Gull, Tern and Skimmer are distantly related to each other except for some difference.
Gulls are typically medium to large birds, usually grey or white, often with black markings on the head or wings. Gulls have unhinging jaws which allow them to consume large prey. Gulls are typically coastal or inland species, rarely venturing far out to sea.
Terns are slender, lightly built birds with long, forked tails, narrow wings, long bills, and relatively short legs. 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
Skimmers are the only birds with distinctive uneven bills, where the lower bill is longer than the upper. This remarkable adaptation allows them to fish in a unique way, flying low and fast over streams. Their lower bill skims or slices over the water’s surface, ready to catch any small fish. Their bills fall within their field of binocular vision, which enables them to carefully position their bill and capture prey. They are agile in flight and gather in large flocks along rivers and coastal sand banks. In India, one can be found most in the bank of Chambal river, near Dholpur around 70 kms from Agra.
