Wings 329 



and bushes; while goldfinches and woodpeckers swing 

 past in long undulations, a loop and a catch, a loop and 

 a catch, — with wings wide extended, then quickly closed. 

 Hummingbirds have a remarkably insect-like flight; the 

 rapid reflex whirr of the wings holding them perfectly 

 still, poised m mid-air. 



When ornithologists think that they have formed a 

 correct theory of flight and that, given such and such 

 conditions, certain results must follow, such a bird as the 

 Crested Screamer soars into their mental atmosphere and 

 upsets every calculation. Such a bulky and short-winged 

 bird, by all good "rules" of flight, should confine itself 

 to short laboured efforts, barely skimming the low bushes 

 of its South American haunts! But it refuses to be thus 

 limited. Of this species it is said : " The Screamer is a very 

 heavy bird, and rises from the ground laboriously, the 

 wings, as in the case of the swan, making a loud noise. 

 Nevertheless it loves soaring, and will rise in an immense 

 spiral until it wholly disappears from sight in the zenith, 

 even in the brightest weather; and considering its great 

 bulk and dark colour, the height it ultimately attains 

 must be very great. On sunny windless days, especially 

 in winter and spring, they often spend hours at a time 

 in these sublime aerial exercises, slowly floating round 

 and round in vast circles, and singing at intervals. How 

 so heavy and comparativel}' short-winged a bird can sus- 

 tain itself for such long periods in the thin upper air to 

 which it rises has not yet been explained." 



I find in my journal the following account of a flight 

 of vultures which we saw in a desolate alkali desert in 



