186 THE BIEDS OF HELIGOLAND 



stance with so much opposition, that, in order to allay all doubts 

 on the matter, I, one calm sunny day towards the end of September, 

 at noon, fixed my eyes on one particular individual of the large 

 number of departing Buzzards without letting the bird pass out 

 of my sight as long as I was able to distinguish it in the clear sky. 

 When it had reached a height of about 400 feet it lazily flapped 

 its wings two or three times, and then spreading them out soared 

 upwards, without moving its wings, until it disappeared from view. 

 This, according to a reliable estimation, must have occurred at a 

 height of from 12,000 to 15,000 feet. I base my estimate of this 

 height on the migratory flights of the Hooded Crows which pass 

 every autumn across Heligoland or along its shores. Among the 

 flocks of these birds as they fly round the extreme southern point 

 of Sandy Island a distance of about 8000 feet a keen eye can 

 still distinguish every individual bird. Hence the height of the 

 above-mentioned Buzzard, seen from below in the whole expanse 

 of its wings, has certainly not been exaggerated. These Buzzards 

 are frequently accompanied by the Common Kestrel, as was also 

 the case in the present instance. The Kestrel, however, rises 

 upward in a manner quite different from that of the Buzzard, 

 for it careers in circles round the latter, its flight in this way 

 assuming a spiral course. It is indeed a very pleasing sight to 

 behold this small Falcon, with oft-repeated hasty strokes of the 

 wings, following in faithful attendance the large Buzzard as the 

 latter soars calmly upwards to the heights above. 



Evidently the Kestrel is not equipped for a soaring flight like 

 the Buzzard, for, in order to perform its spiral upward revolutions, 

 it is obliged from time to time to execute ten or twelve rapid and 

 powerful strokes of its wings, which enable it, in virtue of the speed 

 thus acquired, to describe a half or complete circle on calmly 

 expanded pinions. The only investigator who, as the result of his 

 own multiplied observations, confirmed my reports as given above, 

 was Dr. A. Walter, an observer whose early death is a deplorable 

 loss to science. I happened, during a discussion I had with him 

 on the different phases of migration, to make mention of this par- 

 ticular subject, when he at once interrupted me, confirming my 

 statement, and further mentioned his own observations as to the 

 part of companion-migrant played by the Kestrel, though I had not 

 yet alluded to that circumstance. In his own home Livonia 

 he had often, during the shooting season, observed with great delight 

 the peculiar social journey of these two feathered plunderers. 



How the Buzzard is able, in an atmosphere so much lighter 

 specifically than its own body, to soar upwards like a balloon, with- 

 out the mechanical aid of its wings, and without being renderec 



