My first acquaintance with this species took place whilst I was at Cincinnati, in the beginning of August 1819. I was crossing the Ohio, along with Mr Robert Best, then curator of the Cincinnati Museum, for the purpose of visiting the Cliff Swallows which had taken up their abode on the walls of the garrison on the Kentucky side, when we observed two Gulls sweeping gracefully over the tranquil waters. Now they would alight side by side, as if intent on holding a close conversation; then they would rise on wing and range about, looking downwards with sidelong glances, searching for small fishes, or perhaps eyeing the bits of garbage that floated on the surface. We watched them for nearly half an hour, and having learned something of their manners, shot one, which happened to be a female. On her dropping, her mate almost immediately alighted beside her, and was shot. There, side by side, as in life, so in death, floated the lovely birds. One, having a dark bluish nearly black head, was found to be the male; the other, with a brown head, was a female. On the 12th of November 1820, I shot one a few miles below the mouth of the Arkansas, on the Mississippi, which corresponded in all respects with the male just mentioned.
No sooner do the shads and old-wives enter the bays and rivers of our Middle Districts, than this Gull begins to shew itself on the coast, following these fishes as if dependent upon them for their support, which however is not the case, for at the time when these inhabitants of the deep deposit their spawn in our waters, the Gull has advanced beyond the eastern limits of the United States. However, after the first of April, thousands of Bonapartian Gulls are seen gambling over the waters of Chesapeake Bay, and proceeding eastward, keeping pace with the shoals of fishes.
During my stay at Eastport in Maine, in May 1833, these Gulls were to be seen in vast numbers in the harbour of Passamaquody at high water, and in equal quantities at low water on all the sand and mud-bars in the neighbourhood. They were extremely gentle, scarcely heeded us, and flew around our boats so close that any number might have been procured. My son John shot seventeen of them at a single discharge of his double-barrelled gun, but all of them proved to be young birds of the preceding year. On examining these specimens, we found no development of the ovaries in several, which, from their smaller size, we supposed to be females, nor any enlargement of the testes in the males; and as these young birds kept apart from those which had brown and black hoods, I concluded that they would not breed until the following spring. Their stomachs were filled with coleopterous insects, which they caught on the wing, or picked up from the water, into which they fell in great numbers when overtaken by a cold fog, while attempting to cross the bay. On the 24th of August 1831, when at Eastport with my family, I shot ten of these Gulls. The adult birds had already lost their dark hood, and the young were in fine plumage. In the stomach of all were shrimps, very small fishes, and fat substances. The old birds were still in pairs.
When exploring the Bay of Fundy, in May 1833, I was assured by the captain and sailors, as well as the intelligent pilot of the Revenue Tender, the Nancy, that this Gull bred in great abundance on the islands off Grand Manan; but unfortunately I was unable to certify the fact, as I set out for Labrador previous to the time at which they breed in that part of the country. None of them were observed on any part of the Gulf of St Lawrence, or on the coast of Labrador or Newfoundland. In winter this species is common in the harbour of Charleston, but none are seen at that season near the mouths of the Mississippi.
The flight of this Gull is light, elevated, and rapid, resembling in buoyancy that of some of our Terns more than that of most of our Gulls, which move their wings more sedately. I found the adult birds in moult in August. Although their notes are different from those of all our other species, being shriller and more frequent, I am unable to represent them intelligibly by words.
Since I began to study the habits of Gulls, and observe their changes of plumage, whether at the approach of the love season, or in autumn, I have thought that the dark tint of their hoods was in the first instance caused by the extremities of the feathers then gradually changing from white to black or brown, without the actual renewal of the feathers themselves, as happens in some species of land-birds. At Eastport, I had frequent opportunities of seeing the black-hooded males copulating with the brown-hooded females, so that the colour of the head in the summer season is really distinctive of the sexes. I found in London a pair of these birds, of which the sexes were distinguished by the colour of the head, and which had been brought from Greenland. They were forwarded by me to the Earl of Derby, in whose aviaries they are probably still to be seen.
This is certainly the species described in the Fauna Boreali-Americana under the same name; but it is there stated that the females agree precisely with the males, their hood being therefore “greyish-black;” which I have never found to be the case. As to the Larus capistratus of Bonaparte’s Synopsis, I have nowhere met with a Brown-headed Gull having the tail “sub-emarginate;” and I infer that the bird described by him under that name is merely the female of the present species.
Larus Bonapartii, Bonapartian Gull, Richards. and Swains. Fauna Bor.-Amer. vol. ii. p. 425.
Brown-masked Gull, Larus capistratus, Bonap. Amer. Ornith., vol. iv. Female.
Larus capistratus, Ch. Bonaparte, Synopsis of Birds of United States, p. 358.