XIV MIGRATION 349 
fifty years watching the mighty stream of migrants 
that passes to and fro. All the Heligolanders have 
helped him, bringing every specimen they could obtain 
that was rare enough to be worth looking at. And 
every one in the island turns out for the dattue, with 
a far too slaughterous zeal, when the flocks of migrants 
descend upon it. Sometimes such clouds of birds 
appear that they cover every square foot of ground 
upon the island. The most striking of the recorded 
flights took place in October 1882, when for three 
successive nights there were thick masses of migrating 
Goldcrests, beating thick as snowflakes against the 
lighthouse. But these represented only a small frac. 
tion of their numbers, for the front of the advancing 
host extended from the Shetlands to Guernsey, and 
probably even further south. Living thus on his islet, 
the ways of migrants as familiar to him as the beat of 
the waves, Herr Gatke has been able to give a 
life and interest to his book that no writer on the 
subject who has gained his knowledge only by reading, 
or who has caught only occasional glimpses of the 
great movement, can possibly rival. And though he 
has seen so much, he has never failed to realise the fact 
that what he has seen is much less than what has 
passed beyond his ken, or been only dimly descried, 
that the birds which have flown over Heligoland, often 
far too high for the reach of the human eye, are far 
more numerous than those which stress of weather, or 
whatever circumstance, has led to settle on the island. 
Unfortunately Herr Gatke’s work has not been trans- 
lated into English, but it should be read by every 
lover of birds who is tolerably familiar with German, 
