SIDE LIGHTS ON BIRDS 



velocity of the wind at the altitude of flight. He 

 found that testing the speed of birds was ex- 

 cellent practice for the men and assures us that 

 the results may be taken as accurate for all 

 practical purposes. He discounts at once Gatke's 

 assertion that birds attain a largely increased 

 velocity by travelling in the more elevated layers 

 of the atmosphere. He shows that greater 

 height tends to lesser speed as the atmosphere 

 is rarer and therefore offers a less suitable mixture 

 on which wings can beat. Birds at a great 

 height, he observes, experience the same diffi- 

 culty as a man trying to swim in froth. 



The following summary, giving the miles per 

 hour travelled by certain birds observed, will 

 make the main facts plain. 



Corvidae 31 — 45 



Smaller Passeres 20 — 37 



Geese 42 — 55 



Tame Pigeons 3° — 36 



Starlings 38 — 49 



Falcons 4° — 4^ 



Ducks 44 — 59 



Sand-grouse 43 — 47 



Waders 34 — 5i 



but mostly from 40 — 51 



The figures, which may be termed official, give 

 the swift 68 miles per hour and the swallow, 

 rather curiously only 34 — 37I. The writer asserts 

 that swallows are most deceptive as regards 

 their flight. They are, he says, neither strong 

 nor rapid flyers, and he refuses to place any 

 reliance on the data of the Roubaix swallow 

 which the " Zoologist" recorded as having been 

 released in Paris, and as returning to Roubaix, 

 a distance of 160 miles in 90 minutes, giving a 

 rate of 106 miles per hour. Still, we take it, 

 that although leisurely on migration, the swallow 

 is capable of very much greater speed than the 



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