138 BIRD BEHAVIOUR 



have, it having become unimportant. The sandy 

 young of the Partridge and Gull above mentioned 

 might be cited as important confirmatory evidence, 

 their exceptional plain colouring being in this case 

 just what was wanted for protection. 



It is also well known that the chicks of most 

 ground-birds instinctively crouch when alarmed, 

 after the fashion of most assimilatively coloured 

 creatures. But on the other hand there are several 

 cases in which birds of similar habitats have widely 

 different down-coloration, and the reverse ; some 

 have been mentioned in the case of the Geese, 

 and among the Ducks we find that the young of 

 the Tufted Duck and Pochard, very similar in 

 habits and diving power, and breeding on the same 

 waters, are very different in the down, the young 

 Pochards being patterned, vejy like the young of 

 the surface-feeding Mallard, and the young Tufted 

 nearly all black. Conversely, the ducklings of 

 Mallard and Muscovy Ducks are both patterned in 

 black and yellow, and yet the former never breeds 

 in the tropics in a wild state and the latter is 

 essentially a bird of the hot zone of America, so 

 that their environments must differ much more 

 than those of the Pochard and Tufted Duck. 



Emus are more strongly striped in the down than 

 any other young birds except Grebes, and one could 

 hardly have birds more widely separated in habits, 

 Emus being almost the biggest of land runners, and 

 Grebes the most aquatic of all birds, and of 

 moderate or even small size. 



