The Brown Noddy is distributed in the tropics and sub-tropics mainly south of the Equator. It breeds on islands and coral reefs and nests on cliffs, in trees or, as is the case at Michaelmas Key, on the ground.

It is dark chocolate brown with a pale grey crown turning to white on the forehead. The sub-species found in Australia A. s. pileatus, is noted as having a more bluish-grey crown.