382 ANNUAL EEPOET SMITHSONIAN INSTITUTION, 19 3 



Zarhynchus drives the too willing performer from his perch but be- 

 yond this no attention is paid to him. According to Jewell, as re- 

 ported by Stone/* Cacicus nests in the Canal Zone in March. One 

 might imagine, therefore, that the male or males that devote them- 

 selves so earnestly to the Zarhynchus colony might find more 

 appreciative listeners in the females of their own species. 



AntJiracothorax nkjricoTlis. — Nesting in the sand-box tree evi- 

 dently gives the black-throated hununer a sense of proprietorship 

 Avhich leads it to attack nearly every trespassing species including 

 Zarhynchus and its enemy Gassidix. The bird, therefore, plays some 

 part in the nest life of the oropendola while the regularity of its 

 return to the nest tree affords additional evidenc eof marked perio- 

 dicity and localization in tropical birds. 



On January 16, 1926, a black-throated humming bird was dis- 

 covered on the eastern side of the sand-box tree building its nest near 

 the tip of an absolutely bare limb at least 25 feet from the nearest leaf. 

 There was not a more expose site in the tree. From this point it 

 attacked birds trespassing within its territory with a dash and 

 courage which promptly put them to flight. Oropendolas were 

 frequently followed to their nesting quarters and sometimes driven 

 from the tree. So effective and persistent were the bird's assaults 

 it seemed not improbable that if they had been made before the 

 oropendolas had begun to build they might have prevented them 

 from settling in the tree. 



On only one occasion did the bird retreat before a trespassing 

 species, this was a white snake-hawk {Leucopfernis ghieshrechti) 

 which in one instance perched within a few feet of the hummer which 

 promptly took flight. On the other hand a bucco {Bucco subtectus) 

 was permitted to sit for some time near the hununer's nest without 

 molestation. The nest was apparently completed about January 20, 

 and the bird began to sit some time between January 21 and 25. It 

 was believed to contain young on February 9, and on the 11th the 

 parent was definitely seen to feed the young. On February 19 the 

 lulls of both young could be seen above the rim of the nest. On this 

 date observation ceased. 



In 1927 a humming bird of the same species built a nest on the 

 nearest available site to the one occupied in 1927, the limb on which 

 that nest was placed having meanwhile fallen. When discovered 

 on January 19 the bird appeared to be incubating. On the morning 

 of January 30 this nest and bird were missing. 



On January 11, 1928, a female violet-throated humming bird was 

 discovered building a nest at or very near the site occupied by this 

 species in 1927. She apparently began to sit about January 15. 



" 1918, Proc. Acad. Nat. Sci., Pbila., p. 280. 



