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‘Too many facts are directly at variance with this assumption. One 
of the most salient only—that of the flight of Richard’s Pipit may 
‘be cited here—* A bird whose breeding home is further removed 
from Heligoland than that of any other of its numerous visitors. 
A mere surface glance at the map shows in the most striking 
manner how many large rivers, in addition to the Ural chain of 
mountains, this bird has to cross, almost at right angles, in the 
course of its journey from beyond Lake Baikal te Heligoland 
every autumn.’’ The main direction of migration flight over 
Heligoland is in the autumn, from east to west, and in spring from 
west to east. In the chapter on the altitude of the migration 
flight, Gitke says, ‘*As long as migration proceeds under its 
normal conditions this elevation is; in the case of by far the larger 
number, so great as to be completely beyond the powers of human 
“observation; while we must regard as disturbances and irregu- 
larities of the migration movement proper, due to meteorological 
influences, such portions of it as are brought within our notice.’ 
He considers that migration proper proceeds at unknown heights 
with a tremendous velocity, and for the most part during the dark 
hours of night. Asa proof of the height birds can fly, Gatke 
mentions that Humboldt on the Andes saw condors flying at @ 
height of from 20,000 to 80,000 feet, or even 40,000. Three 
birds are named as often migrating only a few hundred feet above 
the level of the sea—the hooded crow, starling and lark. But he 
is strongly of opinion that most birds migrate at a height at 
which they are invisible. The weather exercises a great influence 
‘on the height of migration. On a dark night, with a uniformly 
‘clouded sky, 15,000 larks were caught in three hours, but directly 
the moon rose the island became completely Clear of birds, which 
immediately flew at a much higher level. 
In estimating the velocity of migration flight, Gitke says:— 
My own studies on this subject have yielded results which, in 
the most surprising manner, surpass all that has been said by Van 
Middendorf and other writers. Even in the case of so apparently 
sluggish a flyer as the hooded crow, which it would be ridiculous 
‘to enter in a match against a carrier pigeon, a speed of migration 
flight of no less than 108 geographical miles per hour has been 
established. The little northern blue throat is proved to be 
capable of flying 180 geographical miles per hour. It winters in 
‘Central Africa, and breeds in about 54 degrees north latitude, and 
‘does not stop at all on its way until it reaches Heligoland at about 
sunrise. Gitke considers that the Virginian plover, in flying from 
Labrador to Northern Brazil, crosses 8,200 geographical miles in 
15 hours, at one flight, i.e. 212 miles per hour. In further proof 
of speed, Gatke says, * Plovers, curlews, and godwits flying across 
