a fungus brought in from South America.

Other theories have been that horses on a nearby track infected them with a virus, or even that the toads are taking the selfless way out -- sacrificing themselves by suicide to save others from overpopulation.

Could hungry crows be a reasonable answer?

"We haven't seen that. It might be, it might not be," institute spokeswoman Janne Kloepper said.

Late last week, the Pond of Death remained cordoned off, festooned with "Keep Out" signs. "We are still not one 100 per cent sure of the cause," said Heidi Mayerhoefer, who is co-ordinating the toad investigation for the city authorities.
She said that only one other instance of exploding amphibians had been recorded in Germany. In the eastern state of Brandenburg, a smaller outbreak occurred in the early 1990s which was attributed to hungry birds.

Should the bird theory prove true, it will doubtless heighten Hamburg residents' anxieties about the feathered creatures. Two years ago, the city's crows gained notoriety after they mysteriously attacked joggers, Hitchcock-style, in a Hamburg park without warning. In the worst incident, about 20 crows "dive-bombed" passers-by, sending one woman screaming from the park with birds clinging to her hair, pecking at her face and ears. As with the toads, the cause remains a mystery.

Local officials in Hamburg were advising residents to stay away from the pond dubbed "the death pool" by German tabloids.


Mystery of exploding toads solved

May 9, 2005

Germany's great exploding toads mystery has been solved: They were gruesomely murdered by crows with a taste for foie gras.

Health officials in Hamburg started to panic after some 1000 toads puffed up and exploded last month, their entrails splattering an area of up to a square metre.

But now one of Germany's top experts on amphibians says he's cracked the case. Frank Mutschmann found all had identical circular incisions on their backs - and their livers were missing.

"It was clearly the work of crows, which are clever enough to know the toad's skin is toxic and realise the liver is the only part worth eating," he said. "Only once the liver is gone does the toad realise it's been attacked. It puffs itself up as a natural defence mechanism.

"But since it doesn't have a diaphragm or ribs, without the liver there is nothing to hold the rest of its organs in. The lungs stretch out of all proportion and rip; the rest of the organs simply expel themselves."