This Japanese squirrel appears to be feeding on a poisonous toadstool with ease. This not only helps the rodent to survive, the fungus could also have an advantage.
Eating fly agarics or the closely related panther mushrooms can be deadly. This is because these mushrooms contain the amino acid ibotenic acid, which is toxic to humans. A few hours after eating the mushroom, it triggers confusion, speech disorders and hallucinations, among other things. In higher doses, it can cause seizures and, in extreme cases, death.
It is all the more surprising that Kenji Suetsugu from the University of Kobe in Japan and wildlife photographer Koichi Gomi have now observed a Japanese squirrel (Sciurus lis) feeding on these poisonous mushrooms. They managed to track this rodent for several days and photographed it eating fly agarics and panther mushrooms, among other things.
Whether the ibotenic acid has no effect on the Japanese squirrel at all, the researchers cannot say for sure. However, they conclude from their observations that squirrels have generally adapted to being able to eat the poisonous mushrooms without any problems. They also suspect that the fungus itself might even derive some benefit from it.
“But fungus eaters do not always have to be disadvantageous for the fungi, since they can also spread them via intact spores after digestion,” say Suetsugu and Gomi in their report. In order to test this hypothesis, the next step is to investigate whether viable fungal spores can be found in the rodents’ faeces. If this is the case, the squirrels, as dispersers of such spores, could have an important impact on the local ecosystem, since, among other things, some trees also live in a symbiotic relationship with the toadstools.