For each plot the composition of the warbler population and the volume of the foliage above 20 feet are indicated in figure 10. Here "others" refers to other tree-nesting warblers which fed above 20 feet. It is quite clear that the total tree
nesting warbler population is very nearly proportional to the foliage volume. The abundance of the myrtle warbler is evidently quite constant. only increasing slowly as the volume of foliage increases. This is probably due to its fly catching
and ground feeding habits which help to make it less dependent upon the foliage.