28 THE GAME BIRDS AND WILD FOWL 



normal north-easterly route. Four years later (in 1863) a much more important 

 irruption took place, this time consisting probably of thousands of individuals, 

 and very much the same route was followed; although, as might be expected in 

 such a great rush of birds, the wave spread wider and further, extending to Italy 

 and the Pyrenees in the south, to Scandinavia and Archangel in the north, and 

 throughout the British Islands to the Faroes. Many birds endeavoured to breed 

 in places that were best adapted to their requirements. In 1888 another and even 

 more important wave of Sand-Grouse spread westward over Europe, the par- 

 ticulars of which will be still fresh in the mind of the reader. This invasion was 

 undoubtedly the most successful of all; and so well did the birds appear to be 

 established, that in our islands a special Act of Parliament was passed (in 1888, 

 but not becoming law until early in the following year) for their protection. 

 Gatke has recorded a vast irruptic wave of Jays (Garrulus glandarius) that 

 swept over and past Heligoland during three successive days in October, 1882. 

 This irruption was estimated to number millions, and curiously enough since that 

 year down to the present one solitary Jay only has been seen at the island. As 

 the Jay does not range further east than the Urals and the Volga, where all these 

 birds came from is a question which appears to defy solution. Gatke also records 

 a similar irruptic wave of Mealy liedpoles (Linota linaria), which, during the 

 4th and 5th of November, 1847, had attained such proportions "that the whole 

 island was literally covered with them." Similar irruptic waves of Goldcrests 

 (Eegulus cristatus) are occasionally remarked. Now nothing can more clearly 

 indicate the abnormal character of these irruptic movements than the fact that 

 they are utterly abortive, either as a means of preserving the individuals under- 

 taking them (for in no case is a corresponding permanent increase of the species 

 remarked in the areas invaded) or as a means of colonising new districts with the 

 surplus population from old ones. To class them either with normal migration 

 or with range expansion is therefore erroneous. We must bear in mind the 

 fact that these waves of avine life are drifting into districts already tenanted with 

 a bird population as large as conditions of life will allow, or into areas where the 

 conditions of existence are quite different from those they have proceeded from. 

 It is a sadly significant fact that these vast bird waves never show any sign of 

 a return ebb. Like leaves scattered by the autumn wind, the birds composing 

 them perish, for Nature's edicts are inexorable : her delicate balance cannot be 

 disregarded with impunity. 



This Sand-Grouse appears to be more or less a migratory species, a nomadic 

 migrant, but one whose wanderings normally take place within the usual area of 

 dispersal. They are apparently early birds of passage, for Eadde states that they 

 arrived at their breeding grounds before the end of March, during very cold 

 weather, the thermometer falling nearly thirty degrees below zero at night. A 

 month later they were nesting. All through the year this bird appears to be more 

 or less gregarious, and to breed in colonies which are scattered here and there 



