Family XLII. LARINAE. GULLS. GENUS II. STERNA, Linn. TERN. |
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Family |
LEAST TERN. [Least Tern.] |
Genus | STERNA MINUTA, Linn. [Sterna antillarum.] |
As no account of this species exists in the Fauna Boreali-Americana, it is
to be supposed that it is not met with beyond the western shores of Labrador,
where however I found it in abundance, and breeding, in the beginning of June
1833. On the 14th of August following I observed them at Newfoundland, moving
southward in detached parties of old and young, against a strong breeze, and
uttering their clamorous cries. Again, in the end of April 1837, hundreds of
pairs were breeding on the islands of Galveston Bay in Texas, the numerous
specimens which I then examined exhibiting no difference from those obtained in
Labrador and in our Middle Districts. Nay, once, in the middle of June, while
wading through the quick-sands of Bayou Sara in Louisiana, I came to a high and
dry sand-bar where I picked up several eggs belonging to three pairs of birds of
this species, although the distance was about two hundred miles from the sea in
a direct line. I have at various times observed this Tern on the waters of the
Ohio in autumn, and now and then in spring, at the latter period in company with
the Short-tailed Tern, Sterna nigra, and have again met with it on the shores of
Lake Erie. I have also found it in winter on the eastern coast of the Floridas,
but in small numbers. Few birds indeed seem to me to be so irregular in their
migratory movements, for they appear to stop at any convenient breeding place
from Texas to Labrador.
Few birds are more gentle than this delicate species is at times; for,
apparently unaware of danger from the vicinity of man, it allows him to approach
within a few yards, whether it be on wing or on the ground. Indeed, in the
latter case, I have seen it when gorged so reluctant to fly off that I have more
than once thought it was asleep, although on coming up I was always disappointed
in my attempts to catch it. Nothing can exceed the lightness of the flight of
this bird, which seems to me to be among water-fowls, the analogue of the
Humming-bird. They move with great swiftness at times, at others balance
themselves like Hawks over their prey, then dart with the velocity of thought to
procure the tiny fry beneath the surface of the waters. When you invade their
breeding place, they will sometimes sweep far away, and suddenly return, coming
so near as almost to strike you. While travelling, their light but firm flight
is wonderfully sustained; and on hearing and seeing them on such occasions, one
is tempted to believe them to be the happiest of the happy. They seem as if
marshalled and proceeding to a merry-making, so gaily do they dance along, as if
to the music of their own lively cries. Now you see the whole group suddenly
check their onward speed, hover over a deep eddy supplied with numberless
shrimps, and dash headlong on their prey. Up rises the little thing with the
shrimp in its bill, and again down it plunges; and its movements are so light
and graceful that you look on with pleasure, and are in no haste to depart.
Should this scene be enacted while they have young in their company, the latter
await in the air the rise of their parent, meet them, and receive the food from
them. When all are satiated, they proceed on their journey, stopping at another
similar but distant place.
Although along our Southern and Middle Districts, the Least Tern merely
scoops a very slight hollow in which to deposit its eggs, doing this from the
first of April to the first of June, according to the latitude of the place,
those which I found breeding on the coast of Labrador had formed very snug
nests, composed of short fragments of dry moss, well matted together, and nearly
of the size of that of the American Robin, Turdus migratorius; while those met
with on the islands near the Bay of Galveston, were observed to have laid their
eggs upon the dry drifted weeds which appeared to have been gathered by them for
the purpose. The nests are generally placed out of reach of the tides, but on
some occasions I have known the hopes of a whole colony destroyed by the sudden
overflow of their selected places caused by a severe gale, and have observed
that, on such occasions, their clamour was as great as if they had been robbed
of their eggs by man.
The number of eggs deposited by this species is more frequently three than
four. Like those of most other Terns, they differ somewhat in size and
markings, although I never found any so large as those described by WILSON, who
states that they measure nearly an inch and three quarters in length, which
would better agree with the eggs of the Common Tern. The average of a basketful
was found to be one inch and two and a half eighths in length, by seven and a
half eighths in breadth. They are rather pointed at the smaller end, and their
ground colour is pale yellowish-white, blotched with irregular dark brown spots,
intermixed with others of a dull purplish tint.
I have found this Tern breeding among Shearwaters along the Florida coast;
and my friend the Reverend JOHN BACHMAN has observed the same circumstance on
the "Bird's Banks," on the coasts of South Carolina, where it is abundant, as
well as on Sullivan Island.
The common note of our Least Tern resembles that of the Barn Swallow when
disturbed about its nest, being as smartly and rapidly repeated at times. When
it proves convenient for it to alight on the ground or on a sand-beach, after it
has secured a prawn or small fish, it does so, and there devours its prey
piecemeal, but it more usually swallows it on wing. On the ground it walks
prettily, with short steps, keeping its tail somewhat raised.
LEAST TERN, Sterna minuta, Wils. Amer. Orn., vol. vii. p. 80.
STERNA MINUTA, Bonap. Syn., p. 355.
SILVERY TERN, Sterna argentea, Nutt. Man., vol. ii. p. 280.
LEAST TERN, Sterna minuta, Aud. Orn. Biog., vol. iv. p. 175.
Adult, 8 3/4, 18 3/4.
Breeds from Galveston along the shores to Labrador. Not mentioned as found
in the Fur Countries. Returns southward, and passes beyond Texas in autumn.
Extremely abundant at times on the Great Lakes, as well as the Ohio and
Mississippi.
Adult Male.
Bill about the length of the head, slender, tapering, much compressed,
nearly straight, extremely attenuated towards the end. Upper mandible with the
dorsal line slightly arched, the ridge rather broad and convex at the base,
narrow towards the end, the sides nearly erect, the edges sharp and direct.
Nasal groove short, extending to a fourth of the length of the bill; nostrils
basal, linear, direct, pervious. Lower mandible with the angle extremely
narrow, very acute, extending to the middle, the dorsal line straightish, the
sides erect, the edges sharp and inflected, the tip extremely acute.
Head of moderate size, ovate; neck short; body very slender; feet small.
Tibia bare below; tarsus very short, slender, compressed, covered anteriorly
with small scutella, laterally and behind with reticular scales; toes small,
slender, the first extremely small, the third longest, the fourth considerably
shorter, all scutellate above, the anterior united by reticulated webs having a
deeply concave margin. Claws arched, compressed, acute, that of hind toe
smallest, of middle toe by much the largest, and having its inner edge thin and
dilated.
Plumage soft, close, blended, very short on the fore part of the head; the
feathers in general broad and rounded. Wings very long, narrow, and pointed;
primary quills tapering, straight, the first longest, the next five-twelfths of
an inch shorter, the rest rapidly graduated; secondary quills short, broad,
incurved, narrowed towards the end, the inner straight. Tail rather long, very
deeply forked, the lateral feathers extending an inch and seven-twelfths beyond
the fork.
Bill light yellowish-orange, its tips black, but the extreme points
horn-colour. Iris hazel; feet light orange-red, the bare part of the tibia
dusky; claws black. On the forehead, a triangular white patch extending to the
middle of the eye; upper part of the head and the nape, with a line from the eye
to the bill, deep black; sides of the head, fore-neck and lower parts, pure
white; back and wings very pale bluish-grey; first two quills with the outer web
greyish-black, and rather less than half of their inner web of the same colour,
the rest white, extending to about half an inch from their extremities. Tail
white in summer, of a paler tint than the back at other times.
Length to end of tail 8 3/4 inches, to end of wings 9 1/2, to end of claws
7 1/2, to end of shortest tail-feathers 7; extent of wings 18 3/4; wing from
flexure 6 11/12; tail 3 1/2; bill along the ridge 7 1/2 twelfths, along the edge
of lower mandible 1 5/12; tarsus 7/12; middle toe 7/12, its claw 3/12.
The Female is a little smaller than the male, but otherwise similar.
Young fledged.
Bill greenish-black. Iris dusky. Feet pale yellowish-orange. All the
under parts dull greyish-white, as are the upper parts, including the tail; the
hind part of the head streaked with dusky, on the back and rump the feathers
with a curved marginal band of greyish-brown; primary quills greyish-brown, the
outer two darker. At this period the tail is even, each feather narrowly
margined with greyish-white.
In a male bird the tongue is 10 twelfths long, slender, triangular,
tapering to a point, horny beneath, emarginate and papillate at the base. On
the palate are five longitudinal ridges. The posterior aperture of the nares is
linear, 7 twelfths long. The oesophagus is 4 inches 2 twelfths long, very wide,
its average diameter on the neck 4 1/2 twelfths, within the thorax 9 twelfths;
it is exceedingly thin and delicate, its muscular fibres scarcely apparent,
unless closely examined. The proventriculus is only a quarter of an inch long.
The stomach is 9 twelfths long, 8 twelfths broad, its lateral muscles of
considerable size, the cuticular lining dense, tough, longitudinally rugous, and
of a reddish-brown colour, as in Gulls. Contents of stomach and oesophagus,
small fishes, one of them 2 inches long. The intestine is 14 inches long, its
diameter 1 1/2 twelfths. The coeca are 2 twelfths long, nearly 1 twelfth in
diameter.
The trachea is 2 inches and 4 twelfths long, its diameter 2 twelfths at the
top, diminishing to 1 twelfth; its rings about 105, unossified; its lateral
muscles moderate, as are the sterno-tracheal, and single pair of inferior
laryngeal. The bronchial half-rings about 25.
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