22 INTRODUCTION. 



it towards the Continent at the very same time. These common 

 British birds are regarded as resident all the year round ; but 

 tli is is only true of the species — not of the individual. The 

 blackbird, for instance, is one of our habitual residents, but is so 

 because of the Continental ones that come in winter to fill the 

 places of our native-born emigrant birds. In September the 

 young leave us, and their place is taken by other young birds 

 coming in October and November from districts east or south- 

 east of Britain. Should our winter be severe, our old birds 

 will also leave, and in their place we have an influx of old 

 blackbirds from the Continent pushed forward by similar causes. 

 In spring the Continental visitors leave, and our so-called 

 resident blackbirds come back to their nesting quarters, which 

 keeps up the supply independent of local influence. On the 

 11th, 12th, and 13th of November 1884 there was an almost 

 continuous rush of them, night and day, noted at the East 

 Coast stations. Severe weather on the Continent was probably 

 the cause of this unusual migration, which was greatly in excess 

 of any previous reports. The area of bird life in winter is 

 greatly restricted by the covering of immense regions in the 

 north with ice and snow, thus necessitating their entire abandon- 

 ment for months by birds. The pressure thus caused in more 

 temperate regions is relieved by the wise arrangement whereby 

 the less northerly make way for the more northerly by moving 

 for a time further south. The last fortnight in October is the 

 usual period of the " great rush " of immigration. Heligoland 

 was one of the Committee's outlying stations, and was of utmost 

 importance, being situated on the main highway of migration to 

 Britain. From June 28th to the end of the year Mr Gatte 

 observed no fewer than 118 different species of migrants on that 

 island. Some of these passed over in prodigious numbers, 

 especially redstarts, whinchats, and starlings. " In duration and 

 number the migration of starlings exceeds that of any other 

 species." They passed from the 14th to 25th of October in 

 immense clouds. 



The Scottish returns were arranged by Mr Harvie Brown, who 

 makes migration a special study ; and the Scottish ornithologist 

 will find his report full of interesting notes. He tells of a 

 swallow taken at the Bell Kock lighthouse as early as March 

 13th ; it was so exhausted that on admittance to the lighthouse 

 it lay down and slept for sixteen hours. He says the Isle of 

 May has proved one of the best stations in Scotland for migration 

 observations. On the night of the 4th of October 1884 — at the 



