LONDON BIRDS 43 



superable bar to perching on trees. London naturalists 

 are thus having a pleasant chance offered them of 

 studying evolution in one of its simpler forms the 

 adaptation of life to altered conditions. 



In December 1898 it was the writer's good fortune 

 to witness what must have been a very early experi- 

 ment. Three or four Gulls sat on the top branches of 

 the tallest tree, on the peninsula opposite the India 

 Office, fairly steadily, but every now and then, as a gust 

 of wind swayed their perches, shooting up one wing 

 perpendicularly to right the balance. Ten or a dozen 

 more hovered over them, dropping as far as the tree- 

 top, with both wings lifted till the tips almost touched 

 behind them, and rising again and again to make 

 another attempt as they missed their hold. Twice as 

 many more, perhaps, hung round in a circle, almost 

 motionless, watching the practice with evident in- 

 terest. 



Our great-grandchildren, if all goes well, may number 

 in their lists of British Gulls a new variety Larus 

 ridibundiis, var. Londinensis differentiated from the 

 ' Scoulton Pie ' of our times by a clasping hind toe. 



Herr Heinrich Gatke, in the book in which he has 

 recorded the results of fifty years' experience of birds 

 in Heligoland, has devoted a chapter, which has 

 attracted much attention, to the meteorological con- 

 ditions which influence migration. 



Londoners interested in such matters have lately 

 had opportunities of studying ' the prescience of storms ' 

 displayed by birds, of which Herr Gatke gives proofs, 



