A discriminating bird in the zone:「Terns have a world-wide distribution, breeding on all continents including Antarctica. The northernmost and southernmost breeders are the Arctic Tern and Antarctic Tern respectively. Many terns breeding in temperate zones are long-distance migrants, and the Arctic Tern probably sees more annual daylight than any other animal as it migrates from its northern breeding grounds to Antarctic waters, a return journey of more than 30,000 km (18,600 mi). A Common Tern that hatched in Sweden and was found dead five months later on Stewart Island, New Zealand, must have flown at least 25,000 km (15,500 mi). Actual flight distances are, of course, much greater than the shortest possible route. Arctic Terns from Greenland were shown by radio geolocation to average 70,000 km (43,000 mi) on their annual migrations.」
　　[　https://en.wikipedia.org/wiki/Tern 2013-08-02　]　
　Terns are no longer considered to be seagulls.
　「Restricted zone birds」equates GULLS with service providers:「Gulls are typically medium to large birds, usually grey or white, often with black markings on the head or wings. They typically have harsh wailing or squawking calls, stout, longish bills, and webbed feet. Most gulls…are ground-nesting carnivores, which will take live food or scavenge opportunistically. Live food often includes crabs and small fish. Gulls have unhinging jaws which allow them to consume large prey. …The large species take up to four years to attain full adult plumage, but two years is typical for small gulls. Large white-headed gulls are typically long-lived birds, with a maximum age of 49 years recorded for the herring gull. Gulls nest in large, densely packed noisy colonies. …Gulls—the larger species in particular—are resourceful, inquisitive and intelligent birds, demonstrating complex methods of communication and a highly developed social structure. For example, many gull colonies display mobbing behaviour, attacking and harassing would-be predators and other intruders. Certain species (e.g., the herring gull) have exhibited tool use behaviour, using pieces of bread as bait with which to catch goldfish, for example. Many species of gull have learned to coexist successfully with humans and have thrived in human habitats. Others rely on kleptoparasitism to get their food. Gulls have been observed preying on live whales, landing on the whale as it surfaces to peck out pieces of flesh.」
　　[　https://en.wikipedia.org/wiki/Gull 2014-11-16　]　

Modern definitions (that generally disregard history) …excluding politically incorrect concepts and other meanings deemed offensive today; may list only pigeonholed definitions, euphemisms, or meaningless mnemonics)
Chinese: common gull
Unihan extended: seagull, tern; Larus species (various)
EDRDG: seagull; tern