Another Mystery. 71 



to provide for a brood also. The young of the cuckoo 

 are so voracious that it has been observed to be hard 

 work for a pair of foster-birds to satisfy the ravenous 

 maw of one. Indeed it has been set down as an 

 estabhshed fact that the young cuckoos struggle to 

 eject each other from the nest if put together, and the 

 stronger survives, but this is not yet sufficiently or 

 finally proved. Though there has been much exag- 

 geration about time between layings, the cuckoo, as 

 we have decidedly seen, does not deposit her eggs 

 quite so rapidly as some other birds. Whether this 

 slower deposition of eggs has been encouraged by 

 later habits, or was original to the bird, may well be 

 an open question ; but in the former case you would 

 have a very marked departure from general habit ; in 

 the latter you have the survival of a species in face of 

 such drawbacks in its own habits and tendencies as 

 is at least exceptional almost beyond belief. 



The whole question of the migration of the young 

 cuckoos later than the parents is one which also in- 

 volves something like mystery. Kad they from 

 hatching lived along with their true parents, there 

 would not have been so much to wonder at in their 

 following them ; but having been so far reared apart, 

 and having so far lived apart, their migration forms, 

 perhaps, one of the strongest illustrations of the 

 power of inherited instinct that we have. 



Inherited instinct ! Yes : if it were not that there 

 is so much to suggest that the cuckoos were originally 

 quite like other birds in all the points in which they 

 now so much differ from them. In truth, nothing is 

 more misleading than this word instinct. 



Unlike most other birds, the female cuckoos are, as 



