SOME QUESTIONS CONCERNING MIGRATION 81 



data led him to the remarkable result that the bird accom- 

 plishes a journey of 1600 miles or so in nine hours, that is, 

 at a rate of 180 geographical miles per hour. But if this 

 speed can be attained by the blue-throat, what may we 

 not believe of really swift birds, such as hobby, swallow, 

 and plover. The Virginian Plover (Charadrius pluvialis) 

 is believed (by those who are satisfied with the assump- 

 tions) to pass in one magnificent flight of fifteen hours 

 from Labrador to North Brazil, about 3200 geographical 

 miles. That would correspond to a velocity of 212 

 geographical miles per hour, and we shall draw the line 

 here. 



Tegetmeier has given facts which show that a carrier 

 pigeon may keep up a rate of 55 miles an hour for several 

 successive hours, and by many observations on herons 

 crossing a narrow strait I convinced myself one holiday that 

 a mile a minute is not an exaggeration. It may be recalled 

 that large birds, such as pheasants, have been known to fly 

 right through plate-glass shop windows, which indicates a 

 high velocity. 



While admitting that facts are few, we venture to adhere 

 to the idea that the migrational flight at its height may 

 well be something far above the ordinary performance. 

 For in migration the bird is often at high tension ; as we 

 have already noticed, low-fliers sometimes fly high, diurnal 

 birds may fly by night, easy-going birds may attain to great 

 speed. If we succeed in forcing a corncrake to winged flight 

 in this country, we see a somewhat lumbering performance, 

 which gives little hint of what the bird can do in migration. 



CONTRAST OF SPRING AND AUTUMN FLIGHT 



As we have seen, the Spring flight is in great part 

 northward, the Autumn flight in great part southward ; 

 6 



