The Cannibal Ants of the Soviet Bunker

If there's one thing we've learned from insects (courtesy of a relationship with the human species that has spanned hundreds of thousands of years), it's that they can establish themselves almost anywhere. But one of the most interesting cases of adaptation takes us to Międzyrzecz, in western Poland. Hidden among pines and firs is an old Soviet bunker, transformed into a refuge for two colonies of wood ants. The first colony is relatively normal, with access to abundant food and sunlight, but deep inside, the second colony adapted to devour the bodies of its dead...

A Soviet Bunker in the Forest

It sounds like a story from an old horror movie, and I must admit there are several with ants as main antagonists, but this is 100 percent real. In a western Polish forest lies the "Special Object 3003", an abandoned Soviet bunker, abandoned immediately after the fall of the bloc. The role of such bunkers was to conceal the construction of weapons and their subsequent storage (both conventional and nuclear). During the retreat, those responsible for Object 3003 sealed all entrances, but the work was half done, and nature quickly moved in.

Discovery and Two Colonies

The ants were discovered in 2013, when a team was monitoring the health of bats that often inhabit abandoned bunkers like 3003. The bunker is connected to the surface through a ventilation tube about five meters long, while the other end leads to a strange room identified as number 12. Too small to serve as a cell... but we'll never know.

Near the top and very close to the tube is Colony One, which enjoys all the forest's advantages: ample space, sunlight, and honeydew as food. However, those ants unlucky enough to fall down the ventilation tube got a one-way ticket to Colony Two. There is no light, no food, and no escape due to the distance between the tube and the ground. How did the colony survive under such extreme conditions? Well... zoologist István Maák of the Polish Academy of Sciences in Warsaw explains it bluntly: by eating the dead.

Experts acknowledge that this is not unusual behavior in wood ants. Conflicts between colonies that develop during spring while searching for food are very important, and survivors often devour the defeated. Facing a lack of alternative food sources (even bat guano is not enough), Colony Two's response was pure instinct. More than a colony, the researchers found the equivalent of a necropolis, with nearly two million bodies organized in 'dumps' located at the edges of the room.

Of course, the ants tried to find a way out of the bunker, with some expeditions taking considerable distance from the colony. Another notable detail is that Colony Two had no reproduction: no queen and no larvae. Its population was sustained by members of Colony One falling through the tube, maintaining an average of one million individuals. In 2015, researchers excavated Colony Two's mound, right below the ventilation tube, expecting to find pupae, but without success. A year later, they confirmed that the ants had repaired the mound.

Ethical Dilemma and Public Outcry

The study was published by Wojciech Czechowski and his team in the Journal of Hymenoptera Research in mid-2016, emphasizing the perseverance and determination of Colony Two, but the public's response was quite different. Professor Maák began receiving letters from people claiming that leaving the ants there was an act of cruelty and that they should be rescued. Now, one of the fundamental rules in research of this kind is non-intervention, causing the least possible harm. Maák explored the ethical conflict with his colleagues, and they concluded that intervention had already happened: the ants were trapped in a human-built structure.

At the same time, the experts had already learned all they could from Colony Two, so they began the reunification process. The first step was to determine, beyond any doubt, that the ants from both colonies would not be hostile to each other. Wood ants have a very specific chemical profile (experts compare it to a 'barcode'), which is 'read' to distinguish friends from enemies. In the spring of 2016, Professor Maák took a group of a hundred ants from Colony Two and placed them near the entrance of Colony One. The 'new' ants were not attacked and reintegrated almost immediately into the colony.

So what was the solution? Building a bridge. Maák's colleagues installed a wooden plank connecting the floor of room 12 to the ventilation tube through which the ants had originally fallen. Before they left, some Colony Two ants had begun exploring the plank. Maák could only return to the bunker in February 2017: Colony Two no longer existed. All its members had returned to the surface. The only thing left was the necropolis, and a few ants near the plank, which probably fell back down the tube.

Source: Atlas Obscura. First study: Click here. Second study: Click here.