90 BOARD OF AGRICULTURE. [Jan., 



and poor from their summer's work of rearing tlie young. In 

 either case they eat heartily all they can contain. The insectivor- 

 ous birds find the insects just hatching from their chrysalids in the 

 spring, while in the fall they are in the act of turning; in either 

 case the birds find out these enemies to man, and attack them 

 ravenously. Tn the fall the seed-eaters act as gleaners, and glean 

 the fields, the trees, and vegetation generally, of the grain which 

 often has fallen from the stalk, having died from the ravages of 

 insects, and often containing, at the time, the egg or pupa of the 

 pest. In the spring the gleaners proceed to finish the work begun 

 in the fall; so that it is safe to say that millions of the injurious 

 pests are gotten rid of in this way. Moreover, the birds, in a sort 

 of way, seem to strive to so regulate their migrations that the time 

 of the year will be the same with them wherever they are; that is, 

 starting say from northern Maine, where the majority have passed 

 the summer in rearing their young, they progress westward and 

 southward, as the fierce arctic weather presses them, so that they 

 are continually in the region of late summer or early fall, in 

 Florida, Louisiana, and other of their homes and haunts. In the 

 spring they return in reverse order. 



Birds migrate for at least two reasons; the first, though we can 

 hardly call it autoviatic, is yet more or less mechanical, and occa- 

 sioned more or less directly by the weather; the other, we will briefly 

 state, as impelled by lack of their peculiar and specific diet. I 

 say specific, meaning it in the sense that the migration of different 

 species are at different times, since the food of each species differs 

 more or less in its time of appearance; the fact being proven, with 

 but little doubt, that the time of the appearing of the insect that 

 is the chosen food of any species of bird is the same time at which 

 that bird appears, both in the same locality. If, then, a bird's only 

 occupation was securing enough to eat, the following of that occu- 

 pation would answer all inquiries as to the causes of its migration, 

 on the ground of variation of season alone. Unfortunately this 

 explains but part of the question. Still, we have not reached our 

 final question, but are rather laying out the ground and sifting the 

 material that we may the better determine our results. 



Now it is well known that the robin congregates in large flocks 

 before finally leaving for its southern and southwestern home, yet 

 it confines itself to the woods and fields at such times, where it 

 undoubtedly does immense good in gathering insects and grubs, as 



