52G Dr. A. L. Thomson : Results oj a Stmhj of [Ibis, 



parliculur areu is accordinoly significant only when it can be 

 shown that the s[)ecics tends to yield a good proportion of" 

 records under circumstances such as are prevalent there. 



It is therefore thought probable that promiscuous marking 

 has now had a sufficient trial in the British Isles and that it 

 will be found, more especially when summarised results of 

 the " British Birds " scheme have also been published, that 

 the necessary data are now available for the formulation of 

 more definite plans of campaign for concentrated action. 

 If possible, definite problems should be kept in view and 

 the v.'ork of marking should be systematically directed to 

 th(^ accumulation of relevant facts. The Lapwing, to give a 

 single instance, would assuredly yield results of the 

 highest theoretical interest if it could be marked simul- 

 taneously and in a large number of selected districts — say, 

 the north of Scotland, the south of England, Ireland, 

 Holland; a district of France, and a district of Norway. 



XIII.— REFERENCES. 



{^References not relating to the marking method are given 

 in the text.) 



(1) Baldwin, S. Prentiss (1919).—" Bird-Banding by Means of Syste- 



matic Trapping." {Ahs. Proc. Linn. Soc. Keiv York, xxv., 

 2.3.) 



(2) Baetsch, Paul (1904).—" Notes on the Herons of the District of 



Columbia." {Smiths. Miscel. Coll., x\\., 104.) 



(3) Cole, Leon J. (1902).— " Suggestions for a Method of Studying 



the Migrations of Birds." {Third Report of the Michigan 

 Academy of >St:ience, 67.) 



(4) (1909).— "The Tagging of Wild Birds as a Means of 



Studying their Movements." {Auk, xxvi., 137.) 



(5) (1910).—" The Tagging of Wild Birds : Report of Progress 



in 1909." {Avk, xxvii., 154.) 



(6) Douglas, S. R. (1917). — "An Experimental Investigation of the 



Migration of Woodcock breeding in the West of Ireland." 

 yRj-oc. Zool. Soc. London, 1917, 159.) 



(7) Hamilton, John {1908).— {Field, 1908, 717 & 745.) 



(8) Herman, Otto, and Schenk, Jakob (1909 et seq.).—{Aquila, 1909, 



34) : and subsequent periodical reports. 



