The SAND MARTIN (_Cotyle riparia_), one of the smallest members of its
family, is only five inches long and eleven broad; the wing measures
four, and the tail two inches. The plumage is greyish brown above, white
beneath, and marked on the breast with a greyish brown ring. The sexes
are nearly alike, but the young are darker than the adults. These birds
inhabit and breed in all parts of Europe, except the extreme northern
countries, and usually frequent such rocks or hills as overhang streams
and rivers. The wonderful nests that have rendered the members of
this group so famous, are made either in natural hollows, or in holes
excavated with enormous labour by the builders; they appear, however,
to prefer the cavities which they have themselves prepared, and are
most careful to dig their retreats at such an elevation as to be above
high-water mark. "It appears," says Naumann, "almost incredible that
a pair of these small birds, with no other instruments than their
delicate beaks, can dig, as they do, a horizontal passage several inches
in diameter, and from three to six feet deep, in the space of two, or
sometimes three days. The male and female both assist in this, for
them, gigantic undertaking, and work with the utmost energy and ardour,
disposing of the loose earth by throwing it out behind them with their
feet; and yet, strange to say, it is not uncommon for them suddenly
to leave one of these excavations when almost finished, and commence
another; occasionally, they will even dig a third. Why they do this
has never been satisfactorily ascertained, for it is only the passage
to the chamber in which the nest is made that is ever occupied either
by the parents or the young family. Many pairs invariably work close
together, thus forming an extensive settlement, and it is most amusing to
watch the earth flying out of a number of their holes as it is ejected
by the busy labourers, who are usually quite out of sight." It is to
these settlements that Pliny alludes in the following amusing terms:
"At the Heracleotic mouth of the Nile in Egypt, the Swallows present an
insuperable obstacle to the inroads of that river, by the embankment
formed by their nests in one continuous line, nearly a stadium in
length--a thing that could not possibly have been effected by the agency
of man. In Egypt, too, near the city of Coptos, there is an island sacred
to Isis; in the early days of spring, the Swallows strengthen the angular
corner of this island with chaff and straw, thus fortifying it in order
that the river may not sweep it away. This work they persevere in for
three days and nights together, with such unremitting labour that it is a
well-known fact that many of them die in consequence of their exertions;
moreover, this is a toil which recurs to them regularly every year."
The nest itself is made at the end of the above-mentioned passage, and
consists of a bed of straw, hay, and fibres, snugly lined with wool,
hair, and feathers. The eggs, five or six in number, are of an oval
shape, and have a thin, pure white shell. The young are hatched in a
fortnight, and remain for a similar period under the care of their
parents. Should the first family not be reared, a second brood is at once
laid. The flight of the Sand Martin is so light as to bear comparison
with that of the butterfly. Its voice is weak and gentle, and its
disposition lively and active; it is extremely social, and lives at peace
with most other birds. In its general habits it resembles its congeners,
but leaves for warmer climes earlier in the year than they do, and does
not reappear till about May.