348 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1930 



stands. The lowest nests were about 100 feet above the base of the 

 tree, the highest about 20 feet below its top. The nearest nests to 

 our viewpoint at the laboratory level were distant about 80 feet. 

 This statement is of interest chiefly from the standpoint of the pho- 

 tographer. With an elaborate equipment, including lenses up to 23 

 inches in focal length, the distance, a background of leaves, the com- 

 paratively small size and dark colors of the birds, prevented me from 

 securing adequate photographs of them. 



The conditions under which the birds were watched were far more 

 satisfactory. My observation post was the open space beneath my 

 house situated 15 feet higher than the laboratory, and about 100 yards 

 from the tree in which the oropendolas nested. Seated in a camp 

 chair with a desk board across its arms, and using a 24-power binocu- 

 lar mounted on a tripod, the birds, wholly unaware of my presence, 

 seemed to be within reach of my hand. Every detail of their move- 

 ments, even to the motion of the tongue when calling, could be seen 

 clearly and with such ease that I could observe and record their 

 actions for hours at a sitting without fatigue. I did not acquire this 

 high-power glass until the second season. Its lack in 1925-26, when 

 an 8-power glass was used from the laboratory level, greatly detracted 

 from the value of that season's work. 



Diagrams were made showing the relative position of the nests. 

 Each one was numbered and its history, as far as possible, carefully 

 recorded. When last observed, the colony of 1926 contained 39 

 nests; that of 1927, 29 nests. In 1928, 16 nests were built, but for 

 various reasons, as recounted beyond, all were deserted apparently 

 before eggs were laid, and the colony was abandoned. 



It is a significant comment on our lack of knowledge of the 

 habits of troj)ical American birds that, although by size, voice, and 

 nests the oropendolas and caciques are among the best known birds 

 of that region, their life histories are as yet unwritten. One finds 

 short descriptions of their loud notes and the postures of the male 

 when calling, of the appearance and, in some few cases, structure 

 and contents of their nests. There are also several records of 

 parasitism by Cassidix oryzivora^ but all the statements made are 

 based on casual or brief observations and no definite, continuous 

 study of any member of the group has apparently been made. 



The oropendolas offer, however, an exceptionally interesting sub- 

 ject for the field student. If the nature of the nesting site prohibits 

 close examination of the nest in situ, it at least gives an admirable 

 view of the colony as a unit and hence of the group activities of 

 its members. The movements of the individual may also be closely 

 followed and the colonial habits of the species enable one to observe 

 a number of birds at the same time and under similar conditions. 



