473 
1921 .] Bird-Migration by the Marking Method . 
marked birds are 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 / 6 th 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 feet 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, 10, 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 ma} r , 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. 
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