BRITISH BIRDS OF FASTEST FLIGHT 57 
indica or brown-necked spine-tailed swift, which 
is a larger species (length about 9 inches, tail 2-6 
— wing 8 — tarsus 6-8), as being " equal or possibly- 
even superior in speed to ChaeUira nudipes — 
so wonderful is their flight that Mr. H. R. P. 
Carter remarked that a flock of Alpine swifts, 
passing over immediately after some of the 
present species, ' seemed to fly like owls after 
the arrow-like speed of the spine- tails.' " 
I think, therefore, that if the speed in horizontal 
flight is alone to be considered, the spine-tailed 
swift is the fastest bird which flies in the British 
Isles, that the Alpine swift comes next ; then come 
the northern falcons (or as they are usually 
called, gyr- falcons) and the peregrine falcon, in 
the order named, except in the case of a very 
short flight, in which case the Golden Plover and 
teal, being faster off the mark and better sprinters, 
will fly more quickly than the falcons, though 
they will, when the latter really get going, be 
gradually overtaken. 
There remains for consideration the speed of 
the golden eagle and falcon in their downward 
flight, when stooping at their prey. There is no 
certain method of comparing their respective 
speeds in this unique kind of flight either with 
