PLATE VI. 



Chart of North-Western Europe showing Typical Weather 

 Conditions, with North-Westerly Winds, over the British 

 Isles 



A depression lies to the eastward of and extends to our Isles ; while 

 pressure is highest to the north-west and south-west. Wind, circulating 

 cyclonically round the pressure minimum, being north-westerly and 

 northerly over the British area and the North Sea region generally. 



This type of weather is the most unfavourable of all for bird-movements 

 between the British Isles and the Continent. During its prevalence the area 

 from which we derive the great majority of the migrants in the autumn, 

 and often our own shores from which they return in spring, are under 

 unsettled weather-conditions, and hence adverse for these movements. 



On the other hand, the conditions prevailing over Iceland and the 

 countries to the south-west of us are not unfavourable for migration from 

 those areas to the British Isles. (See also p. 177.) 



