410 THE BIRDS OF HELIGOLAND 



'kiitt kiitt kiitt.' Since, however, they get no reply, nor espy any 

 tree to their liking, they soon continue their journey onward. 



That birds are able to discern from a great distance, or an im- 

 mense height, whether a particular place offers them the requisite 

 conditions of rest and nourishment, is well illustrated by the following 

 instance : A vessel laden with provisions for the winter which was 

 returning home from the mainland, ran ashore on Sandy Island 

 and went to pieces. A number of quarters of beef, forming part of 

 its cargo the meat being perfectly fresh were lying about on the 

 shore of the sandbank, and forthwith attracted the notice of the 

 Common Raven by the promise of a good feast ; this bird, however, 

 is of so exceptional occurrence here that it has only been seen on 

 three occasions during the last fifty years. 



In support of the above opinion, written down from six to eight 

 years ago, a proof has recently been furnished by this species of 

 Crossbill. In 1887 this bird appeared as early as June and July in 

 flights which frequently summed up to a hundred individuals ; all 

 of them, almost without exception, resorted to the thorns in my 

 garden, which are from fifteen to twenty feet in height, where they 

 pecked about actively among the leaves. As I felt sure that the 

 leaves alone could not form the food of these birds, I examined 

 them, and found that each leaf, which was more or less curled up, 

 contained a small white hairless caterpillar, and these larvae were 

 also found filling the stomach of such of the birds as had been 

 shot. The birds must consequently have observed, in their flight 

 across the island, that this by the way, quite unusual kind of food 

 was present in exceptional abundance. On turning up Naumann, I 

 find under article ' Food,' that these Crossbills will also eat plant lice 

 (aphides) ; the poplars formerly abundant here always had a large 

 quantity of leaves with large blisters or swellings on their upper 

 surface, which were thickly crowded with plant lice ; hence it was 

 doubtless these insects which at that time enticed the birds to 

 alight on the island. 



Amongst the numerous flocks of the Common Crossbills which 

 came to this island about forty years ago, there occurred a fairly large 

 number of individuals in which the greater and intermediate outer 

 wing-coverts had white terminal spots constituting two more or 

 less pure white bars across the wings, like those shown in the repre- 

 sentation of the young bird in Naumann (PI. 110, fig. 4). These bars 

 were never broader than those in the figure in question, but for the 

 most part narrower, frequently merely forming a fine white line. I 

 have handled many examples of this kind in all stages of age, but 

 have only one old red bird with this kind of marking in my collec- 

 tions. We cannot look upon such individuals as transitional forms 



