ao6 BIRDS OF LA PLATA 



very abundant in the rush-beds in the Rio Negro 

 valley, and Durnford met with it much further 

 south on the river Sanguelen, a tributary of the 

 Chupat* Migratory birds are, as a rule, very little 

 given to wandering ; that is to say, they do not go 

 much beyond the limits of the little coppice, reed- 

 bed, or spot of ground which they make their summer 

 home, and this species is no exception* It spends the 

 warm season secluded in its rush-bed : and when 

 disturbed flies with great reluctance, fluttering feebly 

 away to a distance of a few yards, and then dropping 

 into the rushes again, apparently quite incapable of 

 a sustained flight* How a bird so feeble on the wing, 

 and retiring in its habits, is able to perform a long 

 annual migration, when in traversing vast tracts of 

 open country it must be in great peril from rapacious 

 kinds, is a great mystery* No doubt many perish 

 while travelling ; but there is this circumstance in 

 their favour : an incredible number of birds of 

 various kinds, many as weak and exposed to attack 

 as the PhlceocrypteSt migrate simultaneously ; Hawks 

 are but thinly scattered along their route, and as a 

 rule these birds feed only once or twice a day, if the 

 meals are large enough to fill the stomach, so that 

 while the Hawk is inactive, digesting his meal, 

 thousands of migrants have sped by on their journey 

 and are beyond his reach for ever. 



The Spine-tail seldom ventures out of its rush- 

 bed, but is occasionally seen feeding in the grass and 

 herbage a few yards removed from the water* Its 

 language is peculiar, this being a long cicada-like 



