Bees are extraordinary and extraordinarily adaptable animals. Those that nest in the ground, known in English as “burrowing bees“, they are particularly good at exploiting any substrate available to dig their nests. Until now, however, we had not yet seen bees that build nests in the fossil bones of other animals.
An extraordinary new study published on Proceedings of the Royal Society B Biological Sciences describes a fossil, discovered on the Caribbean island of Hispaniola, which testifies to the first known case of bees using the remains of other animals to build their own nest.
It all started with owls. To understand how bees ended up nesting inside other people’s bones, we need to start with owls. The cave where the fossils were found was, 20 thousand years ago, frequented by a population of a species of large barn owl.
The meals of these birds included large local rodents, the hutiawhich can reach half a meter in length and 9 kg in weight. The cave, therefore, 20 thousand years ago was therefore covered with the remains of these and other animals, which were buried by the silt transported by precipitation.
Nests in the jaws. Here, the corpses of hutia they began to fossilize. The bees, in an area where the soil is poor and very thin, have found, in the clay of the cave, the ideal substrate for digging their nests, going against their habit of building them in the open air and not in closed spaces.
Digging in the silt, the bees discovered the bones of the hutiain particular some jaws – now toothless. The bees thus built their nest in the alveoli that housed them, and there they were discovered, 20,000 years later, by the team from the Florida Museum of Natural History.
Bees, not wasps! Curiously, the first attempt to describe this fossil was unsuccessful: the first author of the study, Lazaro Viñola Lopez, was convinced that the remains belonged to fossil wasps, which in the past had already been “caught” pupating in the bone cavities of various animals. The first version of the study was therefore about them, not about bees: it took more in-depth analysis to identify what is the first known case of bees making a nest in the fossil bones of another species.
A variety of colonized animals. Further studies of the cave have also revealed other fossils “colonised” by bees: for example, the jaw of a tree sloth, once widespread in the Caribbean (and driven to extinction by the arrival of humans).
As for why, we already mentioned it above: Hispaniola’s soil is very thin and nutrient-poor, and bees don’t have much to work with to build their nests. The barn owl cave therefore proved to be an ideal environment, and the convenience of the hutia bones an added bonus.
