Photos show how ants escaped a Soviet nuclear-weapons bunker after surviving on cannibalism for years

Wood ants on the earth mound in the bunker on September 18, 2016.

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Wood ants on the earth mound in the bunker on September 18, 2016.
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Wojciech Stephan

Scientists finally understand how a colony of ants survived for years in a cold, dark bunker: cannibalism.

The wood ants had fallen through a ventilation pipe into a Soviet-built bunker, once used to store nuclear weapons, in the forests of Poland. Once inside, the ants were trapped with only other worker ants and millions of corpses.

The plight of those ants is detailed in a study published in October in the Journal of Hymenoptera Research.

Here’s their harrowing tale.


A colony of ants recently escaped a Soviet-era bunker in Poland once used to store nuclear weapons.

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The partly blocked entrance to the bunker system.
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Wojciech Stephan

Researchers studying wood ants in the forests of Poland first stumbled upon the unfortunate colony in 2013. They estimated that almost 1 million ants were inside the bunker but couldn’t tell how long they’d been trapped there.

The bunker had been part of a Soviet nuclear base from the late 1960s to 1992.


The scientists found only worker ants in the bunker, with no queen and no larvae.

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Worker ants in the bunker.
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Wojciech Stephan

The ants didn’t seem to produce any offspring, likely because of low temperatures and lack of food.


The bunker colony grew as ants from the original colony in the forest fell through a ventilation pipe beneath their nest.

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The mound of the free-living wood ant colony built on the outlet of the ventilation pipe,
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Wojciech Stephan

In total darkness, the bunker colony built its own mound from dirt on the bunker floor.


Freedom was always just out of reach. Since they couldn’t move along the ceiling, the ants couldn’t climb back up the pipe.

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The ants (climbing up the wall on the left) were unable to move along the ceiling, so they could not reach the ventilation pipe.
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Wojciech Stephan

The researchers could get in and out of the bunker through cracks that the ants couldn’t access. They started to think about how they could help the ants escape.


The ants’ food source remained a mystery until the researchers came back in 2016 and examined some of the 2 million ant corpses piled up around the bunker.

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The wood ants built an earthen mound in the bunker.
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Wojciech Stephan

“I wasn’t surprised,” Maák István, an ant ecologist who helped write the study, told Popular Science. “It was a logical option for them to survive in this way.”

Of the corpses that the researchers collected, 93% had bites or holes indicating that other ants had eaten them. The living ants had punctured the abdomens of dead ants to suck out their innards, “like opening a can,” István said.

The researchers examined only dead ants that still had their abdomens, to avoid double-counting pieces of the same corpses.


Then the scientists noticed an old wooden plank leaning against the bunker wall. The trail of ants climbing to the ceiling began there.

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A piece of board leaning against the wall was the beginning of an ant trail up the wall.
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Wojciech Stephan

Maybe the researchers could provide direct access to the ventilation pipe.


So they set up a 9-foot “boardwalk” from the ants’ mound to the ventilation pipe above.

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The boardwalk gave the ants a way to reach the ventilation pipe.
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Wojciech Stephan

“It was meant to serve as an escape route, allowing the ants to leave the bunker,” the researchers wrote.

Before the researchers left, they noted that some ants started inspecting the boardwalk right away.


When the researchers returned to the bunker a few months later, all but a few stray ants were gone, leaving behind piles of partially cannibalized corpses.

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The earth mound at the bottom of the bunker in winter 2017, four months after the boardwalk was set. “Ant cemeteries” are visible around the mound and next to the walls.
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Wojciech Stephan

In the end, the scientists marveled at the ants’ perseverance and adaptability.

“The ecological and behavioural flexibility of the wood ants may allow them survival even in unexpectedly suboptimal conditions,” they wrote.