observed at lite Kentish Knock Lightship. 123 



great diurnal movements I have endeavoured to describe, 

 Swallows and Martins in considerable and Wheatears in 

 lesser numbers were also observed moving westwards. The 

 fact that these species proceed along this route in autumn 

 is the clearest possible evidence, if such were necessary, that 

 it is also a true passage fly-line for emigrants proceeding 

 from the Continent to their winter-quarters south of the 

 British Isles. These birds of passage after arriving in South- 

 eastern England sooner or later take their departure from 

 our southern shores, en route for Africa in some cases and 

 South-western Europe in others. On some occasions small 

 numbers of all the species mentioned as migrating from E. 

 to W. were observed proceeding from S.E. to N.W., hut this 

 was exceptional and the movements were never important. 



It will have been noticed that the species recorded as 

 participating in these great E. to W. movements are com- 

 paratively few in number. This, I think, may be accounted 

 for by the fact that at present our knowledge regarding them 

 is practically confined to what has been observed during the 

 day-time. At the Eddystone, likewise, a few species only 

 crossed the Channel by day, but in great variety at night. 

 May not the same be the case at the Kentish Knock ? I am 

 inclined to think that we have here the true explanation ol 

 the situation. The phenomena of migration as witnessed 

 at this station are, however, exceedingly complicated, as 

 has already been stated, and it was found impossible to 

 determine from actual observation whence came the birds 

 that were so abundantly noticed during the hours of darkness. 

 I shall return to this subject anon when discussing the night- 

 movements. 



The reason why the movements of these species are per- 

 formed so largely during the day-time, instead of entirely at 

 night as in the case of most over-sea migrations, appears to 

 me to be due to the comparative shortness of the passage. 

 The few hours necessary for its accomplishment would not 

 interfere unduly with the time that must be devoted to the 

 daily search for food — a most important consideration for 

 all migrating birds. 



