Did Fairy Belief Protect Ireland's Ringforts? Ringforts and Other Earthworks on the Ordnance Survey Maps and in the Sites and Monuments Record

Irish ringforts were long known as fairy forts that it was unlucky to disturb, and that belief is often said to explain why so many survive. I test the claim with the full Sites and Monuments Record for the Republic of Ireland (151,308 records, 31,431 ringforts), comparing ringforts with earthworks of similar build: enclosures, barrows, moated sites, mounds and other earthworks. Two proxies of survival are used: whether a site drawn on the first Ordnance Survey six-inch map (c.1840) is still drawn on the latest edition in the record, and whether the survey notes say it has no visible surface trace. On the maps, 88.6% of ringforts drawn c.1840 are still drawn, against 88.0% of barrows, 80.6% of moated sites and 70.1% of enclosures. In the notes, 16.3% of ringforts drawn c.1840 have no visible trace, against 42.4% of enclosures. But the record's classes depend partly on survival: 52% of unclassified ringforts have gone. Pooling ringforts and enclosures as round earthworks, 84.5% stayed on the map after adjustment for county, elevation and slope, against 86.3% for barrows and 86.6% for moated sites. Elevation is strongly associated with survival. Only 28 of 28,410 ringfort notes mention fairies or related beliefs, and townland names and names written on the 1840 map show little or no association with survival once county is allowed for. The national record shows no clear fairy premium. Interactive version: https://tristan-hotham.github.io/fairy-forts/. Data and code: https://github.com/Tristan-Hotham/fairy-forts. Blog post: https://blog.tristanhotham.com/2026/10/27/fairy-forts/.