CHAP. XX. THROSTLE-BUSHES. 253 



bird-stuffer on Heligoland, told me that birds migrate north- 

 east in spring, and south-west in autumn. Gatke, on the 

 other liand, maintains that the directions are due east and 

 west. Both agree that birds dislike an absolutely favour- 

 able or absolutely contrary wind. The former ruffles their 

 feathers and chills them ; the latter, if too strong, impedes 

 their progress. They prefer a side wind, and probably 

 alter their course slightly to accommodate themselves to 

 it. It is even said that they will sometimes tack. Weather 

 is perhaps as important as wind. Under ordinary circum- 

 stances a bird does not require to rest on Heligoland, and the 

 arrivals for the most part are said not to be from any point 

 of the compass, but perpendicularly from the sky. The 

 islanders describe with great gusto the sudden arrival of 

 thrushes in this manner. There are scarcely any trees on 

 the island, so the peasants make artificial bushes with a net 

 on one side into which the poor thrushes are driven with 

 sticks and lanterns as soon as they alight. Some hundreds 

 are thus frequently caught in one night. By long expe- 

 rience the Heligolanders know when to expect an arrival of 

 birds. Aeuckens related to me how they would watch on 

 favourable nights by the throstle-bushes, when on a sudden, 

 without a moment's warning, a rush and whirl of wings 

 would be heard, and the throstle-bush would swarm with 

 thrushes, not dropped, but apparently shot like an arrow 

 from a bow, perpendicularly down from the invisible heights 

 of mid air. It is supposed that migration takes place for the 

 most part at a high elevation, beyond the range of our 

 vision ; that the birds migrate by sight, and not, as has been 



