NATURE AS AN ORGANISM 



of birds which feed principally or even exclusively on insects captured 

 on the wing. Such birds will sit motionless on an elevated perch, 

 or perhaps a post, from which they can see in all directions; then 

 suddenly they take the air, catch a passing insect, and return to 

 their perch with a graceful curving flight. Among such birds are 

 the "Widows," black birds with white heads, the Pipridae, most 

 of which have in their plumage a good deal of black, which em- 

 phasizes the brilliance of the red, yellow or white head, and above 

 all the Tyrants, relatives of the Bemtevis, the Siriris, and the pretty 

 "Scissors-birds" with the long forked tails. The Tyrants, in their 

 flight and behaviour, are very Uke the Bee-eaters of Asia and 

 Africa, though the blue-green and yellow plumage of the latter is 

 more brilliantly coloured. They devote themselves more especially 

 to the chase of sting-bearing insects. 



Birds follow the insects into their most secret hiding-places. The 

 tiny beetles which cling to the stamens of flowers and feed on honey 

 are captured by the Humming-birds, whose small size and long 

 bills enable them to draw the insects from their hiding-places, 

 while their extremely adroit flight enables them to hover motionless 

 before a flower. This ability to hover is most necessary, for the 

 flower-stalks, to say nothing of the stamens, are too delicate to bear 

 the weight of the bird, and many flowers are accessible only from 

 the air. I have often been struck by the great numbers of insects 

 living in tropical flowers ; in particular whole flocks of the short- 

 winged beetles may be seen adhering to the stamens. 



Even the beetles and grubs which burrow in wood, and are 

 apparently quite secure from the dangers of the outer world, are 

 dragged out of their dark retreats. How comprehensive is the 

 adaptation of the Woodpecker to its task! The legs are set well 

 back, so that the whole body can follow the stroke of the powerful 

 beak ; and when the dark tunnels are laid open the long, protrusible, 

 and excessively sensitive tongue, with its needle-like point, transfixes 

 the insects, or catches them with its asperities. There are many fine 

 woodpeckers in Brazil, resplendent in black, white and red, or in 

 yellow and green (Plate 28). 



The larvae of gnats and mosquitoes concealed in the ooze of 

 ponds and rivers are eaten by the ducks, whose broad, fringed bills 

 constitute a sieve which lets the ooze escape and retains the larvae. 

 The appetite of these voracious birds is in proportion to the amount 

 of food at their disposal. 



In the tropics the Ant family is most abundantly represented, 



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