23 



of the Jay described elsewhere ; it seems impossible to realise 

 how so many of a rare species whose nesting stations must have 

 been scattered over a wide country can have come together 

 unless they had gradually concentrated themselves on to some 

 customary fly line. It may be surmised that many small flocks 

 had accumulated at some point where their further progress had 

 been delayed by unfavourable weather. Herr Gatke's description 

 of the flight seems to point to this — small parties at first, then 

 larger ones, then a steady stream of flocks, and lastly the main 

 body in one continuous procession. Had an advancing column 

 of Honey Buzzards in a rank corresponding to the latitudinal 

 area of the breeding range suddenly set out from the Asiatic 

 forests to Western Europe, gradually augmenting its numbers 

 as it progressed, it could hardly fail to have attracted notice in 

 many parts, whereas in the present instance, Heligoland seems 

 to have been almost the only spot where such large numbers 

 were observed. On the theory of a direct east to west migration 

 many of this throng should have reached the coasts of Great 

 Britain unless a southerly turn was made soon after passing the 

 island. In the former country, owing to the persecution meted 

 out to all the larger birds of prey and other rare species, an 

 event of this nature could hardly have failed to have excited 

 remark. We know what has happened during the visitations of 

 Pallas' Sand Grouse. 



If on the other hand these large flocks had become gradually 

 concentrated — through the configuration of the country, the 

 following of river valleys or shore lines — into a narrow stream 

 the chances of their escaping notice would have been vastly 

 increased, especially as their ultimate destination seems to have 

 been some part of North-Western Africa. It is well known that 

 the Honey Buzzard passes the Straits of Gibraltar in large 

 numbers every year (Irby). It is only evading the difficulty in 

 suggesting that a further westerly flight may have been con- 

 ducted at a great elevation and thus have escaped notice. It 

 has already been pointed out in the case of the Hooded Crow ; 

 that, such a change in altitude really means, according to the 

 author's theories, a sudden variation in meteorological conditions 

 necessitating an ascent to higher regions of the air. That in 



