62 PASSE RES. 



from clime to clime in search of their insect food. When about 

 to remove to a country of more genial temperature, they collect 

 in immense flocks, and may be observed congregating upon trees, 

 or on the roofs of houses and other high buildings, before their de- 

 parture ; at other times they frequent the neighbourhood of lakes, 

 rivers, and ponds, over which they fly in small parties, skimming 

 rapidly in extensive sweeps near the surface of the water, and sud- 

 denly changing their course backwards and forwards, being all the 

 time busily engaged in capturing the insects upon which they live. 

 Sometimes they may be seen in the streets of towns, or ranging 



Fig. 31. — The Swallow {Hirundo rustica). 



over plains, fields, and gardens, while at intervals they repose, after 

 their exertions, upon the tops of buildings or upon the branches 

 of trees. Their nests are usually composed of clay or mud, mixed 

 up with straws. They are variously shaped, and generally attached 

 to the exterior of houses or in chimneys, or the interior of hollow 

 trees. Some species construct their nests in holes in the ground, 

 in which case they consist entirely of loose dry grass, lined with 

 feathers. The eggs are generally five or six in number. 



The migration of the swallows has now been set beyond a doubt 

 by actual observation, made both on our own shores and on those 

 of the Mediterranean, where they are seen taking their departure 

 for the warm regions of Africa in the autumn, and also making 



