MIGRATION OF SHORE-BIRDS 115 
fitted in general for a long flight than in the autumn, fewer 
individuals succumb to storms and exhaustion. Thus we do 
not hear so often in spring as in autumn of the finding 
of some species of migratory bird which has fallen exhausted 
to die. Birds migrate at night as well as day; thus, if a 
number pass over the observer without giving any call notes at 
night, nothing can be recorded of them if the night is dark. 
It often happens that spring migrants arrive at their breeding 
haunts some time during the night, and the first that is noted 
of them is that they are seen there by the observer on the 
following morning. This is particularly the case with our 
common summer visitor, the corncrake, or landrail. One 
seldom sees this bird arrive. He is, however, frequently shot 
on our shores at the time of his departure in the autumn. 
The distances traversed by some migratory birds are cer- 
tainly beyond the conception of man, as far'as how the journey 
is so accurately performed. We have birds visiting our islands 
on passage to and from the north every year. These creatures 
journey a distance nearly equal to that from the Equator to 
the Pole. Birds as a rule perform their spring migration 
much more quickly and with more punctuality than they do 
their autumnal. Many very sufficient reasons are advanced in 
support of this statement. In the case of tardy southward 
movements the birds may be waiting for the young to attain 
full growth and flight, etc. ; but it must not be supposed that 
this in all cases holds good, for swallows have been known to 
leave their young in the nest to perish rather than delay their 
southward movement. In spring the dates of arrival of 
familiar migrants can now, after our somewhat lengthy ex- 
perience and observations, be fixed with fair accuracy, and it 
is singular to find, despite the weather, that these birds arrive 
annually within a few days of their time. For seven years, 
during the first few days of May, I visited a certain grassy 
common where moor-dotterels halted for a brief period on 
