1 92 1.] Bird-Migration hy the Marking Method. 473 



marked birds arc reported as found dead or wounded, or as 

 captured and subsequently released. 



The question as to whether the rings have a harmful or 

 disturbing effect on the birds has also been raised. It must 

 be remembered, however, that the ring rests lightly on the 

 insensitive scales of the foot, and is insignificant in weight 

 compared with the size of the bird ; the writer's smallest 

 ring, suitable for Sparrows, weighed only about 1/Gth of a 

 gramme, and his largest, for Herons, only about 1 gramme 

 (average). A newly marked bird pays little or no attention 

 to the ring, and out of a large number of ringed f(?et returned 

 to the writer for examination only two or three showed any 

 signs of injury, due in these cases to the use of a wrong size 

 of ring by the marker. The migrational habit might pre- 

 sumably be interfered with in cases where a large mass of 

 weeds or other matter became firmly entangled with the 

 ring — no case of this kind has been reported, — but undue 

 stress can, in any event, never be laid on any isolated record. 



The device of marking birds in some way was not infre- 

 quently resorted to, in isolated cases and for special purposes, 

 by naturalists of earlier days, and one often comes across 

 stray records. But, so far as the writer is aware, it was not 

 until 1890 that the first systematic scheme was set on foot. 

 In that and many subsequent summers, numbers of young 

 Woodcock were marked on the Duke of Northumberland's 

 estate at Alnwick (14). The rings were inscribed with an 

 "N," and the date (year). 



In 1899, Mr. H. Chr. C. Mortensen, of Viborg, Denmark 

 (9, lOj 11, 12, 13), started a more ambitious inquiry, and the 

 Stork, the Heron, the Teal, and the Starling are among 

 the species which he has studied by this method. Mr. Mor- 

 tensen may, indeed, be regarded as the pioneer of scientific 

 bird- marking, because his inquiry was the first which was 

 thoroughly comprehensive in scope and exact in methods : 

 the use of identification numbers instead of mere year figures 

 was a good innovation which opened up many fresh possi- 

 bilities, although at the same time involving much more 

 labour in the way of record-keeping. 



2i2 



