Adjective
thin on the ground (comparative thinner on the ground, superlative thinnest on the ground)
scarce, or difficult to find.
Episcopalians are pretty thin on the ground in the central United States. Charlaine Harris
They seem much rarer now, those auteur films that come out of a director's imagination and are elliptical and hermetic. All those films that got me into independent cinema when I was watching it seem thin on the ground. Toby Jones