They can be up to 80-feet wide and cover portions of the landscape for miles. A new theory by researchers at the University of Strathclyde and Princeton may have finally discovered their cause.

Until now there have been two competing arguments for the circles’ presence. One suggests that the desert shrubs are solely responsible – that they cause the circles by competing among themselves for rainwater.

The second argues it is in fact termites living underground destroying vegetation above their colonies, who, in an effort to reduce competition for water, then create barren discs of sand at the circumference of their reach.

The real reason could be somewhere in the middle. ‘Both theories are normally presented as mutually exclusive,’ says Dr Juan Bonachela, an ecologist from the University of Strathclyde and co-author of the study. ‘Our findings harmonise both.’

To create the ‘Fairy Circles’ (once believed to have been caused by the gods or spirits by the indigenous Himba people, and therefore ascribed spiritual and magical powers) termites ‘remove vegetation on their mounds to increase moisture, which is essential for the insects’ survival in dry environments, thus creating a bare disc,’ Bonachela says.

“Vegetation around the mound takes advantage of this water accumulation to grow, and this taller vegetation forms the circle. The desert is a very competitive place for water, and where there are large areas with many circles it is from different termite colonies competing next to one another”

For Bonachela, the Fairy Circles ‘remind us of the delicate balance of interactions necessary to sustain ecosystems.’ The mutual interactions are necessary because they allow the ecosystem to better survive periods of drought. By combining field samples from similar patterns in Kenya, Mozambique, Brazil, North America and Australia, the research could also offer explanations for arid vegetation patterns all over the world.

This was published in the April 2017 edition of Geographical magazine.