And although the presence of the fairies on the wooded hilltops is a superstition, the Department of Agriculture says that could have been the only thing that protected the forts from destruction over the years.

While the wooded monuments have traditionally commanded respect down the centuries, the department says other forms of protection are needed to ensure their survival.

Officials are keen to work with farmers to make sure fairy forts survive for the benefit of future generations.

Patrick McGurn, of Countryside Management Branch, says many forts have been left untouched because of the traditional association with fairies.

However, the true origins of forts were as farmsteads, built to allow the family to bring their cattle in at night.

"There is some evidence that they are linked with dairy farming. Dairy cows offered the production of milk and meat, with butter an important bartering tool," Mr McGurn said.

In time, the forts were abandoned, although houses were often built beside them. Superstition protected the forts and slowly the growth of scrub on banks transformed them into the familiar wooded outline.

"One aim of agri-environment schemes is to enhance landscape and heritage features such as forts," Mr McGurn said.

"Individual management plans are drawn up with the farmer with any threat to the monument identified."