41 
probably far greater than is usually thought. Swallows and 
swifts will soar very high just previous to their departure; and 
migratory birds will drop perpendicularly from the sky with start. 
ling suddenness when their flight is arrested by change of weather, 
Migrants scarcely ever strike lighthouses and the like, excepting 
during sudden darkness from fog or clouds. Birds may be actually 
observed migrating as high as they are visible. Gitke mentions 
rooks on passage so high that they looked like dust, and were only 
recognized by their cries. Mr. Dixon thinks the greatest gain of 
this high altitude is the increased expanse of the earth that is 
yisible; but as most migration is at night this seems doubtful, 
Another possible advantage of which Herr Gitke takes more 
notice is the diminished resistance of the air at great height, and 
consequently less impediment to great speed, and diminished 
fatigue. The currents of air at a great altitude may also be more 
uniform and favourable, and there may be a greater immunity from 
enemies. Some species of birds are very noisy during their 
flight, keeping up quite a chorus of cries. Often in the early 
autumn have I heard them passing over Folkestone at about 10 or 
11 p.m., the cries being usually those of the wader family. Crows 
travel silently, larks are incessantly calling to one another. 
Migration is much interfered with by storms. The most favourable 
wind for this part of Europe seems to be a §.E. wind for birds 
flying 8. or E., and not a wind blowing directly behind them. A 
_ great deal has been written about the various routes of migration, 
and Mr. Dixon says ‘The great routes of migration, whether over 
land or sea, are closely connected with the configuration of the 
arth’s surface. We may, for the sake of convenience, divide them 
into four very marked classes, viz., sea routes, coast routes, 
mountain routes, and river or valley routes.” On this matter, 
later on, I will read to you what Herr Gatke says. The perils of 
migration are both numerous and deadly, and due partly to fatigue, 
partly to the natural enemies each species meets with on its 
journey, and partly to blunders on the way, and accidents, such as 
gales and storms. Some ornithologists think that the mortality 
list of migration is more than 50 per cent., and of those that 
perish, it is thought that more than half perish at sea. Instances 
are on record of great numbers of drowned migratory birds being 
‘washed ashore, especially after stormy weather. Tired birds will 
settle on the sails and decks of vessels in the Atlantic, or in the 
middle of the Mediterranean. Water rails, sandpipers, and cross- 
bills have flown on board a vessel more than 1000 miles from land. 
Dixon mentions the arrival of flocks of golden crested wrens on 
the east coast of England after a stormy passage. He says 
4‘ Before sunrise on the chilly late October mornings, I have seen 
