AI-generated editorial illustration by PW; not a reconstruction of the ancient site.
More than 8,000 frog bones in one ditch is a lot of unfinished business. Archaeologists found them during roadworks near Cambridge, and for years the tiny remains left a big question: what had happened to all those frogs?
The likely culprits had wings. Researchers at Bournemouth University and Museum of London Archaeology now point to birds of prey, especially short-eared owls and hen harriers. Their conclusion turns an ancient mass-death mystery into something stranger in its own way: the leftovers of a remarkably productive hunting season.
The damage gave them away
The bones emerged during excavations for the A14 Cambridge-to-Huntingdon improvement scheme between 2016 and 2018. MOLA drew attention to the puzzle in 2022. The new findings concern those existing remains, not a frog graveyard uncovered this week.
According to Bournemouth’s November 10 announcement, Dr Paul Clarkson compared damage on the bones with earlier studies and identified signs of predation. The university’s report also shows a photograph of the actual bone samples, credited to MOLA/Andy Chopping.
That answered how the frogs died. It didn’t immediately explain the concentration. Archaeological evidence indicated the ditch had filled within a single year. Thousands of bones had accumulated in a surprisingly short window.
A very good winter for predators
Measurements of the frogs’ upper-arm bones supplied another clue. The researchers inferred that most had been eaten during their first winter. Radiocarbon dating placed the remains around 1,700 years ago, in the Roman period.
In MOLA’s account, retreating Fen waters created favorable breeding conditions. Meanwhile, woodland had gradually been cleared for grazing. Snail, pollen and charcoal evidence helped reconstruct that changing landscape. More open ground suited grassland-hunting birds.
Together, the findings suggest abundant young frogs and predators well placed to catch them. The researchers also suggest seasonal human use of the area may have left quieter hunting grounds. That last point is an interpretation of the landscape, rather than a directly observed event.
The bones outlasted the meal
The study identifies likely predators, not a particular bird caught in the act. Its payoff is the connection between small remains and a much larger scene: changing water, cleared woodland, grazing animals and hungry birds. A ditch full of frog bones has become a record of how that landscape worked.
Read next: The Ann Francis lock’s four-letter mystery follows another investigation in which close examination of a small surviving object revealed part of a much older story.
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