I 



^°*' ioiG^"^] HussEY, Spring Birds of La Plata. 393 



sallies for passing insects in true flycatcher fashion, often coming quite 

 close to me. And I have seen them pursuing each other about, when they 

 passed within a few feet of me, heedless of my presence. 



40. Sisopygis icterophrys (Vieill.). — I first saw this pretty tyrant 

 bird in the observatory grounds, on August 21; for about a month I did 

 not see it again, then it became quite common where the open country was 

 broken by a few trees or bushes. It is a quiet bird, with many of the habits 

 of the true flycatchers. 



41. Lichenops perspicillatus Gm. "Pico de plata " (Silver- 

 bill). — This remarkable tyrant bird is common in marshy regions; it is 

 unique in many ways. The sexes differ not only in color, but structurally 

 and in habits. Both feed on the ground, but the male also gets a part of 

 his food on the wing. All the males seem to possess the habit of shooting 

 up vertically to a considerable height, then dropping back suddenly to 

 their perches; but the performance differs somewhat in different lairds. 

 One bird may turn a somersault at the height of his climb, while another 

 may drop back to within a few feet of the perch before executing a lightning- 

 like flip, and I saw one or two birds which did not turn over at all, though 

 I watched them closely for some time. Some birds utter a shrill cry during 

 the performance, others are entirely silent. All seemed to move their 

 wings so rapidly as to produce a humming sound, which varies in intensity 

 from a barely audible whisper to a deep drumming sound easily audible 

 a hundred yards away. 



42. Machetornis rixosa rixosa (Vieill.). — This tyrant bird is colored 

 in a way which is very suggestive of many species of Tyrannus; but its 

 habits are entirely different. It lives on the ground, and is most often 

 seen about the heads of the domestic animals with the cowbirds, and it 

 is due to this fact that they have been given the common name " Ovejera " 

 (shepherd) . 



43. Myiosympotes flaviventris (Orb. et Lafr.).^This little tyrant 

 is one of the most common of the family at La Plata, being found wherever 

 there are scattering bushes or where the weeds grow tall. There is little 

 in its habits to suggest a tyrant bird; rather it suggests a small Vireo, 

 though perhaps it is more energetic in its movements than those birds; 

 and it has a rather formal little song of six or seven notes which it delivers 

 in a jerky manner. 



■ 44. Serpophaga subcristata (Vieill.). — A small tyrant bird whose 

 appearance and habits suggest a Polioptila. It was quite common in the 

 bushes about the observatory, and also at Los Talas. While it was first 

 seen in July, it was most common from September on. 



45. Serpophaga nigricans (Vieill.). — Much less often seen than the 

 preceding, and only at Los Talas, where it was flitting restlessly along the 

 canals, snatching its food in the air. 



46. Cyanotis rubrigaster (Vieill.). The " Siete colores " (Seven 

 colors) is one of the most beautiful birds I have ever seen. While he is 

 most at home in the tall marsh grass, he is often found elsewhere during 



