The Delta of the Parana 173 



their mode of proceeding is so regular that the flock well 

 deserves the appellation of an army. They sweep down 

 with a swift graceful flight and settle on the ground with 

 loud joyful cries, but do not abandon the order of attack 

 when the work of devouring has begun. The flock often 

 presents a front of over a thousand feet, with a depth of 

 sixty or seventy feet ; all along this line of battle the excited 

 cries of the birds produce a loud continuous noise ; all the 

 birds are incessantly on the move, some skimming along 

 the surface with expanded wings, others pursuing the 

 fugitives through the air, while all the time the hindmost 

 birds are flying over the flock to alight in the front ranks, 

 so that the whole body is steadily advancing, devouring the 

 grasshoppers as it proceeds. When they first arrive they 

 seem ravenously hungry, and after gorging themselves they 

 fly to the water, where after drinking they cast up their 

 food, and then go back to renew the battle. 



I saw a number of the Yellow-shouldered Marsh- 

 birds (AgelcEus thilius), resembling our Red- winged 

 Blackbirds, from which they differ apparently in being 

 a little smaller, and having the shoulders of the male 

 bright yellow, instead of red as in the case of our 

 species. The female is somber in plumage and lacks 

 the gay epaulets of her mate. There were many of 

 these birds among the rushes as we entered the canal 

 after we had crossed the river. Here I also caught 

 sight of the Scarlet-headed Marsh-bird (A mblyrhamphiis 

 holosericeus) . They were conspicuous objects as they 

 clung to the tops of the tall rushes. I was happy to 

 see the Cardinal Finch (Paroaria cucullata) alighting 

 in a thicket. Its crested head recalls our own Virginian 

 Cardinal, but the markings are different, the lower 

 parts of the body being white, the back and wings gray, 

 while the crested head and throat are brilliant scarlet. 



