no. 7 



FLOCKS OF NEOTROPICAL BIRDS — MOYNIHAN 



17 



two or more tanagers of the same species were seen together in the 

 same small tree at the same time they were counted as one in these 

 columns. 



The total number of times each species was seen is also indicated 

 in table 2, in the third column. The percentage of times each species 



Table 2. — Data from observations in and aromid the clearing on Barro Colorado 

 Island between October 26 and December 20, 1959 



The number of times certain species of the blue and green tanager and honey- 

 creeper alliance were seen in mixed flocks and apart from mixed flocks, and the 

 average number of individuals of each of these species per mixed flock and per 

 nonmixed flock. 



No. of 

 times 

 species 

 seen in 

 mixed 

 flocks 



No. of 

 times 

 species 

 seen not 

 in mixed 

 flocks 



Percentage Average Average 



Total No. of times No. individ- No. individ- 



times species uals per ualsper 



species seen mixed nonmixed 



seen mixed flock flock 



Species 



Plain-colored 

 tanagers 



Palm tanagers . . 



Blue tanagers . . 



Golden-masked 

 tanagers 



Green honey- 

 creepers 



Red-legged blue 

 honeycreepers 



Blue dacnises . . 



Crimson-backed 

 tanagers 



Summer tanagers 



Fulvous-vented 

 euphonias 



Bananaquits 



Yellow warblers 



was seen in mixed flocks is shown in the fourth column. These per- 

 centage figures were calculated by using the figures in the first and 

 third columns. 



Finally, the average number of individuals of the different species 

 per mixed flock and per nonmixed flock is indicated in the last two 

 columns of table 2. For this purpose every solitary individual that 

 was seen by itself alone, without any other birds of the same or any 

 other species nearby, was considered to form a separate nonmixed 

 flock of its own. 



172 



126 



96 



25 

 50 



47 



26 



19 

 20 



13 



44 

 V] 



202 

 108 

 ITI 



36 



58 



22 

 32 



65 

 27 



I I 



68 

 75 



374 

 234 

 207 



61 



108 



69 



58 



84 



47 



24 



112 

 93 



46 



54 

 46 



41 

 46 



68 



45 



23 

 43 



54 

 39 

 18 



2.78 



MS 

 I.26 



1. 00 



1. 00 



1.79 



1.27 



2.II 

 LIS 



1.08 

 I.l8 



1. 00 



2.82 

 1.44 

 1.33 



1. 00 



1.09 



1.40 

 1.03 



1.86 

 1. 11 



1. 00 

 1. 21 

 1. 00 



