All winter, a traveler along the seashore sees the great gray gulls wheeling gracefully through the air with outstretched wings, floating lightly on the water, or sitting in long lines or compact masses on the bars or flats which are exposed at low tide. The harbors of all the northern seacoast cities are visited in winter by numbers of these birds, constantly on the watch for any bits of refuse which may be thrown from the wharfs or vessels, or brought down by the tides or currents. Their long and powerful wings make the flight of even so heavy a bird a sight beautiful to watch, and the water looks deserted when the motion and color which the gulls furnish is absent. But it is not to the eye alone that the birds appeal.

The ceaseless activity of the gulls in pursuit of floating refuse and their inordinate appetite make them invaluable scavengers; without them, the refuse dumped into the water would return at each tide to pollute the shore. No idea can be formed of the value of the service performed by the gulls, till one sees the countless throngs which hover over the dumping grounds in the lower New York Bay, awaiting the arrival of the scows with the refuse from that city. As the buzzards and vultures are protected in all warm countries for their services in devouring carrion, so ought these scavengers of the northern seas to be guarded from persecution.

The adult Herring Gull in full plumage has pure white underparts, head and tail, but a gray mantle, as it is termed, is spread over the wings. Young birds, however, show many shades of brown, and attain the white only after a year or two. The small, elegantly built birds, known along the seacoast as Mackerel Gulls, are not strictly gulls, but terns. They may be known by their forked tails and by their black caps. It is they that hover screaming over the water, constantly darting down to strike at fish.

Gulls breed commonly along the coast of Maine and far northward. Great colonies occupy a small area, and a visit to their breeding places is a marvelous experience. At the approach of an intruder, the parents rise from their nests and circle about overhead, uttering hoarse cries, till the air is full of their wheeling forms. The downy young squat in the grass or bushes till the danger is past.

Both gulls and terns have long been persecuted for their soft white and gray plumage, which is coveted for the adornment of women's hats. As the destruction of the birds on the islands where they are breeding would soon destroy the whole race, efforts are being made by the lovers of birds to protect the birds on all the sandy points or rocky islands where they rear their young.

Gulls have wonderful powers of flight, and some species often follow ocean steamers for days, flying constantly about the vessel's stern, watching for bits of food which may be thrown overboard. When an object is spied the whole flock dart upon it, and it soon disappears among the crowd of struggling birds.

In the Eastern States gulls are always associated with the sea, but in the Mississippi valley certain species are found on the prairies, where they follow the plough to seize the upturned insects.