118 



rently from utter lack of this impulse to migrate. In the ex- 

 perience of the writer the Mistle Thrush is a bird whose resi- 

 dent numbers fluctuate considerably from this cause; other 

 species are no doubt affected quite as much. The colony of 

 Curlews in West Cumberland, which breed in the fells and 

 winter on the neighbouring coast, which ordinarily enjoys a very 

 mild climate, suffered severely in the arctic winter of 1894 and 

 1895. An examination of dead birds on the beach revealed more 

 of this species than of any other, and it proved to be correspond- 

 ingly scarce in the breeding grounds the following spring. 



Many Redwings winter in England whose migratory instinct 

 seems to be quite evaporated by the time they have arrived here. 

 It is notorious how they suffer during severe weather, though 

 a short further flight would convey them to a place of safety. 

 Mr. Eagle Clarke recounts instances of several other species 

 whose migration instinct, though it carried them to the limits of 

 their customary flight yet failed to land them to a place of safety 

 in the exceptional winters of 1881-2-5-7 (vide Digest). 



In localities, however, where severe winters though not the 

 rule, are by no means infrequent, the migratory instinct may be 

 encountered in still different degree. Herr Gatke in several places 

 alludes to late movements on the part of large numbers of Plovers, 

 Curlews, Sandpipers, Finches and Larks (p. 19). These latter 

 flights may have been termed supplementary migrations. The 

 individuals comprising them appear to hold the intention of 

 wintering in some locality not far from Heligoland, but on 

 the approach of severe weather are forced to make a further 

 move, thus illustrating the fact that though in ordinary winters 

 their migrations would have already come to an end, still, from 

 greater frequency with which severe weather recurs in these 

 localities the migratory instinct to undertake a further move has 

 not been lost but is simply remaining dormant for the time being. 



Other hardy species again will illustrate the winter lives of 

 birds, existing at the time migration had its first inception. Herr 

 Gatke' s graphic description of bird life at Heligoland when the 

 Baltic becomes frozen very far south, and large masses of ice 

 collect about the mouth of the Elbe forms a most striking pic- 

 ture of the latter phase of the phenomena. 



