14 COLIN CLOUT'S CALENDAR. 



What marvellous complexity of interaction and mutual 

 relations between all the parts of nature and organic life 

 this familiar fact of the swallows' yearly return implies 

 for us ! Hard-billed seed-eating and berry-eating birds, 

 or mixed seed-eaters and insect-eaters, can manage to 

 find food for themselves in England all the year round. 

 Kay, even those species which live mainly upon worms, 

 slugs, and other hardy small deer, can pick up a living 

 somehow or other through our northern winters. But 

 pure fly-catchers, like the swallows, must starve during 

 the five months when winged insects are almost wholly 

 lacking in temperate climates. Thus it becomes a mat- 

 ter of necessity with them to move south at the begin- 

 ning of autumn, toward the orange groves of Italy and 

 the palms of Africa. Before they can return, there 

 must be insects in the north ; and these insects must have 

 been hatched from the egg, and re-hatched from the 

 chrysalis stage, before they are fitted to become food for 

 swallows, since swallows feed only on the wing. Ac^ 

 cordingly, it is not until the spring flowers are well out, 

 and the winged insects have begun to suck their honey, 

 that the various species of the swallow family make their 

 appearance. 



The true swallows come first, and, taking one year 

 with another, the second week of April may be taken as 

 the average date of their return to the south-western 

 counties of England ; but this year the spring, in spite 

 of its early promise, has hung fire a little in a curious 

 half -hesitating way ; and so I have not seen the first 

 swallow till this morning. The swifts, larger and 

 stronger birds, which fly even more incessantly than 

 their cousins and therefore require a more abundant 

 food-supply, do not usually come northward till the be- 

 ginning of May, when the flowers and insects are in full 



