404 KEPORT — 1900. 



siderable number of rare and critical species made by ornithologists — data, 

 in fact, that it was impossible to obtain from the light-keepers, whose 

 knowledge of birds is, naturally, limited. 



Since the year 1891 Mr. Harvie-Brown and myself, with the valued 

 assistance of Mr. Lionel W. Hinxman and Mr. T. G. Laidlaw, have 

 prosecuted an inquiry into the movements of birds in Scotland, and the 

 investigations are still proceeding.^ In addition to the observers at the 

 liwht-stations, we have enlisted the services of a number of ornithologists. 

 This again has resulted in the acquisition of much useful supplemen- 

 tary information. 



Now that the data have been made as complete as possible, the time 

 has arrived when, for the first time in the annals of British Ornithology, 

 it is possible to write an authoritative history of the migrations of each 

 British bird, for few indeed among our native species are entirely 

 sedentary. 



This is the task I now propose, with the approval of the Committee 

 and of the British Association, to undertake. 



I submit herewith a Summary of Details of the various migratory 

 movements of two species — (I.) the Song-Thrush (Turdus musicus) and 

 (II.) the White Wagtail {Motacilla alba) — as examples of my method of 

 treatment. 



Sum/mary of Details. 

 I. Song-Thriish (Turdus musicus). 



Introductory. — The Song-Thrush furnishes us with a most excellent 

 example of the complex nature of the phenomena of bird migration as 

 observed in Great Britain and Ireland. 



The various movements of this species cover a period of nearly ten 

 months of the year, June indeed being the only month in which the Thrush 

 does not figure as a migrant in the records amassed by the Committee. 



During this period it plays a varied role as a migratoiy bird, being a 

 summer visitant, a bii'd of passage in spring and autumn, a winter 

 visitant, a winter emigrant, and lastly, it is chiefiy to be regarded as a 

 rare casual visitor to the most northerly of the British Isles, namely, the 

 Shetlands. 



In addition, the Thrush is a permanent resident in certain districts, 

 more especially in the gardens and immediate neighbourhood of cities and 

 towns, where even in Scotland a number remain througliout the year. 

 Such residents, however, probably form the minority of our British 

 Thrushes. 



AuUhmn Emigration of Suinmer Visitors. — At the end of summer- and 

 in the early autumn a considerable number of the Thrushes which have 

 reared their broods with us, especially those which inhabit the elevated 

 districts, emigrate towards the south.^ 



' The Keports appeared in the Annals of Scottish Natural History for 1893, 

 pp 147-164; 1894, pp. 146-153; 1895, pp. 207-220; 1896, pp. 137-148; 1897, 

 pp. 137-151 ; 1898, pp. 200-217; 1899, pp. 140-158; 1900, pp. 70-87. 



- On July 8, 1882, five Thrushes struck the lantern at Slyne Head Lighthouse 

 (west coast of Ireland), one of which was killed. In 1885, on July 3 and 11, several 

 Thrushes are recorded at the Inner Fame. On all these occasions the weather was 

 very unsettled, and thunder prevailed. 



3 Mr. T. G. Laidlaw, whose home in Peeblesshire lies 900 feet above the sea, 

 informs me that the Thrushes leave that district ' to a bird ' in the autumn, and 

 return during the early months of the year. 



