This striking triangular postage due stamp from Mauritania features the Grue cendrée (Grey Crane), beautifully engraved with fine cross-hatching and soft yellow–orange shading. Issued by the République Islamique de Mauritanie, the stamp carries a 0.50f denomination and the inscription Timbre Taxe, marking its use for underpaid mail fees. The design presents the crane standing in a marshland setting, a classic example of French-influenced African colonial engraving by R. Serres and printed by Chaix. A desirable thematic piece for collectors of birds, triangular issues, and African fiscal/postage due stamps.