50 
Introduction: Migration. 
Brewer and Eidgway’s “Water Birds of North America” 1884 I, 123, whether 
those birds which spend the summer in the winter haunts of their species are 
not old, effete and barren individuals. This suggestion is negatived by the 
fact that among such visitors to Celebes five species have been known 
to breed in some part, or ]3arts, of their winter range, viz. Charadrius fulmis^ 
Aegialitis geoffroyi^ A. mongola, Strepsilas interpres and "Limosa novaezealandiae. 
Causes of migration. - — It may be tritely said that birds migrate in autumn 
to feed, in spring to breed! At the approach of winter most birds must of 
necessity proceed towards the tropics, or starve, owing to the disappearance of 
their food through death or hibernation, or through concealment under snow or 
ice. In spring the temperate and arctic regions produce an abundance of food 
and, it may be presumed, offer safer and easier conditions for the propagation 
of the species than is found in the tropics; the birds then repair to their native 
haunts. Naturalists, who seek for physiological conditions to account for the 
actions of the subject, may find a stimulus for the spring migration in the annual 
development of the reproductive systems, while the approaching autumnal moult 
of the remiges may sometimes serve as a warning to species that it is time to 
accomplish their flight towards the equator, for many of them leave long before 
the cold sets in. Waders killed in their winter quarters in the Celebesian area 
in the late autumn or winter months are generally found to be moulting some 
of their remiges. Possibly, however, the chief motive for the spring migration 
is to be found in the love of home so strongly developed in birds, for without 
this it is conceivable that they would attempt to establish themselves in the 
tropics for breeding purposes. Instances of the marvellous regularity with which 
individuals return to the old breeding haunt after a journey of hundreds, or 
more often thousands, of miles have excited the admiration of all field-observers. 
That the young birds also sometimes follow their parents to their birth-place is 
shown by a case given on p. 48 (text). But it seems to be the case — which is 
not so generally known — that birds display a very similar adhesiveness in the 
choice of their winter quarters. An instance of enormous numbers of Wagtails and 
Swallows returning two years in succession to roost in a coffee garden in Ceylon, 
as observed by Mr. S. Bligh, will he found on p. 537; and Davison states 
that a large number of migratory Collocaliae., which had taken to roosting upon 
a certain spot about a yard square against the roof of a shed in the Andamans, 
disappeared when the building was pulled down, only to come again and occupy 
the same spot on a new shed, which had been put up on the identical site 
(p. 332). There are no rookeries near Dresden, but every year about the be- 
ginning of November great numbers of Books and Jackdaws pass over the 
neighbourhood for many days in succession'), and some spend the winter there. 
1) The flocks fly high, so that it is sometimes difficult to detect them with the naked eye. The mode 
of progress is very slow in a S. or S.W. direction, perhaps at the rate of 12 miles an hour, and conducted 
with much cawing and calling and circling in the air, as if none wish to have the responsibility of leading the way. 
