INTRODUCTION. 



For further information on this subject see "the Appendix to Budc- 

 land's "Natural History of British Fishes" (S.P.C.K.), from which the 

 above details have been taken. The original article is, however, singularly 

 wanting in scientific precision. There is no statement of the time occu- 

 pied by the various stages of fish-hatching and rearing ; and although 

 great stress is laid on the necessity for keeping a daily register of the 

 temperature of the water, the temperature at which it should be kept is 

 not stated. All these are points on which careful observation is required 

 if fish-culture is to become a profitable industry. 



Migration of Birds. 



The migration of birds is chiefly a question of food supply, and it is 

 therefore correlated to insect and vegetable life, and through them to 

 meteorological conditions. It is not peculiar to either hemisphere, and 

 has no necessary relation to the physical disposition of land and water. 

 It is not confined to any family of birds, nor are all the individuals of one 

 species migratory or non-migratory. British birds may be divided into 

 four groups, according to the extent and nature of their migrations, 

 (i) Birds which spend the summer and breed in this country, such as the 

 swallow, nightingale, and the cuckoo, and which we are accustomed to 

 speak of as summer visitors, but which may be said to be native birds 

 which leave the country at the approach of winter. These birds have 

 long wings and soft beaks, and feed chiefly on mature insects ; they breed 

 in the coldest part of their migration, which in our hemisphere is the 

 most northern point. (2) Birds which have no fixed breeding-place and 

 winter wherever they may be driven, such as the fieldfare, redwing, wax- 

 wing, and a great variety of wildfowl. " These," says Mr. Seebohm, " will 

 always be found hovering on the outskirts of the frost. A heavy fall of 

 snow will drive them south, only to return the moment the weather 

 becomes less rigorous." (3) Birds which are true " birds of passage " 

 and simply traverse our country, or pass along our shores in the autumn 

 on their way to southern latitudes ; and in the spring on their return to 

 their northern breeding-places or " homes." Some of the routes of these 

 birds have been supposed to be" ancient coast-lines along which they 

 formerly used to travel ; others for generation after generation having 

 since followed the identical track although the land has long since dis- 

 appeared. (4) Birds which have no migratory instincts, such as the 

 sparrow, rook, and other thick-billed birds which live chiefly on seeds, 

 worms, and moluscs ; and the redbreast, hedge-sparrow, lark, and 

 golden-crested wren, with softer beaks, whose food consists principally of 

 the eggs and larvae of insects. Some of these birds, however, are driven 

 to or from our shores by stress of winter weather, and large flocks of 

 chaffinches, lafks, hedge-sparrows, jays, &c., are seen at various times in 

 the island of Heligoland and elsewhere, under, these conditions. 



The migrations of our summer birds, Mr. Seebohm tells us, take place 



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