A Graveyard and a Nursery
In a limestone cave in the Dominican Republic’s arid southwest, a intersection of life and death is preserved. The site, Cueva de Mono, contains the first and only known instance of bees building nests inside the bones of other animals. The cave floor consists of red clay packed with the fossilized remains of extinct sloths, birds, reptiles, and rodents. Many of these bones were carried into the cave over thousands of years by a giant barn owl that used the cavern as a roost. The owl would regurgitate pellets of indigestible bones, creating a dense layer of skeletal remains on the cave floor.
Sometime around 20,000 years ago, solitary burrowing bees entered the cave and found this bone-littered floor. In an area where deep soil is scarce, the hollows within these discarded skeletons provided an ideal shelter. Researchers using micro-CT scans revealed that bees built their brood cells inside these natural cavities. They found nests located in the empty tooth sockets of extinct rodents, the vertebral canal of a hutia (a large Caribbean rodent), and even the pulp cavity of an extinct ground sloth's molar. Each tiny nest, smaller than a pencil eraser, was constructed from a mixture of dirt and saliva. Inside these hardened capsules, the mother bee would place a supply of pollen and nectar for her larva to eat after hatching.