BRITISH BIRDS OF FASTEST FLIGHT 27 
from 1000 feet at between 150 and 200 miles per 
hour at a partridge, and has later seen the same 
peregrine chase the same partridge from a standing 
start, he will appreciate the importance of con- 
sidering only level flight. In the first instance 
the hawk is nearly 100 miles per hour faster than 
the quarry, in the second, he can only just overtake 
it at all. There is no conceivable way of measuring 
the speed of these downward flights accurately, 
but no one who has done any hawking will deny 
that 120 miles per hour is within the power of a 
great many species. When we come to consider 
level flight, there is a very difl*erent story." 
3. There must be some evidence to show whether 
the bird is flying at its maximum speed or not. 
As was recently pointed out in an interesting 
article^ by Colonel R. Meinertzhagen, D.S.O. : 
" Birds have two speeds : a normal rate, which is 
used for everyday purposes and also for migi-ation, 
and an accelerated speed, which is used for pro- 
tection, or pursuit, and which in some cases nearly 
doubles the rate of their normal speed ; some of 
the heavier birds can probably only accelerate to 
a slight extent. In this conclusion I am naturally 
^ " Velocity of Flight among Birds," by Colonel R. Meinertzhagen, 
D.S.O., in the Ibis for April 1921, pp. 237-238, 
