ON THE MIGRATION OF BIRDS. 911 
do not quite see why the bird, once in full migratory swing, should 
stop again till in the natural course of events it flies itself to death. 
Compared with the drifting seed, it is positively at a disadvantage, 
having no sea coast to bring it up: like that marvellous mechanical 
leg we read of somewhere, which when once wound up and started 
could not be stopped again, so the bird ought to keep going—aim- 
lessly and purposely, perhaps—but still going. 
It is a well-ascertained fact that the young of the year of many 
birds migrate before their parents, and in separate flocks; these 
have never travelled the route before, and how they find their way 
over these thousands of miles of sea and land seems a very 
puzzling problem. It is a curious fact that although the young 
come in separate flocks, we constantly find an old bird or two— 
usually old females—amongst them, so that the young may to 
some extent be in leading strings. As most birds, however, travel 
by night, and on very dark ones too, they cannot trust to guidance 
alone, and they are not able to make use of such landmarks as 
prominent capes and headlands. They come much as did the old 
sea rovers,—without chart or compass, “by rule of thumb,’— 
certain to hit the land somewhere, and when once the land is 
seen knowing all will be right. With the wonderful vision birds 
possess, and the great height at which they usually travel, they 
would be able, much more readily than we suppose, at early dawn 
to distinguish known features of land or sea coast (supposing 
them to have travelled the route before) at, to us, immense 
distances. Nor would their inherited instinct, I believe, fail under 
any circumstances, whether in young or old, to bring them to 
their goal. 
As a familiar instance of this inherited instinct in birds we may 
cite the case of the Common Partridge. How is it, except by this, 
that Partridges, having had no actual experience for many genera- 
tions of the real Kite or Buzzard, cower or rush at once to the 
nearest shelter when the paper kite’s “shadow saileth across the 
open shaw”? Some years since, when the telegraph-wires were first 
carried across the Lincolnshire marshes, Partridges and Plover were 
constantly picked up killed by flying against the wires; now, after 
the lapse of some years, this is rarely if ever the case, the genera- 
tions of Partridges that witnessed this immolation of their comrades 
has long passed away, yet the present birds have learnt through 
this same hereditary instinct to avoid the danger. 
