The blue noddy (Procelsterna cerulea) is a species of tern in the family Sternidae. It is also known as the blue-grey noddy.
It is found in American Samoa, the Cook Islands, Fiji, French Polynesia, Kiribati, Marshall Islands, New Caledonia, Samoa, Tonga (Niua), Tuvalu and Hawaii. It has occurred as a vagrant in Australia and Japan. Its natural habitat is open, shallow seas in tropical and subtropical regions.
There are five listed subspecies:
P. c. saxatilis (Fisher, 1903): Marcus Island & north Marshall Islands to northwest Hawaii
P. c. cerulea (Bennett, 1840): Kiritimati Island & the Marquesas Islands
P. c. nebouxi (Mathews, 1912): Phoenix Islands, Tuvalu, Fiji & the Samoan Islands
P. c. teretirostris (Lafresnaye, 1841):Tuamotu Archipelago, Cook, Austral & Society Islands
P. c. murphyi (Mougin & Naurois, 1981): Gambier Islands (French Polynesia)
The grey noddy (Procelsterna albivitta) replaces it to the south of its range; the two were formerly considered to be a single species but are now often split.