This sub-species has been treated by some authorities as a separate species. It is now generally regarded as a sub-species of Sandwich Tern and the HBW and Birdlife International Checklist has treated the sub-species eurygnathus as a synonym of acuflavidus since the two interbreed freely in the Caribbean. However, Clements treat the two sub-species separately giving the name Cabot's Tern to T. s. acuflavidus.