32 J. E. LTTTLEBOT — THE MIGRATION OF BIEDS. 



can hardly fail to have observed the marvellous regularity with 

 which migratory birds return to the localities in which they were 

 reared. That universal favourite, the nightingale, not only fre- 

 quents the same districts, but year after year pours forth from the 

 same trees, and often from the very same boughs, the matchless 

 music which we all love to listen to. I am informed by Mr. Geary 

 that nightingales have frequented a particular ti'ee in his garden at 

 Westwood, without a single exception, for the last forty years. 

 House-martins regularly build their comfortable nests against the 

 same eaves and in precisely the same spot. Last summer I counted 

 thirty-four nests on one small cottage in the village of Aldbury ; 

 the occupant told me that he was very fond of the birds, that he 

 never allowed them to be disturbed, and that he always had as many 

 nests as they could find room to build. Swallows frequent the 

 same chimneys and warblers the same copses. It would be easy 

 indefinitely to prolong the catalogue, but I prefer to quote a few 

 lines from the pages of ' Scribner's Magazine ' * in which incidents 

 of kindred character are recorded as occurring on the American 

 Continent. " Colonies of herons resort from time immemorial to 

 the same swamps, and even the same trees, to rear their young. 

 Terns, gulls, cormorants, and other water-fowl in like manner 

 repair to the same stretch of sandy beach, or to the same cliffs, 

 and only abandon them for more secure retreats after a long period 

 of ceaseless persecution from human foes. Many, it is believed 

 most, other birds return year after year to the same tree or to the 

 same immediate locality to nest." 



These facts become still more significant if contrasted with the 

 habit of migrants when retiring into winter quarters. They appear 

 to winter wherever shelter and food are found to be available, with 

 but little reference to the particular localities visited in pre\4ous 

 years. 1 have alluded to the wide geographical area that is frequently 

 covered by the migration of a particular species ; when viewed in the 

 light of the foregoing interesting statements, the reason for such an 

 occurrence is sufficiently obvious. Notwithstanding all that is so 

 frequently written respecting the wonderful instinct of birds, it is 

 certain that they lose their way very frequently, and in this manner 

 stray colonies are continually forming ; the young of the first year 

 returning to the locality of their birth, as parent birds, the year 

 following. 



It is time that I attempted to arrive at some definite conclusion. 

 I have endeavoured to demonstrate that neither the demands of 

 appetite nor the exigencies of incubation, when taken separately and 

 alone, can account, in a satisfactory manner, for the varied pheno- 

 mena connected with migration ; but they are without doubt im- 

 portant factors in the argument, and must always be comprised 

 among the essential conditions that help to constitute the " Natural 

 Home " of migrants. In order to formulate a theory, I pro- 

 pose to group both of these agencies, together with a third — 



* October, 1881, p. 935. 



