48 



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 

 he 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 to 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, Gatke 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 

 i^ith a tremendous velocity, and for the most part during the dark 

 Tiours of night. As a proof of the height birds can fly, Gatke 

 mentions that Humboldt on the Andes saw condors flying at a 

 height of from 20,000 to 30,000 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 

 elouded 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, Gatke says; — 

 ^' My own studies on this subject have yielded results which, in 

 the most surprising manner, surpass all that has been said by Van 

 Hiddendorf and other writers. Even in the case of so apparently 

 sluggish a flyer as the hooded crow, which it would be ridieulous 

 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 

 <3entral Africa, and breeds in about 54 degrees north latitude, and 

 does not stop at all on its way until it reaches HeUgoland at about 

 sunrise. Gatke considers thai the Virginian plover, in flying from 

 Labrador to Northern Brazil, crosses 3,200 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 



