BIRD-NESTING IN ARGENTINA 377 



premium. The old, disused nests of brush-birds (Synal- 

 laxis), or lenaieroSj were inhabited by mocking-birds which 

 built a nest of their own within the huge structure of twigs; 

 and, when the mocking-birds were away, cowbirds slipped 

 in and deposited a few eggs. One mocking-bird had been 

 so unwise as to place its nest in a thorny bush covered 

 with dense foliage so that it could not be watched from a 

 distance and defended from cowbirds; before the owners 

 were ready to use their new home, it had received many 

 visits from the black parasites (M . b. bonariensis) who left 

 their cards in the shape of fourteen speckled eggs. We 

 collected this "set" but have the idea that this only en- 

 couraged the cowbirds to increased efforts. 



The abundance of ducks in South America in places where 

 one least expects to find them, is a source of never-ending 

 surprise. A small stream flows through the valley at Til- 

 cara. It is nowhere more than twenty feet across, and two 

 or three feet deep, but flocks of green-winged teals visited 

 it regularly at dawn and dusk. They swam in the rapid 

 water, and then lined up on the rocky bank for a quiet nap. 



The inhabitants of Tilcara shot many, but others came 

 to the same place daily. 



Of mammals there were but few. Cavies, as usual, lived 

 among the rock piles and in the stone fences, and a few other 

 small rodents inhabited the grain-fields. One day we secured 

 a fine specimen of the rare, elusive yellow cat called gato 

 pamperOj or pampas-cat. It was stealing cautiously along 

 the river-bank; but I am unable to say whether it had come 

 in quest of fish or merely for the purpose of quenching its 

 thirst. Our work in this region being completed, we re- 

 turned to Perico, and prepared for the journey to Em- 

 barcacion. 



