Ancient burrowing bees carved out nests inside the tooth cavities and vertebrae of deceased rodents, a groundbreaking fossil discovery reveals.
More than 5,000 years ago, these bees settled into burrows within piles of rodent bones buried in a cave on Hispaniola, the Caribbean island shared by the Dominican Republic and Haiti. While excavating to their preferred depth in the soil, the bees paused to build nests inside the bone cavities, which happened to be just the right size for their purposes, according to researchers.
Most of the bones unearthed by the team belonged to hutias—stout, beaver-sized rodents that resemble a blend of squirrels and beavers—though a few belonged to an extinct sloth species.
The researchers described the fossilized nests as Osnidum almontei, noting that the nest cells appear highly opportunistic, filling all available bony chambers within the sediment deposit.
The bees likely encountered the hutia bones long after the rodents were deposited in the cave by Hispaniolan barn owls (Tyto ostologa), which are now extinct. The study suggests that these owls sometimes carried hutias into the cave intact and discarded the bones after feasting, or regurgitated pellets containing hutia remains from prey. Barn owl bones found in the cave corroborate the owls’ historical presence in the area.
Over time, collapsing sediments buried these bone piles. Later generations of burrowing bees took advantage of the preserved cavities, even though these bees typically nest in open soil.
In one tooth cavity, six nested bee nests were discovered, indicating multiple generations using the same site after earlier nests had been abandoned.
The team wonders why the bees opted for a cave over open terrain. Mitchell Riegler, a teaching assistant at the University of Florida and co-author of the study, explains that the local landscape is karst with sharp limestone that has eroded away most natural soils, leaving little to no earth suitable for burrowing.
After fieldwork, researchers faced plans to repurpose the cave as a septic storage facility. A rescue effort salvaged as many fossils as possible, though the project to install a septic tank ultimately did not proceed.
The collected fossils are still awaiting full analysis, and the researchers anticipate publishing additional findings in future studies.
Sascha is a UK-based Live Science staff writer with a biology degree from the University of Southampton and a master’s in science communication from Imperial College London. Her work has appeared in The Guardian and Zoe. Outside of writing, she enjoys tennis, bread making, and hunting for hidden gems in second-hand shops.
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