Terns range in size from the least tern, at in length and weighing ,Maehr & Kale (2005) p. 111.Olsen & Larsson (1995) p. 136. to the Caspian tern at , .Harrison (1988) p. 368.Olsen & Larsson (1995) p. 25. They are longer-billed, lighter-bodied, and more streamlined than gulls, and their long tails and long narrow wings give them an elegance in flight. Male and female plumages are identical, although the male can be 2–5% larger than the female and often has a relatively larger bill. Sea terns have deeply forked tails, and at least a shallow "V" is shown by all other species. The noddies (genera Anous, Procelsterna and Gygis) have unusual notched-wedge shaped tails, the longest tail feathers being the middle-outer, rather than the central or outermost.Harrison (1988) pp. 387–390.Hutton & Drummond (2011) p. 226. Although their legs are short, terns can run well. They rarely swim, despite having webbed feet, usually landing on water only to bathe.
