112 CASSELLS BOOK OF BIRDS. 



their native land throughout the entire year. In Egypt and South-western Asia they are replaced 

 by a smaller but very similar species. The Rock Swallows seldom associate with their congeners, 

 and are readily distinguished from them by their greyish hue, and comparatively slow and hovering 

 flight. In Switzerland, after their return in the spring, they usually allow some time to elapse before 

 they seek their own nests or build new ones ; during the interval they busy themselves in making 

 excursions in all directions, either skimming near the mountains, or, if the weather be fine, soaring 

 to a considerable height in the air. If, on the contrary, the season be dull or rainy, they keep 

 close to the earth, or beneath projecting rocks and stones. If the day be bright, they come down 

 from their retreats among the mountains, and perch upon the roofs of cottages, but never venture 

 actually into houses. The nest is placed beneath a projecting ledge of rock, or in some similar 

 situation, and resembles that of the Chimney Swallow. Several pairs frequently build together, but we 

 have never seen settlements like those formed by some other species. Many various statements have 

 been made as to their mode of nidification, seeing that, owing to the precipitous nature of the 

 localities selected, it is very often extremely difficult to approach the abode of a Rock Swallow. The 

 eggs are white, spotted with red, and are from three to five in number. After the nestlings are 

 fully fledged, they still remain for some time with the old birds, following them about in search 

 of insects, which are caught on the wing, but as soon as a fly or a beetle is thus obtained, the 

 hungry young perch for a moment upon a tree, and receive the morsel from the parent's beak. 

 When the period of incubation is over, the different families form small parties, and wander about 

 the country, as in the spring, until the proper time for commencing their migrations. In its general 

 disposition, the Rock Swallow is less alert and brisk than its congeners, and its voice has a deeper 

 and rather hoarse sound. 



THE SAND MARTIN. 



The Sand Martin (Cotyk riparid), 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 front 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 



