278 GENERAL SCIENCE 



either in flocks or in small groups. Few of them will be 

 found in their usual haunts following one of these migra- 

 tions. These journeys in many cases extend over distances 

 of hundreds and hundreds of miles, and often are over vast 

 stretches of water as well as of land. How birds can be so 

 sure of their course, and how it is that they return as they 

 oftentimes do season after season to the same places of abode, 

 is again occasion for wonderment. 



The skill shown by each successive generation of birds in 

 nest building is another evidence of their superior intelligence. 

 This is commonly referred to though not explained by calling 

 it instinct. The manner of nesting is characteristic of the 

 bird, and the nest serves to identify its builder. A pair of 

 young birds building their first nest construct it as other 

 birds of that species have done before them. This remains 

 true even where young birds have been reared wholly apart 

 from their kind. Some birds build nests which are marvels 

 of ingenuity and skill in construction. Their selection of a 

 place for the nest often exhibits the greatest cunning. Many 

 stories are told of the deception and thievery practised by 

 the crow when captured young and tamed at some farm 

 home. Some parrots when trained show a marvelous degree 

 of intelligence. 



Birds feed very largely upon weed seeds, and upon insects. 

 The young are fed insects and worms quite exclusively for 

 the first few weeks. Many species of birds live almost 

 wholly upon insects when obtainable, using fruits and seeds 

 only when the other foods fail. The value of birds to man 

 may be calculated not in the number of insects actually 

 destroyed for food during the whole season but in the number 

 which would otherwise have multiplied from those destroyed. 

 The value of birds to man in holding in check insect pests 

 and weed growths is greatly underestimated. The horti- 

 culturist is unable to raise marketable fruit without con- 



