108 THE BIRDS OF HELIGOLAND 



acquainted are those of Richard's Pipit and the solitary examples 

 of the Tawny Pipit (Anthus campestris), which occur here at the 

 end of August. Solitary old birds of the Knot and the Sanderling, 

 in the stage preceding the winter moult, likewise occur here during 

 August. These however I regard as individuals who have 

 altogether failed to visit their breeding stations in the course of 

 the summer, and hence do not occupy a normal position hi the 

 migratory process generally. 



In the retarded autumn moult of these old breeding birds we 

 have in fact the cause of their delayed migration. They only 

 begin to moult after they have done rearing their young, by which 

 time the latter have their organs of flight so far developed as to be 

 almost, if not completely, capable of undertaking their first autumn 

 migration. Their parents, on the other hand, are obliged to tarry 

 in their summer quarters until their new plumage also has been 

 completed. 



In regard to the difference of the time of migration of young 

 and old birds, I may be allowed to add a few remarks from an 

 excellent book, viz. Rodd's Birds of Cornwall and the Scilly 

 Islands. Speaking of the Knot, the author, in the work in 

 question, states as follows, on p. 101 : ' I have also noticed that the 

 first flocks of these migratory Sandpipers, which usually arrive about 

 the second week of August, are almost entirely composed of young 

 birds. The old birds arrive somewhat later.' In regard to the 

 Woodcock, the same work contains (Introduction, p. xv.) a passage 

 from an essay of the Hon. Francis Roberts, printed in London in 

 1708, which, though not written with the object of proving the 

 difference of the time of migration of old and young birds, never- 

 theless fulfils this purpose in an admirable manner. The passage 

 in question runs as follows : ' When it first comes its flesh is short 

 and tender, whereas afterwards it eats stringy, and of a fibrous flesh, 

 as others of our fowls are/ This interesting observation, made 

 one hundred and eighty years ago, gives the clearest evidence of 

 the earlier migration of young birds as compared with that of their 

 parents ; for it is evident that by birds of short and tender flesh we 

 must understand the young ones, while, under stringy and fibrous, 

 the old ones are naturally indicated. 



The extracts from my ornithological journal, as given above, 

 besides the observations of other ornithologists here cited, to each 

 of which sources of information much further material might be 

 added, should suffice to establish beyond any doubt what has been 

 said as to the difference of time of the autumn migration of young 

 and old birds. It is however impossible that the phenomena as 

 observed in Heligoland should be limited exclusively to this island. 



