302 



BIRDS. 



decided extension of range to southward has been caused by any 

 slight change of temperature over such a small area as Scotland, or 

 by the difference of the temperatures upon the north side of the 

 Grampians, and upon the south sides of the same range; but the 

 facts stand for themselves that from the 3rd May 1903 a continuous 

 BLIZZARD blew without the change of a single point of the compass from 

 the direct north-east^ during all the time between May 1st and May 17 th; 

 and, as I have related before, Snipe and Woodcock were alfected in 

 unmistakable manner (read back under species in my last volume) ; 

 aiid on the 7iight of the 3rd May and Uh May 1903 there were 

 seventeen degrees of frost recorded even as far south as Central Scotland, 

 and I am certain that this was a very general state of affairs during 

 that very phenomenal spring and summer. I would ask those really 

 interested in such matters to read back. I am quite willing to admit 

 that the increase and extension southward may simply have been 

 due to natural increase and congestion at old centres ; but I see no 

 harm in putting forward the facts connected with an abnormal 

 summer such as that of 1902 undoubtedly was, as also the following 

 summers of 1903 and 1904, and asking other naturalists resident in 

 Scotland at that time to compare along with their own experiences. 

 I have found Dotterels at their nesting grounds in Eussia not more 

 than 60 or 100 feet above sea-level. But what a Dotterel may 

 be able to endure which represents the older acclimatising race, or 

 may be looked upon as one of the " fittest " survivals as compared 

 with ours in Scotland, I am unable to gauge. But one thing at least 

 suggests itself to my mind, and that is : If a blizzard lasted seven- 

 teen days from the north-east over Scotland — as it did — and con- 

 tinued cold and inclement all summer, and the whole summers of 1902, 

 1903, and 1904 partook of Arctic severity — as they did — and in the 

 very slightest degree affected the several birds' choice of southerly 

 aspects — how much more would the birds in more northern countries, 

 nesting at much lower altitudes above sea-level, be affected by 

 blizzards there of such duration as seventeen days. Daily I have 

 seen "the drift north to-day and south to-morrow" of hundreds of 

 migrants at the opening of summer in Russia, and this " swinging 

 back and fore of the pendulum," so to express it, was most clearly 

 and distinctly dependent upon the changes of weather, and of the 

 temperatures which constantly took place at that season in northern 

 Russia. Those who have never seen — witnessed for themselves — this 

 distinct phenomenon at a settled fixed point of observation, such as 

 Ust Zylma was to Seebohm and myself in 1875, can scarcely realise 

 its rhythmic pulsing recurrence — to-day, to-morrow, and for days together. 



