1 921.] Bird-Mig7'ation by tlie Marking Metliod. 471 



Historical Survey of Bird-Marking, 



Various kinds of marks have been tried or suggested, such 

 as parchment tied under the tail with silk, thin metal discs 

 glued to the tail-feathers, and indelible stamps on the tail- 

 feathers. But all these, besides being clumsj', have the 

 great disadvantage of lasting only until the next moult, and 

 for both convenience and permanence marks on the feet are 

 obviously the best. In early, isolated attempts at marking, 

 such crude means as brass wire or silk thread twisted round 

 the bird's foot were used; but in order to allow of an 

 inscription, a broad metal ring is necessary. As combinino- 

 extreme lightness with a moderate degree of durability, 

 aluminium is to be preferred, and all the more because it is 

 easily worked and stamped. 



Complete rings, such as are used for homing-pigeons, are 

 of little use for marking wild birds, as they can only be 

 placed on very young birds in any case, and not even then 

 in the case of birds with nidifugous young, these having 

 well-grown feet by the time they are hatched. Furthermore, 

 these rings are expensive, as they are cut from aluminium 

 tubing instead of from sheet aluminium, and have to be 

 stamped when in circular shape instead of on the flat. 

 Hence the superiority in every way of the " split ring,'' 

 which is a band stamped from a sheet and then folded into 

 a circle. The edges are merely pressed together, and a ring 

 of this kind, if of small diameter, will keep its shape without 

 difficulty. Rings of larger size must either be of thicker 

 metal to do this, or must have a clasp of some kind. A very 

 simple pattern is one in which the band is longer, and is not 

 all used in forming the circle ; two unequal ends are left to 

 project outwards side by side at the meeting place, the longer 

 being afterwards folded over the shorter, and so forming a 

 clasp which, especially if subjected to pressure with a pair 

 of pliers, will effectually prevent the ring from coming off. 

 It may be mentioned that for Moorhens, Divers, and some 

 other water-birds, the rings require to be bent into oval 

 shape to fit the much compressed tarso-metatarsus. 



SER. XI. — VOL. Ill, 2 I 



