A Trip to Mar del Plata 193 



to the passing train, but two, which were quite near the 

 track, just as we came alongside gave a couple of quick 

 jumps, flapped their wings, and then rose and majesti- 

 cally soared away. I was much interested to see at one 

 place a company of a dozen or more white-faced ibises 

 (Plegadis guarauna) wading about among the aquatic 

 grasses at the edge of a lagoon. This bird is said to be 

 quite abundant upon the pampas. Those I saw seemed 

 to be intent upon feeding, and were stalking about, their 

 heads down, probing with their long beaks in the mud. 

 Hudson says of them: 



Their flight is singularly graceful ; and during migration the 

 flocks are seen to follow each other in rapid succession, 

 each flock being usually composed of from fifty to a hundred 

 individuals, sometimes of a much larger number. It is 

 most interesting to watch them at such times, now soaring 

 high in the air, displaying the deep chestnut hue of their 

 breasts, then descending with a graceful curve toward the 

 earth as if to exhibit the dark metallic green and purple 

 reflexions of their upper plumage. The flock is meanwhile 

 continually changing its form or disposition, as if at the 

 signal of a leader. One moment it spreads out in a long 

 straight line; suddenly the birds scatter in disorder, or 

 throw themselves together like a cloud of starlings; as 

 ruddenly they again reform to continue their journey in the 

 figure of a phalanx, half- moon, or triangle. The fanciful 

 notion can scarcely fail to suggest itself to the spectator 

 that these birds go through these unnecessary evolutions 

 intelligently in order to gain a greater proficiency in them 

 by practice, or, perhaps, merely to make a display of their 

 aerial accomplishments. The glossy ibis has another 

 remarkable habit when on the wing. At times the flock 

 appears as if suddenly seized with frenzy of panic, every 

 bird rushing wildly away from its fellows, and descending 



with a violent zigzag flight; in a few moments the mad fit 

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