The Woodhewer Family. 255 



ing in tlieii' bands scores of widely different species, 

 and in size ranging from tbose no larger than a 

 wren to others as big as a magpie. It is certainly 

 very advantageous to them. As Belt remarks, they 

 play into each other's hands; for while the larger 

 creepers explore the trunks of big trees, others run 

 over the branches and cling to the lesser twigs, so 

 that every tree in their route, from its roots to the 

 topmost foliage, is thoroughly examined, and every 

 spider and caterpillar taken, while the winged 

 insects, driven from their lurking-places, are seized 

 where they settle, or caught flying by the tyrant 

 birds. 



I have observed the wandering bands only in 

 Patagonia, where they are on a very small scale 

 compared with those of the tropical forests. In the 

 Patagonia thickets the small tit-like creeper, Laptas- 

 thenura, is the prime mover ; and after a consider- 

 able number of these have gathered, creepers of 

 other species and genera unite with them, and 

 finally the band, as it moves through the thickets, 

 draws to itself other kinds — flycatchers, finches, 

 &c. — many of the birds running or hopping on the 

 ground to search for insects in the loose soil or 

 under dead leaves, while others explore the thorny 

 bushes. My observations of these small bands lead 

 me to believe that everywhere in South America 

 the Dendrocolaptidai are the first in combining to 

 act in concert, and that the birds of other families 

 follow their march and associate with them, know- 

 ing from experience that a rich harvest may be 

 thus reaped. In the same way birds of various 

 kinds follow the movements of a column of hunting 



