NO. 7 i LOCKS OP NEOTROPICAL BIRDS — MOYNIIIAN 15 



As soon as any single bird or flock was counted, he resumed walking 

 around the clearing. As most periods of observation lasted for several 

 hours, the observer repeatedly retraced his steps and made counts in 

 the same places. Many individual birds and some flocks were undoubt- 

 edly counted several times during any single period of observation. 

 Individual birds and flocks that did not move about very much were 

 counted repeatedly in the same places. (It should be noted, however, 

 that the composition of mixed flocks usually changed, to a greater or 

 lesser extent, between successive counts.) Individual birds and flocks 

 that did move about appreciably (as most did) were often counted 

 several times in different places, although a definite attempt was made 

 not to count the same individuals or flocks twice within 15 minutes. 

 Most individual birds around the clearing were also counted repeatedly 

 on successive days. 



Thus the figures shown in table 1 under the headings "Number of 

 times individuals seen in mixed flocks" and "Number of times indi- 

 viduals seen not in mixed flocks" are certainly very much larger than 

 the real numbers of individual birds seen in mixed flocks and apart 

 from mixed flocks. 



It is difficult to estimate the actual numbers of individual birds of 

 different species in and around the clearing during the periods in 

 which these counts were made, as few of the birds were distinctively 

 marked or banded, and there were certainly some changes in the popu- 

 lations of some or all species between October and December. As a 

 very rough estimate, I would guess that there were at least 10 plain - 

 colored tanagers (quite possibly 16), 4 palm tanagers, 4 blue tanagers, 

 2 golden-masked tanagers, 5 green honeycreepers, 6 red-legged blue 

 honeycreepers, 4 crimson-backed tanagers, 2 summer tanagers, 2 

 fulvous-vented euphonias, 4 bananaquits, and 2 yellow warblers in 

 and around the clearing more or less regularly during all or most of 

 the period between October and December. Additional individuals of 

 all or most of these species turned up from time to time, but usually 

 did not stay long. 



(It will be noted that no finches are included in table 1. Most of the 

 finches in and around the clearing seldom or never joined the mixed 

 flocks of the blue and green tanager and honeycreeper alliance or 

 went very high in the trees. The only exceptions were variable seed- 

 eaters, some of which, especially males, did go high in the trees and 

 were frequently associated with mixed blue and green tanager and 

 honeycreeper flocks. They are not counted in table 1 simply because 

 they spent most of their time on the ground or in low grass in the 



