AUTUMN MIGRATION IN BRITISH AREA 269 



October ; the movement in every direction has a soutJicrn 

 trend. 



A short allusion to Vertical Migration in autumn will 

 bring the present chapter to a close. The descent of 

 mountain species from their upland haunts is just as 

 characteristic of the autumn migration of birds as that 

 migration which takes place in a latitudinal direction. 

 The duration of the period extends over about three 

 months, namely, from August to October, and is there- 

 fore much shorter in duration than the autumn migration 

 of species elsewhere. This is probably due to the more 

 rapid seasonal changes on mountains than on the low- 

 lands, more of that sudden nature which marks the 

 coming on of winter in the Arctic regions. Among the 

 first birds to leave their mountain summer haunts are 

 the Merlin, the Linnet, the Twite, the Lesser Redpole, 

 the Pied Wagtail, the Golden Plover, the Lapwing, the 

 Curlew, and the Dunlin. In all these species, however, 

 the migration is only slight in August, and attains its 

 greatest strength in September, a slight movement 

 extending into October. The later birds to leave are 

 the Stonechat, the Gray Wagtail, the Meadow Pipit, 

 the Wood Lark, and the Sky Lark. With these species 

 the migration is only slight during September, and 

 reaches its maximum in October, one species, the Sky 

 Lark, prolonging its flight into November. In our 

 latitudes vertical migration is practically over by the 

 end of October, but in more northern areas it has ceased 

 for the year months earlier. 



The following table will indicate the duration of the 

 principal Migration across the British Archipelago in 

 Autumn. 



