BEITISH BIEDS. 85 



are caught (as here) in clap-nets. " It is not unusual to see a man with 

 bunches of several hundreds, which are sold at a ridiculously low price." 



4. Where do they migrate to ? 

 Of course some return to the north, as Redwings and other winter 

 visitants ; some go south. Livingstone says, in his last Journals, vol. i, p. 336 : 

 — " Swifts, Senegal Swallows, and the common Dark-bellied Swallows appeared 

 at Kizinga in the beginning of October 1868." This place is situated on 

 Lake Moero, 3000 feet above the sea, just to the west of Lake Tanganyika, 

 and far below the equator ; but Hirundo rustica, our common Swallow, is 

 stated to reach the Cape. 



5. Why do they return ? 



Their return is perhaps hardly less marvellous than their departure, 

 being contrary to the principle in Nature of least action. The love of home 

 (a feeling common to birds, beasts, and fishes — may I not say, to all 

 creatures ?^ probably operates in a great degree. Cosmos is constituted on a 

 nice balance of forces. If migratory impulse and other causes draw a bird 

 away, one of the greatest attractions takes him back : this is the law of 

 natural location — one which causes every creature to wish to remain round 

 a certain spot. Without it the earth would be nothing but confusion, like 

 the meeting in a road of several flocks of sheep belonging to various owners. 

 The most deadly fights would ensue ; for every animal, man included, would 

 do battle for the best situation. By means of this law each thinks his own 

 the pleasantest ; and it has had more influence on species than " natural 

 selection," because it keeps the breeds and races from mixture. In short, 

 it preserves order ; without it all would be chaos. 



Buckland says (' Curiosities of Natural History,' vol. ii. p. 285) : — 

 " Strange things are heard at midnight by fishermen from Dover drifting 

 along far out at sea. All of a sudden a curious rushing and rustling sound 

 comes over the boat, accompanied by low musical twittings ; it passes 



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