VELOCITY OF THE MIGRATION FLIGHT 65 



undoubtedly are, as is proved by an actual performance of this 

 nature, which surpasses all that has been stated hitherto. Strange 

 to say, the feat in question was not performed by a member of any 

 of the species enumerated above as excellent flyers, but by a little 

 bird which one would certainly not have regarded as endowed with 

 more than moderate powers of flight to wit, the Northern Blue- 

 throat. Nevertheless, this little bird proved to be capable of flying, 

 during its migrations, at the rate of one hundred and eighty 

 geographical miles per hour. 



An extraordinary velocity of this kind is specially developed 

 during the spring migration. The time occupied in the latter 

 movement must of necessity be as short as possible, for many 

 birds, more especially species from high northern latitudes, have 

 but a very short span of time allotted to them for the building of 

 their nests, and the breeding and rearing of their young. Accord- 

 ingly the majority under normal conditions, and in the absence 

 of meteorological influences of a disturbing nature, accomplish 

 their migration in one uninterrupted nocturnal flight. It has 

 thus been shown that species, like the Northern Bluethroat 

 already referred to, which winter in the Nile districts and in 

 Central Africa, from about 10 to 27 N. latitude, extend their 

 flight thence in the course of one single spring night, up to 54 N. 

 latitude, and, doubtless, even considerably farther thus accom- 

 plishing a distance of at least 1600 geographical miles within the 

 space of nine hours. 



The Northern Bluethroat leaves its winter quarters for its 

 northern breeding home at ihe end of April or beginning of May, 

 and Heligoland is the first point at which, in the course of this 

 journey, it is met with unfailingly every year in very large numbers 

 under favourable conditions of weather. In all intermediate 

 latitudes Greece, Italy, South Germany, and even in the neigh- 

 bouring parts of North Germany it is at this time so rare an 

 occurrence that its appearance in any of these districts may be 

 regarded as an extremely exceptional accident, or, in the words of 

 Naumann, vol. xiii., as ' very isolated and rare.' 



In Heligoland, on the other hand, it is not at all unusual to 

 obtain from twenty to fifty of these birds on one day, in fact, 

 I remember having on one occasion some sixty specially-selected 

 beautiful males brought me one May morning, while the brothers 

 Aeuckens obtained an almost equal number. All such birds are 

 caught in the gardens of the Highland (Oberland), while equally 

 large quantities frequent the rubble and the natural grottos at the 

 base of the clifF, and the bushes of the Dune island. 



Like most birds, especially insectivorous species, the Northern 



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