18 SYLVAN SECEETS. 



desire for the far northern water-brinks, 

 along with an elusive and tantalizing recol- 

 lection of a time, thousands of years ago, 

 when he, in the body of a remote forebear, or 

 clamorous male ancestor, voyaged the high 

 thin air in one of those triangular flocks 

 sketched on the violet sky of spring, or on 

 the gray-blue heaven of autumn. 



I have seen a flock of domestic geese, in 

 early spring or late autumn, rise suddenly 

 and fly around in the air, uttering wild 

 cries and exhibiting every sign of ecstatic im- 

 pulse, for wliich there appeared no suflicient 

 cause in their surroundings or condition. I 

 have not a doubt that this is an almost in- 

 voluntary movement toward migration gen- 

 erated by a feeble return of the old hereditary 

 natural desire. 



The foregoing facts and instances, to which 

 might be added many more of a like charac- 

 ter, all tend to prove that birds possess some- 

 thing like hereditary memory. On the other 

 hand a few facts may be cited tending to es- 

 tablish the proposition that wild birds are 

 modifying themselves in response to the exi- 

 gencies arising out of recent changes in their 

 surroundings. 



The red-headed woodpecker is rapidly be- 

 coming an expert fly-catcher, a pursuit for 

 which his physique does not especially fit 

 him, and he is already a grain and fruit-eat- 

 ing bird, although his bill and tongue are 

 made for extracting insects from rotten wood. 



Chimney swallows have almost quite aban- 

 doned hollow trees for their nesting-places, 

 even in our most thickly wooded areas, pre- 

 ferring our chimneys. 



The high-hole, or flicker, has become almost 

 entirely a ground bird in its feeding habit, 



