THE BIRDS OF HELIGOLAND 229 



they arrived as early as the 15th of the month, but usually they do 

 not reach here until the 20th; from that date their number 

 increases daily for three or four weeks, and the migration terminates 

 with the end of July. The conditions requisite for the migration 

 of these young birds are line warm weather and a south-east wind. 

 The summer of 1878 proves in what vast quantities they may 

 arrive under such conditions. Thus my diary has the following 

 entries : June 20 and 21, great flocks of young Starlings ; June 22, 

 23, 24, enormous numbers of young Starlings ; until the end of the 

 month many thousands daily wind south-east, weather calm, 

 clear, and hot ; July 1st to 12th, young Starlings in thousands and 

 tens of thousands every day never seen here in such large quan- 

 tities before ; until the 16th, daily flocks of hundreds of individuals ; 

 on the 25th again, large numbers of young birds, with which the 

 migration of the young grey-plumaged birds came to an end. 



There now follows an interval of tAvo months during which no 

 Starling is seen. At its termination commences the migration of 

 the old birds which have completed their moult, being now arrayed 

 in their black and much-spotted livery. In the above-named year, 

 1878, the first flocks, counting by hundreds, arrived on the 22nd of 

 September. My further entries are as follows : On 2nd and 7th of 

 October, large flocks of old birds ; on the 8th, flocks of thousands ; 

 on the 13th, Hooded Crows and old Starlings in tens of thousands ; 

 on the 14th, many thousands of Hooded Crows, and old Starlings in 

 hundreds of thousands; on the 15th, large numbers of Starlings; 

 on the 16th, few ; on the 20th, tens of thousands ; on the 28th, large 

 numbers. November 18th and 19th, flights of from twenty to fifty ; 

 December 9th to 18th, flights of from forty to sixty individuals. 

 With these the autumn migration of that year terminated. Year 

 after year the migration proceeds on the same enormous scale, 

 defying any attempt at an actual estimate of the numbers of 

 individuals engaged therein, in fact, in my diary I have frequently 

 found the term ' clouds of migrants ' as alone capable of conveying 

 an adequate impression of these enormous, almost endless flocks, 

 as they rush in a densely crowded horde across this island. 



After what has been stated above, it will hardly be necessary to 

 further point out that no other species proves in a more striking 

 manner how the young ' summer birds ' [i.e. birds of the year] 

 perform their migration independent of, and unattended by, the 

 parent birds ; for, on the one hand, the colours of the old and 

 young birds are so entirely different, that the age of the individuals 

 of a migratory flock can be told at once, and without any trouble, 

 even at a height of several hundred feet ; and, secondly, a great and 

 rigidly defined interval exists between the times of migration of the 



