WEST COAST OF SCOTLAND. 93 



season between August 16th and December. I am inclined to 

 look upon these data as indications of the wide-spread waves of 

 the general migration, extending both farther north and farther 

 south. According to the amount of pressure at the starting-points 

 [or possibly the increased area northward occujDied in a parti- 

 cularly fine nesting season, as in 1880] will the wideness of the 

 area be which is passed over by the migratory flocks. I think 

 the rules known to apply in the dispersal and extension of range 

 of species are, in some respects, applicable also to the greater and 

 more extensive waves of migration. 



I could say more regarding the peculiarity of nesting sites 

 being occupied year after year by the same pairs of birds, or of 

 well-known sites being vacated for a few seasons, and again 

 occupied ; or I might dilate upon some curious statistics of the 

 continuous recurrence of foreign species at the same localities, 

 or along the same line of country, but I fear to occupy space with 

 theory only, until we have a larger accumulation of solid 

 material. 



As regards severity of weather apart from winds, unusually 

 early winter was reported from Scandinavia, it having begun 

 there in October (vide ' Field,' Oct. 16th, 1880, p. 590). 



Attention should be drawn also to the admirable work being 

 done on the subject of migration by Mr. J. J. Dalgleish 

 (Bull. Nuttall. Orn. Club), and by Mr. Percy E. Freke 

 (Sc. Proc. Kyi. Dub. Soc, vol. ii., n. s., p. 373, and vol. iii., n. s., 

 separate?). These gentlemen also now propose to colour, or 

 have already finished, maps showing the distribution of the 

 occurrences of American birds in Europe recorded in their 

 papers, which cannot fail to be of much service in oui' work. We 

 would like to see not only American species mapped out in 

 Europe, but rare European occurrences in Great Britain. 



Finally, in endeavouring to arrive at conclusions regarding 

 the causes of migrational phenomena in 1880, we have taken 

 into consideration — 1st. The value of the heights of lanterns 

 above the sea, as against the colour and intensity of lights in 

 1879 ; and we have taken more account of the vertical area of 

 birds' flight in 1880 than in 1879. 2ndly. We have compared 

 the effects of prevailing north-west winds in 1879 pressing 

 laterally upon the lines of migration to those of 1880, which 

 being easterly and north-easterly have had the contrary effect of 



