Bonapartian Gull

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 shad 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 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 gambolling 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 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. 

BROWN-MASKED GULL, Larus capistratus, Bonap. Amer. Orn., vol. iv. Female. 
LARUS CAPISTRATUS, Bonap. Syn., p. 358. 
LARUS BONAPARTII, Bonapartian Gull, Swains. and Rich. F. Bor. Amer.,vol. ii. p. 425. 
BONAPARTIAN GULL, Nutt. Man., vol. ii. p. 294. 
BONAPARTIAN GULL, Larus Bonapartii, Aud. Orn. Biog., vol. iv. p. 212. 

Adult, 14 1/8, 32 1/4. 

Extremely abundant in winter, on the coast of Florida. Equally plentiful in spring, along the coasts of the Middle and Eastern Districts, especially in the Chesapeake. Breeds from the Bay of Fundy to high latitudes. Not uncommon in autumn, on the Great Lakes, and the Ohio and Mississippi. 


Adult Male in spring plumage. 

Bill shorter than the head, nearly straight, slender, compressed. Upper mandible with its dorsal line straight to the middle, then curved and declinate, the ridge narrow, the sides slightly convex, the edges sharp and a little inflected, the tips narrow but rather obtuse, with a slight notch on each side. Nasal groove rather long and narrow; nostrils in its fore part, longitudinal, sub-medial, linear, pervious. Lower mandible with a slight prominence at the end of the angle, which is long and narrow, the dorsal line then ascending and slightly concave, the ridge convex, the sides nearly erect and flattened. 

Head of moderate size, ovate, narrowed anteriorly, convex above. Eyes of moderate size. Neck rather short. Body rather slender. Wings very long. Feet of moderate length, rather strong; tibia bare below for a short space, covered behind with narrow scutella; tarsus compressed, anteriorly covered with numerous scutella and three inferior series of transverse scales, laterally with oblong scales, posteriorly with oblique scutella. Toes slender, with numerous scutella; first extremely small, second considerably shorter than fourth, third longest; anterior toes connnected by reticulated webs, of which the anterior margins are deeply concave, the outer and inner slightly marginate. Claws small, compressed, moderately arched, rather obtuse, that of middle toe with an expanded inner edge. 

Plumage full, close, soft, blended. Wings very long and pointed; primaries tapering and rounded, first longest, second very little shorter, the rest rapidly graduated; secondaries obliquely pointed, the rounded extremity extending beyond the tip of the shaft, which is exterior to it, the inner feathers more elongated. Tail of moderate length, almost even, the middle feathers slightly longer. 

Bill black, inside of mouth vermilion. Iris reddish-hazel. Feet orange, slightly tinged with vermilion; claws dusky brown. Head and upper part of neck all round, greyish-black, that colour extending half an inch lower on the throat than on the occiput. A white band divided by a narrow black line margining the eye behind; the remaining part of the neck white; back, scapulars and wings, light greyish-blue. The anterior ridge of the wing, alula, smaller coverts on the carpal margin, four outer primary coverts, shaft and inner web of the outer primary, both webs of second, inner webs of third and fourth, white; of which colour also are the rump, tail, and all the lower parts. Outer web of first quill, excepting a small portion towards the end, its tip to the length of half an inch, black, as are the ends of the next six, which however have a small tip of white, the black on some of them about an inch long, and running along the inner edge to a considerable extent. 

Length to end of tail 14 1/8 inches, to end of wings 15 5/8, to end of claws 13 1/8; extent of wings 32 1/4; wing from flexure 10 3/4; tail 4 2/12; bill along the ridge 1 4/12, along the edge of lower mandible 1 10/12; tarsus 1 3/12; hind toe and claw (3 1/4)/12; middle toe 1 3/12, its claw (3 1/4)/12; outer toe 1 (1/2)/12, its claw (2 1/4)/12; inner toe 11/12, its claw (2 1/2)/12. Weight 6 1/2 oz. 


Adult Female. 

The female is somewhat smaller, and resembles the male, but has the head and upper part of the neck umber-brown. 


Young in December. 

Bill greyish-black, iris dark brown; feet flesh-coloured, claws dusky. Head and neck greyish-white; a small black patch about an inch behind the eye on each side. Upper parts dull bluish-grey, many of the wing-coverts greyish-brown, edged with paler; quills as in the adult; rump and tail white, the latter with a broad band of black at the end, the tips narrowly edged with whitish. 

Length to end of tail 13 3/8, to end of wings 15 5/8, to end of claws 13; extent of wings 32 1/2 inches. Weight 6 oz. 

The white spots on the tips of the wings vary greatly in size, and are frequently obliterated when the feathers become worn. 

Palate with five series of small distant papillae. Tongue 1 inch 1 twelfths long, slender, tapering to a slit point, emarginate and papillate at the base, horny towards the end. Aperture of posterior nares linear, 9 twelfths long. Heart 1 inch long, 9 twelfths broad. Right lobe of liver 1 inch 11 twelfths long, the other lobe 1 inch 7 twelfths. 

The oesophagus is 6 1/2 inches long, very wide, with rather thin parietes, its average diameter when dilated 10 twelfths, within the thorax enlarged to 1 inch 2 twelfths. The transverse muscular fibres are distinct, the internal longitudinal less so; the mucous coat longitudinally plicate. The proventriculus is inch long, with very numerous small glandules. The stomach is a small oblong gizzard, 10 twelfths long, 8 twelfths broad; its lateral muscles rather large, as are its tendons. The inner coat or epithelium is of moderate thickness, dense, with nine longitudinal broad rugae, and of a brownish-red colour. The intestine is 24 1/2 inches long, its diameter 2 twelfths. The rectum is 1 1/2 inches long. The coeca are 2 twelfths long, 1 twelfth in diameter, cylindrical and obtuse. 

The intestine of another individual, a male, is 20 1/2 inches long, 3 twelfths in diameter. 

The trachea is 3 inches 10 twelfths long, its diameter at the top 3 twelfths, at the lower part 2 1/4 twelfths, the rings very feeble, unossified, about 130 in number. The sterno-tracheal muscles are very slender, as are the contractors; and there is a pair of inferior laryngeals. The bronchi are of moderate length, with about 18 half rings.
 

For more on this species, see its entry in the Birds of North America Field Guide.